repo fix

* Add exemplars simple example, add go runtime and process collectors to simple example

Signed-off-by: Jéssica Lins <jessicaalins@gmail.com>

* Add middleware example

Signed-off-by: Jéssica Lins <jessicaalins@gmail.com>

* Lint

Signed-off-by: Jéssica Lins <jessicaalins@gmail.com>

Signed-off-by: Jéssica Lins <jessicaalins@gmail.com>

.circleci/config.yml

@@ -1,7 +1,7 @@
 version: 2.1
 orbs:
-  go: circleci/go@0.2.0
+  go: circleci/go@1.7.1
-  prometheus: prometheus/prometheus@0.15.0
+  prometheus: prometheus/prometheus@0.16.0
 jobs:
   test:
     parameters:
@@ -17,8 +17,7 @@ jobs:
         type: boolean
         default: true
     docker:
-      - image: circleci/golang:<< parameters.go_version >>
+      - image: cimg/go:<< parameters.go_version >>
-    working_directory: /go/src/github.com/prometheus/client_golang
     steps:
       - checkout
       - when:
@@ -47,24 +46,18 @@ workflows:
   client_golang:
     jobs:
       # Refer to README.md for the currently supported versions.
-      - test:
-          name: go-1-13
-          go_version: "1.13"
-          run_lint: true
-      - test:
-          name: go-1-14
-          go_version: "1.14"
-          run_lint: true
-      - test:
-          name: go-1-15
-          go_version: "1.15"
-          run_lint: true
-      - test:
-          name: go-1-16
-          go_version: "1.16"
-          run_lint: true
       - test:
           name: go-1-17
           go_version: "1.17"
           run_lint: true
+      - test:
+          name: go-1-18
+          go_version: "1.18"
+          run_lint: true
+      - test:
+          name: go-1-19
+          go_version: "1.19"
+          run_lint: true
+          # Style and unused/missing packages are only checked against
+          # the latest supported Go version.
           run_style_and_unused: true

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "monthly"

.github/settings.yml

@@ -0,0 +1,34 @@
+---
+branches:
+  - name: main
+    protection:
+      # Required. Require at least one approving review on a pull request, before merging. Set to null to disable.
+      required_pull_request_reviews:
+        # The number of approvals required. (1-6)
+        required_approving_review_count: 1
+        # Dismiss approved reviews automatically when a new commit is pushed.
+        dismiss_stale_reviews: false
+        # Blocks merge until code owners have reviewed.
+        require_code_owner_reviews: false
+        # Specify which users and teams can dismiss pull request reviews. Pass an empty dismissal_restrictions object to disable. User and team dismissal_restrictions are only available for organization-owned repositories. Omit this parameter for personal repositories.
+        dismissal_restrictions:
+          users: []
+          teams: []
+      # Required. Require status checks to pass before merging. Set to null to disable
+      required_status_checks:
+        # Required. Require branches to be up to date before merging.
+        strict: false
+        # Required. The list of status checks to require in order to merge into this branch
+        contexts:
+          - DCO
+          - "ci/circleci: go-1-17"
+          - "ci/circleci: go-1-18"
+      # Required. Enforce all configured restrictions for administrators. Set to true to enforce required status checks for repository administrators. Set to null to disable.
+      enforce_admins: false
+      # Prevent merge commits from being pushed to matching branches
+      required_linear_history: false
+      # Required. Restrict who can push to this branch. Team and user restrictions are only available for organization-owned repositories. Set to null to disable.
+      restrictions:
+        apps: []
+        users: []
+        teams: []

.github/stale.yml

@@ -0,0 +1,88 @@
+# Configuration for probot-stale - https://github.com/probot/stale
+
+# Number of days of inactivity before an Issue or Pull Request becomes stale
+# daysUntilStale: 30
+
+# Number of days of inactivity before an Issue or Pull Request with the stale label is closed.
+# Set to false to disable. If disabled, issues still need to be closed manually, but will remain marked as stale.
+# daysUntilClose: 7
+
+# NOTICE: Check below for the individual settings for each type of event.
+
+# Only issues or pull requests with all of these labels are check if stale. Defaults to `[]` (disabled)
+onlyLabels: []
+
+# Issues or Pull Requests with these labels will never be considered stale. Set to `[]` to disable
+exemptLabels:
+  - pinned
+  - security
+  - keep-open
+  - wip
+  - "[Status] Maybe Later"
+
+# Set to true to ignore issues in a project (defaults to false)
+exemptProjects: true # default: false
+
+# Set to true to ignore issues in a milestone (defaults to false)
+exemptMilestones: true # default: false
+
+# Set to true to ignore issues with an assignee (defaults to false)
+exemptAssignees: false
+
+# Label to use when marking as stale
+staleLabel: stale
+
+# Comment to post when marking as stale. Set to `false` to disable
+# markComment: >
+#  This issue has been automatically marked as stale because it has not had
+#  recent activity. It will be closed if no further activity occurs. Thank you
+#  for your contributions.
+
+# Comment to post when removing the stale label.
+# unmarkComment: >
+#   Your comment here.
+
+# Comment to post when closing a stale Issue or Pull Request.
+# closeComment: >
+#   Your comment here.
+
+# Limit the number of actions per hour, from 1-30. Default is 30
+limitPerRun: 30
+
+# Limit to only `issues` or `pulls`
+# only: issues
+
+# Optionally, specify configuration settings that are specific to just 'issues' or 'pulls':
+# pulls:
+#   daysUntilStale: 30
+#   markComment: >
+#     This pull request has been automatically marked as stale because it has not had
+#     recent activity. It will be closed if no further activity occurs. Thank you
+#     for your contributions.
+
+# issues:
+#   exemptLabels:
+#     - confirmed
+
+pull:
+  daysUntilClose: 14
+  daysUntilStale: 60
+  markComment: >
+    Hello 👋 Looks like there was no activity on this amazing PR for the last 60 days.
+    **Do you mind updating us on the status?** Is there anything we can help with? If you plan to still work on it, just comment on this PR or push a commit. Thanks! 🤗
+    
+    If there will be no activity in the next 2 weeks, this issue will be closed (we can always reopen a PR if you get back to this!).
+  # unmarkComment: No need for unmark comment.
+  closeComment: >
+    Closing for now as promised, let us know if you need this to be reopened! 🤗
+issues:
+  daysUntilClose: 90
+  daysUntilStale: 180
+  markComment: >
+    Hello 👋 Looks like there was no activity on this issue for the last 3 months.
+    **Do you mind updating us on the status?** Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
+    
+    If there will be no activity in the next 4 weeks, this issue will be closed (we can always reopen an issue if we need!).
+  # unmarkComment: No need for unmark comment.
+  closeComment: >
+    Closing for now as promised, let us know if you need this to be reopened! 🤗

.github/workflows/codeql-analysis.yml

@@ -0,0 +1,70 @@
+# For most projects, this workflow file will not need changing; you simply need
+# to commit it to your repository.
+#
+# You may wish to alter this file to override the set of languages analyzed,
+# or to provide custom queries or build logic.
+#
+# ******** NOTE ********
+# We have attempted to detect the languages in your repository. Please check
+# the `language` matrix defined below to confirm you have the correct set of
+# supported CodeQL languages.
+#
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ main ]
+  schedule:
+    - cron: '31 21 * * 6'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'go' ]
+        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python', 'ruby' ]
+        # Learn more about CodeQL language support at https://git.io/codeql-language-support
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      with:
+        languages: ${{ matrix.language }}
+        # If you wish to specify custom queries, you can do so here or in a config file.
+        # By default, queries listed here will override any specified in a config file.
+        # Prefix the list here with "+" to use these queries and those in the config file.
+        # queries: ./path/to/local/query, your-org/your-repo/queries@main
+
+    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below)
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v1
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1

.github/workflows/golangci-lint.yml

@@ -9,13 +9,6 @@ on:
       - ".github/workflows/golangci-lint.yml"
       - ".golangci.yml"
   pull_request:
-    paths:
-      - "go.sum"
-      - "go.mod"
-      - "**.go"
-      - "scripts/errcheck_excludes.txt"
-      - ".github/workflows/golangci-lint.yml"
-      - ".golangci.yml"
 
 jobs:
   golangci:
@@ -23,9 +16,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
-
+      - name: install Go
-      - name: Lint
+        uses: actions/setup-go@v2
-        uses: golangci/golangci-lint-action@v2
         with:
-          version: v1.42.0
+          go-version: 1.18.x
+      - name: Install snmp_exporter/generator dependencies
+        run: sudo apt-get update && sudo apt-get -y install libsnmp-dev
+        if: github.repository == 'prometheus/snmp_exporter'
+      - name: Lint
+        uses: golangci/golangci-lint-action@v3.2.0
+        with:
+          version: v1.45.2

.gitignore

@@ -12,7 +12,7 @@ examples/gocollector/gocollector
 vendor/
 
 # The remainder of this file is taken from
-# https://github.com/github/gitignore/blob/master/Go.gitignore
+# https://github.com/github/gitignore/blob/main/Go.gitignore
 
 # Binaries for programs and plugins
 *.exe

.go-version

@@ -0,0 +1 @@
+1.18

.golangci.yml

@@ -1,5 +1,47 @@
-# Run only staticcheck for now. Additional linters will be enabled one-by-one.
+---
+
+run:
+  deadline: 5m
+
+output:
+  sort-results: true
+
 linters:
   enable:
-  - staticcheck
+    - deadcode
-  disable-all: true
+    - depguard
+    - durationcheck
+    - errorlint
+    - exportloopref
+    - gofmt
+    - gofumpt
+    - goimports
+    - gosimple
+    - ineffassign
+    - misspell
+    - nolintlint
+    - predeclared
+    - revive
+    - staticcheck
+    - structcheck
+    - unconvert
+    - unused
+    - varcheck
+    - wastedassign
+
+issues:
+  max-same-issues: 0
+  exclude-rules:
+    - path: _test.go
+      linters:
+        - errcheck
+        - govet
+        - structcheck
+
+linters-settings:
+  errcheck:
+    exclude: scripts/errcheck_excludes.txt
+  goimports:
+    local-prefixes: git.internal/re/client_golang
+  gofumpt:
+    extra-rules: true

CHANGELOG.md

@@ -1,10 +1,37 @@
 ## Unreleased
 
-* [CHANGE] Minimum required Go version is now 1.16.
+## 1.14.0 / 2022-11-08
 
-## 1.12.2 / 2022-01-29
+* [FEATURE] Add Support for Native Histograms. #1150
+* [CHANGE] Extend `prometheus.Registry` to implement `prometheus.Collector` interface. #1103
 
-* [CHANGE] Added `collectors.WithGoCollections` that allows to choose what collection of Go runtime metrics user wants: Equivalent of [`MemStats` structure](https://pkg.go.dev/runtime#MemStats) configured using `GoRuntimeMemStatsCollection`, new based on dedicated [runtime/metrics](https://pkg.go.dev/runtime/metrics) metrics represented by `GoRuntimeMetricsCollection` option, or both by specifying `GoRuntimeMemStatsCollection | GoRuntimeMetricsCollection` flag.
+## 1.13.1 / 2022-11-01
+
+* [BUGFIX] Fix race condition with Exemplar in Counter. #1146
+* [BUGFIX] Fix `CumulativeCount` value of `+Inf` bucket created from exemplar. #1148
+* [BUGFIX] Fix double-counting bug in `promhttp.InstrumentRoundTripperCounter`. #1118
+
+## 1.13.0 / 2022-08-05
+
+* [CHANGE] Minimum required Go version is now 1.17 (we also test client_golang against new 1.19 version).
+* [ENHANCEMENT] Added `prometheus.TransactionalGatherer` interface for `promhttp.Handler` use which allows using low allocation update techniques for custom collectors. #989
+* [ENHANCEMENT] Added exemplar support to `prometheus.NewConstHistogram`. See [`ExampleNewConstHistogram_WithExemplar`](prometheus/examples_test.go#L602) example on how to use it. #986
+* [ENHANCEMENT] `prometheus/push.Pusher` has now context aware methods that pass context to HTTP request. #1028
+* [ENHANCEMENT] `prometheus/push.Pusher` has now `Error` method that retrieve last error. #1075
+* [ENHANCEMENT] `testutil.GatherAndCompare` provides now readable diff on failed comparisons. #998
+* [ENHANCEMENT] Query API now supports timeouts. #1014
+* [ENHANCEMENT] New `MetricVec` method `DeletePartialMatch(labels Labels)` for deleting all metrics that match provided labels. #1013
+* [ENHANCEMENT] `api.Config` now accepts passing custom `*http.Client`. #1025
+* [BUGFIX] Raise exemplar labels limit from 64 to 128 bytes as specified in OpenMetrics spec. #1091
+* [BUGFIX] Allow adding exemplar to +Inf bucket to const histograms. #1094
+* [ENHANCEMENT] Most `promhttp.Instrument*` middlewares now supports adding exemplars to metrics. This allows hooking those to your tracing middleware that retrieves trace ID and put it in exemplar if present. #1055
+* [ENHANCEMENT] Added `testutil.ScrapeAndCompare` method. #1043
+* [BUGFIX] Fixed `GopherJS` build support. #897
+* [ENHANCEMENT] :warning: Added way to specify what `runtime/metrics`  `collectors.NewGoCollector` should use. See [`ExampleGoCollector_WithAdvancedGoMetrics`](prometheus/collectors/go_collector_latest_test.go#L263). #1102
+
+## 1.12.2 / 2022-05-13
+
+* [CHANGE] Added `collectors.WithGoCollections` that allows to choose what collection of Go runtime metrics user wants: Equivalent of [`MemStats` structure](https://pkg.go.dev/runtime#MemStats) configured using `GoRuntimeMemStatsCollection`, new based on dedicated [runtime/metrics](https://pkg.go.dev/runtime/metrics) metrics represented by `GoRuntimeMetricsCollection` option, or both by specifying `GoRuntimeMemStatsCollection | GoRuntimeMetricsCollection` flag. #1031
 * [CHANGE] :warning: Change in `collectors.NewGoCollector` metrics: Reverting addition of new ~80 runtime metrics by default. You can enable this back with `GoRuntimeMetricsCollection` option or `GoRuntimeMemStatsCollection | GoRuntimeMetricsCollection` for smooth transition.
 * [BUGFIX] Fixed the bug that causes generated histogram metric names to end with `_total`. ⚠️ This changes 3 metric names in the new Go collector that was reverted from default in this release.
   * `go_gc_heap_allocs_by_size_bytes_total` -> `go_gc_heap_allocs_by_size_bytes`,

CODE_OF_CONDUCT.md

@@ -1,3 +1,3 @@
-## Prometheus Community Code of Conduct
+# Prometheus Community Code of Conduct
 
-Prometheus follows the [CNCF Code of Conduct](https://github.com/cncf/foundation/blob/master/code-of-conduct.md).
+Prometheus follows the [CNCF Code of Conduct](https://github.com/cncf/foundation/blob/main/code-of-conduct.md).

Dockerfile

@@ -1,26 +1,34 @@
 # This Dockerfile builds an image for a client_golang example.
 #
 # Use as (from the root for the client_golang repository):
-#    docker build -f examples/$name/Dockerfile -t prometheus/golang-example-$name .
+#    docker build -f Dockerfile -t prometheus/golang-example .
+
+# Run as
+#    docker run -P prometheus/golang-example /random
+# or
+#    docker run -P prometheus/golang-example /simple
+
+# Test as
+#    curl $ip:$port/metrics
 
 # Builder image, where we build the example.
 FROM golang:1 AS builder
-WORKDIR /go/src/github.com/prometheus/client_golang
+WORKDIR /go/src/git.internal/re/client_golang
 COPY . .
-WORKDIR /go/src/github.com/prometheus/client_golang/prometheus
+WORKDIR /go/src/git.internal/re/client_golang/prometheus
 RUN go get -d
-WORKDIR /go/src/github.com/prometheus/client_golang/examples/random
+WORKDIR /go/src/git.internal/re/client_golang/examples/random
 RUN CGO_ENABLED=0 GOOS=linux go build -a -tags netgo -ldflags '-w'
-WORKDIR /go/src/github.com/prometheus/client_golang/examples/simple
+WORKDIR /go/src/git.internal/re/client_golang/examples/simple
 RUN CGO_ENABLED=0 GOOS=linux go build -a -tags netgo -ldflags '-w'
-WORKDIR /go/src/github.com/prometheus/client_golang/examples/gocollector
+WORKDIR /go/src/git.internal/re/client_golang/examples/gocollector
 RUN CGO_ENABLED=0 GOOS=linux go build -a -tags netgo -ldflags '-w'
 
 # Final image.
 FROM quay.io/prometheus/busybox:latest
 LABEL maintainer="The Prometheus Authors <prometheus-developers@googlegroups.com>"
-COPY --from=builder /go/src/github.com/prometheus/client_golang/examples/random \
+COPY --from=builder /go/src/git.internal/re/client_golang/examples/random \
-    /go/src/github.com/prometheus/client_golang/examples/simple \
+    /go/src/git.internal/re/client_golang/examples/simple \
-    /go/src/github.com/prometheus/client_golang/examples/gocollector ./
+    /go/src/git.internal/re/client_golang/examples/gocollector ./
 EXPOSE 8080
 CMD ["echo", "Please run an example. Either /random, /simple or /gocollector"]

Makefile

@@ -18,3 +18,11 @@ test: deps common-test
 
 .PHONY: test-short
 test-short: deps common-test-short
+
+.PHONY: generate-go-collector-test-files
+VERSIONS := 1.17 1.18 1.19
+generate-go-collector-test-files:
+	for GO_VERSION in $(VERSIONS); do \
+    	docker run --rm -v $(PWD):/workspace -w /workspace golang:$$GO_VERSION go run prometheus/gen_go_collector_metrics_set.go; \
+		mv -f go_collector_metrics* prometheus; \
+    done

Makefile.common

@@ -36,29 +36,6 @@ GO_VERSION        ?= $(shell $(GO) version)
 GO_VERSION_NUMBER ?= $(word 3, $(GO_VERSION))
 PRE_GO_111        ?= $(shell echo $(GO_VERSION_NUMBER) | grep -E 'go1\.(10|[0-9])\.')
 
-GOVENDOR :=
-GO111MODULE :=
-ifeq (, $(PRE_GO_111))
-	ifneq (,$(wildcard go.mod))
-		# Enforce Go modules support just in case the directory is inside GOPATH (and for Travis CI).
-		GO111MODULE := on
-
-		ifneq (,$(wildcard vendor))
-			# Always use the local vendor/ directory to satisfy the dependencies.
-			GOOPTS := $(GOOPTS) -mod=vendor
-		endif
-	endif
-else
-	ifneq (,$(wildcard go.mod))
-		ifneq (,$(wildcard vendor))
-$(warning This repository requires Go >= 1.11 because of Go modules)
-$(warning Some recipes may not work as expected as the current Go runtime is '$(GO_VERSION_NUMBER)')
-		endif
-	else
-		# This repository isn't using Go modules (yet).
-		GOVENDOR := $(FIRST_GOPATH)/bin/govendor
-	endif
-endif
 PROMU        := $(FIRST_GOPATH)/bin/promu
 pkgs          = ./...
 
@@ -83,7 +60,7 @@ PROMU_URL     := https://github.com/prometheus/promu/releases/download/v$(PROMU_
 
 GOLANGCI_LINT :=
 GOLANGCI_LINT_OPTS ?=
-GOLANGCI_LINT_VERSION ?= v1.42.0
+GOLANGCI_LINT_VERSION ?= v1.45.2
 # golangci-lint only supports linux, darwin and windows platforms on i386/amd64.
 # windows isn't included here because of the path separator being different.
 ifeq ($(GOHOSTOS),$(filter $(GOHOSTOS),linux darwin))
@@ -150,11 +127,7 @@ common-check_license:
 .PHONY: common-deps
 common-deps:
 	@echo ">> getting dependencies"
-ifdef GO111MODULE
+	$(GO) mod download
-	GO111MODULE=$(GO111MODULE) $(GO) mod download
-else
-	$(GO) get $(GOOPTS) -t ./...
-endif
 
 .PHONY: update-go-deps
 update-go-deps:
@@ -162,20 +135,17 @@ update-go-deps:
 	@for m in $$($(GO) list -mod=readonly -m -f '{{ if and (not .Indirect) (not .Main)}}{{.Path}}{{end}}' all); do \
 		$(GO) get -d $$m; \
 	done
-	GO111MODULE=$(GO111MODULE) $(GO) mod tidy
+	$(GO) mod tidy
-ifneq (,$(wildcard vendor))
-	GO111MODULE=$(GO111MODULE) $(GO) mod vendor
-endif
 
 .PHONY: common-test-short
 common-test-short: $(GOTEST_DIR)
 	@echo ">> running short tests"
-	GO111MODULE=$(GO111MODULE) $(GOTEST) -short $(GOOPTS) $(pkgs)
+	$(GOTEST) -short $(GOOPTS) $(pkgs)
 
 .PHONY: common-test
 common-test: $(GOTEST_DIR)
 	@echo ">> running all tests"
-	GO111MODULE=$(GO111MODULE) $(GOTEST) $(test-flags) $(GOOPTS) $(pkgs)
+	$(GOTEST) $(test-flags) $(GOOPTS) $(pkgs)
 
 $(GOTEST_DIR):
 	@mkdir -p $@
@@ -183,25 +153,21 @@ $(GOTEST_DIR):
 .PHONY: common-format
 common-format:
 	@echo ">> formatting code"
-	GO111MODULE=$(GO111MODULE) $(GO) fmt $(pkgs)
+	$(GO) fmt $(pkgs)
 
 .PHONY: common-vet
 common-vet:
 	@echo ">> vetting code"
-	GO111MODULE=$(GO111MODULE) $(GO) vet $(GOOPTS) $(pkgs)
+	$(GO) vet $(GOOPTS) $(pkgs)
 
 .PHONY: common-lint
 common-lint: $(GOLANGCI_LINT)
 ifdef GOLANGCI_LINT
 	@echo ">> running golangci-lint"
-ifdef GO111MODULE
 # 'go list' needs to be executed before staticcheck to prepopulate the modules cache.
 # Otherwise staticcheck might fail randomly for some reason not yet explained.
-	GO111MODULE=$(GO111MODULE) $(GO) list -e -compiled -test=true -export=false -deps=true -find=false -tags= -- ./... > /dev/null
+	$(GO) list -e -compiled -test=true -export=false -deps=true -find=false -tags= -- ./... > /dev/null
-	GO111MODULE=$(GO111MODULE) $(GOLANGCI_LINT) run $(GOLANGCI_LINT_OPTS) $(pkgs)
+	$(GOLANGCI_LINT) run $(GOLANGCI_LINT_OPTS) $(pkgs)
-else
-	$(GOLANGCI_LINT) run $(pkgs)
-endif
 endif
 
 .PHONY: common-yamllint
@@ -218,28 +184,15 @@ endif
 common-staticcheck: lint
 
 .PHONY: common-unused
-common-unused: $(GOVENDOR)
+common-unused:
-ifdef GOVENDOR
-	@echo ">> running check for unused packages"
-	@$(GOVENDOR) list +unused | grep . && exit 1 || echo 'No unused packages'
-else
-ifdef GO111MODULE
 	@echo ">> running check for unused/missing packages in go.mod"
-	GO111MODULE=$(GO111MODULE) $(GO) mod tidy
+	$(GO) mod tidy
-ifeq (,$(wildcard vendor))
 	@git diff --exit-code -- go.sum go.mod
-else
-	@echo ">> running check for unused packages in vendor/"
-	GO111MODULE=$(GO111MODULE) $(GO) mod vendor
-	@git diff --exit-code -- go.sum go.mod vendor/
-endif
-endif
-endif
 
 .PHONY: common-build
 common-build: promu
 	@echo ">> building binaries"
-	GO111MODULE=$(GO111MODULE) $(PROMU) build --prefix $(PREFIX) $(PROMU_BINARIES)
+	$(PROMU) build --prefix $(PREFIX) $(PROMU_BINARIES)
 
 .PHONY: common-tarball
 common-tarball: promu
@@ -295,12 +248,6 @@ $(GOLANGCI_LINT):
 		| sh -s -- -b $(FIRST_GOPATH)/bin $(GOLANGCI_LINT_VERSION)
 endif
 
-ifdef GOVENDOR
-.PHONY: $(GOVENDOR)
-$(GOVENDOR):
-	GOOS= GOARCH= $(GO) get -u github.com/kardianos/govendor
-endif
-
 .PHONY: precheck
 precheck::
 

README.md

@@ -1,15 +1,16 @@
 # Prometheus Go client library
 
-[![CircleCI](https://circleci.com/gh/prometheus/client_golang/tree/master.svg?style=svg)](https://circleci.com/gh/prometheus/client_golang/tree/master)
+[![CircleCI](https://circleci.com/gh/prometheus/client_golang/tree/main.svg?style=svg)](https://circleci.com/gh/prometheus/client_golang/tree/main)
-[![Go Report Card](https://goreportcard.com/badge/github.com/prometheus/client_golang)](https://goreportcard.com/report/github.com/prometheus/client_golang)
+[![Go Report Card](https://goreportcard.com/badge/git.internal/re/client_golang)](https://goreportcard.com/report/git.internal/re/client_golang)
-[![Go Reference](https://pkg.go.dev/badge/github.com/prometheus/client_golang.svg)](https://pkg.go.dev/github.com/prometheus/client_golang)
+[![Go Reference](https://pkg.go.dev/badge/git.internal/re/client_golang.svg)](https://pkg.go.dev/git.internal/re/client_golang)
+[![Slack](https://img.shields.io/badge/join%20slack-%23prometheus--client_golang-brightgreen.svg)](https://slack.cncf.io/)
 
 This is the [Go](http://golang.org) client library for
 [Prometheus](http://prometheus.io). It has two separate parts, one for
 instrumenting application code, and one for creating clients that talk to the
 Prometheus HTTP API.
 
-__This library requires Go1.13 or later.__
+__This library requires Go1.17 or later.__
 
 ## Important note about releases and stability
 
@@ -22,33 +23,33 @@ CHANGELOG.md.
 
 Features that require breaking changes in the stable parts of the repository
 are being batched up and tracked in the [v2
-milestone](https://github.com/prometheus/client_golang/milestone/2). The v2
+milestone](https://git.internal/re/client_golang/milestone/2). The v2
 development happens in a [separate
-branch](https://github.com/prometheus/client_golang/tree/dev-v2) for the time
+branch](https://git.internal/re/client_golang/tree/dev-v2) for the time
 being. v2 releases off that branch will happen once sufficient stability is
 reached. In view of the widespread use of this repository, v1 and v2 will
 coexist for a while to enable a convenient transition.
 
 ## Instrumenting applications
 
-[![code-coverage](http://gocover.io/_badge/github.com/prometheus/client_golang/prometheus)](http://gocover.io/github.com/prometheus/client_golang/prometheus) [![Go Reference](https://pkg.go.dev/badge/github.com/prometheus/client_golang/prometheus.svg)](https://pkg.go.dev/github.com/prometheus/client_golang/prometheus)
+[![code-coverage](http://gocover.io/_badge/git.internal/re/client_golang/prometheus)](http://gocover.io/git.internal/re/client_golang/prometheus) [![Go Reference](https://pkg.go.dev/badge/git.internal/re/client_golang/prometheus.svg)](https://pkg.go.dev/git.internal/re/client_golang/prometheus)
 
 The
-[`prometheus` directory](https://github.com/prometheus/client_golang/tree/master/prometheus)
+[`prometheus` directory](https://git.internal/re/client_golang/tree/main/prometheus)
 contains the instrumentation library. See the
 [guide](https://prometheus.io/docs/guides/go-application/) on the Prometheus
 website to learn more about instrumenting applications.
 
 The
-[`examples` directory](https://github.com/prometheus/client_golang/tree/master/examples)
+[`examples` directory](https://git.internal/re/client_golang/tree/main/examples)
 contains simple examples of instrumented code.
 
 ## Client for the Prometheus HTTP API
 
-[![code-coverage](http://gocover.io/_badge/github.com/prometheus/client_golang/api/prometheus/v1)](http://gocover.io/github.com/prometheus/client_golang/api/prometheus/v1) [![Go Reference](https://pkg.go.dev/badge/github.com/prometheus/client_golang/api.svg)](https://pkg.go.dev/github.com/prometheus/client_golang/api)
+[![code-coverage](http://gocover.io/_badge/git.internal/re/client_golang/api/prometheus/v1)](http://gocover.io/git.internal/re/client_golang/api/prometheus/v1) [![Go Reference](https://pkg.go.dev/badge/git.internal/re/client_golang/api.svg)](https://pkg.go.dev/git.internal/re/client_golang/api)
 
 The
-[`api/prometheus` directory](https://github.com/prometheus/client_golang/tree/master/api/prometheus)
+[`api/prometheus` directory](https://git.internal/re/client_golang/tree/main/api/prometheus)
 contains the client for the
 [Prometheus HTTP API](http://prometheus.io/docs/querying/api/). It allows you
 to write Go applications that query time series data from a Prometheus
@@ -57,12 +58,35 @@ server. It is still in alpha stage.
 ## Where is `model`, `extraction`, and `text`?
 
 The `model` packages has been moved to
-[`prometheus/common/model`](https://github.com/prometheus/common/tree/master/model).
+[`prometheus/common/model`](https://github.com/prometheus/common/tree/main/model).
 
 The `extraction` and `text` packages are now contained in
-[`prometheus/common/expfmt`](https://github.com/prometheus/common/tree/master/expfmt).
+[`prometheus/common/expfmt`](https://github.com/prometheus/common/tree/main/expfmt).
 
 ## Contributing and community
 
 See the [contributing guidelines](CONTRIBUTING.md) and the
 [Community section](http://prometheus.io/community/) of the homepage.
+
+`clint_golang` community is also present on the CNCF Slack `#prometheus-client_golang`.
+
+### For Maintainers: Release Process
+
+To cut a minor version:
+
+1. Create a new branch `release-<major>.<minor>` on top of the `main` commit you want to cut the version from and push it.
+2. Create a new branch on top of the release branch, e.g. `<yourname>/cut-<major>.<minor>.<patch>`,
+3. Change the `VERSION` file.
+4. Update `CHANGELOG` (only user-impacting changes to mention).
+5. Create PR, and get it reviewed.
+6. Once merged, create a release with the `release-<major>.<minor>` tag on GitHub with the `<version> / <date>` title.
+7. Announce on the prometheus-announce mailing list, slack and Twitter.
+8. Merge the release branch back to the `main` using the "merge without squashing" approach (!).
+
+> NOTE: In case of merge conflicts, you can checkout the release branch in a new branch, e.g. <yourname>/resolve-conflicts`, fix the merge problems there, and then do a PR into main from the new branch. In that way, you still get all the commits in the release branch back into `main`, but leave the release branch alone.
+
+To cut the patch version:
+
+1. Create a branch on top of the release branch you want to use.
+2. Cherry-pick the fixes from the `main` branch (or add new commits) to fix critical bugs for that patch release.
+3. Follow steps 3-8 as above.

SECURITY.md

@@ -3,4 +3,4 @@
 The Prometheus security policy, including how to report vulnerabilities, can be
 found here:
 
-https://prometheus.io/docs/operating/security/
+<https://prometheus.io/docs/operating/security/>

VERSION

@@ -1 +1 @@
-1.12.2
+1.14.0

api/client.go

@@ -17,6 +17,7 @@ package api
 import (
 	"bytes"
 	"context"
+	"errors"
 	"net"
 	"net/http"
 	"net/url"
@@ -40,6 +41,10 @@ type Config struct {
 	// The address of the Prometheus to connect to.
 	Address string
 
+	// Client is used by the Client to drive HTTP requests. If not provided,
+	// a new one based on the provided RoundTripper (or DefaultRoundTripper) will be used.
+	Client *http.Client
+
 	// RoundTripper is used by the Client to drive HTTP requests. If not
 	// provided, DefaultRoundTripper will be used.
 	RoundTripper http.RoundTripper
@@ -52,6 +57,22 @@ func (cfg *Config) roundTripper() http.RoundTripper {
 	return cfg.RoundTripper
 }
 
+func (cfg *Config) client() http.Client {
+	if cfg.Client == nil {
+		return http.Client{
+			Transport: cfg.roundTripper(),
+		}
+	}
+	return *cfg.Client
+}
+
+func (cfg *Config) validate() error {
+	if cfg.Client != nil && cfg.RoundTripper != nil {
+		return errors.New("api.Config.RoundTripper and api.Config.Client are mutually exclusive")
+	}
+	return nil
+}
+
 // Client is the interface for an API client.
 type Client interface {
 	URL(ep string, args map[string]string) *url.URL
@@ -68,9 +89,13 @@ func NewClient(cfg Config) (Client, error) {
 	}
 	u.Path = strings.TrimRight(u.Path, "/")
 
+	if err := cfg.validate(); err != nil {
+		return nil, err
+	}
+
 	return &httpClient{
 		endpoint: u,
-		client:   http.Client{Transport: cfg.roundTripper()},
+		client:   cfg.client(),
 	}, nil
 }
 
@@ -84,7 +109,7 @@ func (c *httpClient) URL(ep string, args map[string]string) *url.URL {
 
 	for arg, val := range args {
 		arg = ":" + arg
-		p = strings.Replace(p, arg, val, -1)
+		p = strings.ReplaceAll(p, arg, val)
 	}
 
 	u := *c.endpoint

api/client_test.go

@@ -134,7 +134,6 @@ func BenchmarkClient(b *testing.B) {
 
 	for _, sizeKB := range []int{4, 50, 1000, 2000} {
 		b.Run(fmt.Sprintf("%dKB", sizeKB), func(b *testing.B) {
-
 			testServer := httptest.NewServer(serveSpaces{sizeKB})
 			defer testServer.Close()
 

api/prometheus/v1/api.go

@@ -31,7 +31,7 @@ import (
 
 	"github.com/prometheus/common/model"
 
-	"github.com/prometheus/client_golang/api"
+	"git.internal/re/client_golang/api"
 )
 
 func init() {
@@ -109,7 +109,6 @@ func marshalPointJSON(ptr unsafe.Pointer, stream *json.Stream) {
 
 	stream.WriteRaw(`"`)
 	stream.WriteArrayEnd()
-
 }
 
 func marshalPointJSONIsEmpty(ptr unsafe.Pointer) bool {
@@ -230,25 +229,25 @@ type API interface {
 	// Config returns the current Prometheus configuration.
 	Config(ctx context.Context) (ConfigResult, error)
 	// DeleteSeries deletes data for a selection of series in a time range.
-	DeleteSeries(ctx context.Context, matches []string, startTime time.Time, endTime time.Time) error
+	DeleteSeries(ctx context.Context, matches []string, startTime, endTime time.Time) error
 	// Flags returns the flag values that Prometheus was launched with.
 	Flags(ctx context.Context) (FlagsResult, error)
 	// LabelNames returns the unique label names present in the block in sorted order by given time range and matchers.
-	LabelNames(ctx context.Context, matches []string, startTime time.Time, endTime time.Time) ([]string, Warnings, error)
+	LabelNames(ctx context.Context, matches []string, startTime, endTime time.Time) ([]string, Warnings, error)
 	// LabelValues performs a query for the values of the given label, time range and matchers.
-	LabelValues(ctx context.Context, label string, matches []string, startTime time.Time, endTime time.Time) (model.LabelValues, Warnings, error)
+	LabelValues(ctx context.Context, label string, matches []string, startTime, endTime time.Time) (model.LabelValues, Warnings, error)
 	// Query performs a query for the given time.
-	Query(ctx context.Context, query string, ts time.Time) (model.Value, Warnings, error)
+	Query(ctx context.Context, query string, ts time.Time, opts ...Option) (model.Value, Warnings, error)
 	// QueryRange performs a query for the given range.
-	QueryRange(ctx context.Context, query string, r Range) (model.Value, Warnings, error)
+	QueryRange(ctx context.Context, query string, r Range, opts ...Option) (model.Value, Warnings, error)
 	// QueryExemplars performs a query for exemplars by the given query and time range.
-	QueryExemplars(ctx context.Context, query string, startTime time.Time, endTime time.Time) ([]ExemplarQueryResult, error)
+	QueryExemplars(ctx context.Context, query string, startTime, endTime time.Time) ([]ExemplarQueryResult, error)
 	// Buildinfo returns various build information properties about the Prometheus server
 	Buildinfo(ctx context.Context) (BuildinfoResult, error)
 	// Runtimeinfo returns the various runtime information properties about the Prometheus server.
 	Runtimeinfo(ctx context.Context) (RuntimeinfoResult, error)
 	// Series finds series by label matchers.
-	Series(ctx context.Context, matches []string, startTime time.Time, endTime time.Time) ([]model.LabelSet, Warnings, error)
+	Series(ctx context.Context, matches []string, startTime, endTime time.Time) ([]model.LabelSet, Warnings, error)
 	// Snapshot creates a snapshot of all current data into snapshots/<datetime>-<rand>
 	// under the TSDB's data directory and returns the directory as response.
 	Snapshot(ctx context.Context, skipHead bool) (SnapshotResult, error)
@@ -257,9 +256,9 @@ type API interface {
 	// Targets returns an overview of the current state of the Prometheus target discovery.
 	Targets(ctx context.Context) (TargetsResult, error)
 	// TargetsMetadata returns metadata about metrics currently scraped by the target.
-	TargetsMetadata(ctx context.Context, matchTarget string, metric string, limit string) ([]MetricMetadata, error)
+	TargetsMetadata(ctx context.Context, matchTarget, metric, limit string) ([]MetricMetadata, error)
 	// Metadata returns metadata about metrics currently scraped by the metric name.
-	Metadata(ctx context.Context, metric string, limit string) (map[string][]Metadata, error)
+	Metadata(ctx context.Context, metric, limit string) (map[string][]Metadata, error)
 	// TSDB returns the cardinality statistics.
 	TSDB(ctx context.Context) (TSDBResult, error)
 	// WalReplay returns the current replay status of the wal.
@@ -336,14 +335,15 @@ type RuleGroup struct {
 // that rules are returned in by the API.
 //
 // Rule types can be determined using a type switch:
-//   switch v := rule.(type) {
+//
-//   case RecordingRule:
+//	switch v := rule.(type) {
-//   	fmt.Print("got a recording rule")
+//	case RecordingRule:
-//   case AlertingRule:
+//		fmt.Print("got a recording rule")
-//   	fmt.Print("got a alerting rule")
+//	case AlertingRule:
-//   default:
+//		fmt.Print("got a alerting rule")
-//   	fmt.Printf("unknown rule type %s", v)
+//	default:
-//   }
+//		fmt.Printf("unknown rule type %s", v)
+//	}
 type Rules []interface{}
 
 // AlertingRule models a alerting rule.
@@ -699,7 +699,7 @@ func (h *httpAPI) Config(ctx context.Context) (ConfigResult, error) {
 	return res, json.Unmarshal(body, &res)
 }
 
-func (h *httpAPI) DeleteSeries(ctx context.Context, matches []string, startTime time.Time, endTime time.Time) error {
+func (h *httpAPI) DeleteSeries(ctx context.Context, matches []string, startTime, endTime time.Time) error {
 	u := h.client.URL(epDeleteSeries, nil)
 	q := u.Query()
 
@@ -772,7 +772,7 @@ func (h *httpAPI) Runtimeinfo(ctx context.Context) (RuntimeinfoResult, error) {
 	return res, json.Unmarshal(body, &res)
 }
 
-func (h *httpAPI) LabelNames(ctx context.Context, matches []string, startTime time.Time, endTime time.Time) ([]string, Warnings, error) {
+func (h *httpAPI) LabelNames(ctx context.Context, matches []string, startTime, endTime time.Time) ([]string, Warnings, error) {
 	u := h.client.URL(epLabels, nil)
 	q := u.Query()
 	q.Set("start", formatTime(startTime))
@@ -795,7 +795,7 @@ func (h *httpAPI) LabelNames(ctx context.Context, matches []string, startTime ti
 	return labelNames, w, json.Unmarshal(body, &labelNames)
 }
 
-func (h *httpAPI) LabelValues(ctx context.Context, label string, matches []string, startTime time.Time, endTime time.Time) (model.LabelValues, Warnings, error) {
+func (h *httpAPI) LabelValues(ctx context.Context, label string, matches []string, startTime, endTime time.Time) (model.LabelValues, Warnings, error) {
 	u := h.client.URL(epLabelValues, map[string]string{"name": label})
 	q := u.Query()
 	q.Set("start", formatTime(startTime))
@@ -818,10 +818,34 @@ func (h *httpAPI) LabelValues(ctx context.Context, label string, matches []strin
 	return labelValues, w, json.Unmarshal(body, &labelValues)
 }
 
-func (h *httpAPI) Query(ctx context.Context, query string, ts time.Time) (model.Value, Warnings, error) {
+type apiOptions struct {
+	timeout time.Duration
+}
+
+type Option func(c *apiOptions)
+
+// WithTimeout can be used to provide an optional query evaluation timeout for Query and QueryRange.
+// https://prometheus.io/docs/prometheus/latest/querying/api/#instant-queries
+func WithTimeout(timeout time.Duration) Option {
+	return func(o *apiOptions) {
+		o.timeout = timeout
+	}
+}
+
+func (h *httpAPI) Query(ctx context.Context, query string, ts time.Time, opts ...Option) (model.Value, Warnings, error) {
 	u := h.client.URL(epQuery, nil)
 	q := u.Query()
 
+	opt := &apiOptions{}
+	for _, o := range opts {
+		o(opt)
+	}
+
+	d := opt.timeout
+	if d > 0 {
+		q.Set("timeout", d.String())
+	}
+
 	q.Set("query", query)
 	if !ts.IsZero() {
 		q.Set("time", formatTime(ts))
@@ -833,10 +857,10 @@ func (h *httpAPI) Query(ctx context.Context, query string, ts time.Time) (model.
 	}
 
 	var qres queryResult
-	return model.Value(qres.v), warnings, json.Unmarshal(body, &qres)
+	return qres.v, warnings, json.Unmarshal(body, &qres)
 }
 
-func (h *httpAPI) QueryRange(ctx context.Context, query string, r Range) (model.Value, Warnings, error) {
+func (h *httpAPI) QueryRange(ctx context.Context, query string, r Range, opts ...Option) (model.Value, Warnings, error) {
 	u := h.client.URL(epQueryRange, nil)
 	q := u.Query()
 
@@ -845,6 +869,16 @@ func (h *httpAPI) QueryRange(ctx context.Context, query string, r Range) (model.
 	q.Set("end", formatTime(r.End))
 	q.Set("step", strconv.FormatFloat(r.Step.Seconds(), 'f', -1, 64))
 
+	opt := &apiOptions{}
+	for _, o := range opts {
+		o(opt)
+	}
+
+	d := opt.timeout
+	if d > 0 {
+		q.Set("timeout", d.String())
+	}
+
 	_, body, warnings, err := h.client.DoGetFallback(ctx, u, q)
 	if err != nil {
 		return nil, warnings, err
@@ -852,10 +886,10 @@ func (h *httpAPI) QueryRange(ctx context.Context, query string, r Range) (model.
 
 	var qres queryResult
 
-	return model.Value(qres.v), warnings, json.Unmarshal(body, &qres)
+	return qres.v, warnings, json.Unmarshal(body, &qres)
 }
 
-func (h *httpAPI) Series(ctx context.Context, matches []string, startTime time.Time, endTime time.Time) ([]model.LabelSet, Warnings, error) {
+func (h *httpAPI) Series(ctx context.Context, matches []string, startTime, endTime time.Time) ([]model.LabelSet, Warnings, error) {
 	u := h.client.URL(epSeries, nil)
 	q := u.Query()
 
@@ -938,7 +972,7 @@ func (h *httpAPI) Targets(ctx context.Context) (TargetsResult, error) {
 	return res, json.Unmarshal(body, &res)
 }
 
-func (h *httpAPI) TargetsMetadata(ctx context.Context, matchTarget string, metric string, limit string) ([]MetricMetadata, error) {
+func (h *httpAPI) TargetsMetadata(ctx context.Context, matchTarget, metric, limit string) ([]MetricMetadata, error) {
 	u := h.client.URL(epTargetsMetadata, nil)
 	q := u.Query()
 
@@ -962,7 +996,7 @@ func (h *httpAPI) TargetsMetadata(ctx context.Context, matchTarget string, metri
 	return res, json.Unmarshal(body, &res)
 }
 
-func (h *httpAPI) Metadata(ctx context.Context, metric string, limit string) (map[string][]Metadata, error) {
+func (h *httpAPI) Metadata(ctx context.Context, metric, limit string) (map[string][]Metadata, error) {
 	u := h.client.URL(epMetadata, nil)
 	q := u.Query()
 
@@ -1019,7 +1053,7 @@ func (h *httpAPI) WalReplay(ctx context.Context) (WalReplayStatus, error) {
 	return res, json.Unmarshal(body, &res)
 }
 
-func (h *httpAPI) QueryExemplars(ctx context.Context, query string, startTime time.Time, endTime time.Time) ([]ExemplarQueryResult, error) {
+func (h *httpAPI) QueryExemplars(ctx context.Context, query string, startTime, endTime time.Time) ([]ExemplarQueryResult, error) {
 	u := h.client.URL(epQueryExemplars, nil)
 	q := u.Query()
 
@@ -1127,33 +1161,36 @@ func (h *apiClientImpl) Do(ctx context.Context, req *http.Request) (*http.Respon
 	}
 
 	return resp, []byte(result.Data), result.Warnings, err
-
 }
 
 // DoGetFallback will attempt to do the request as-is, and on a 405 or 501 it
 // will fallback to a GET request.
 func (h *apiClientImpl) DoGetFallback(ctx context.Context, u *url.URL, args url.Values) (*http.Response, []byte, Warnings, error) {
-	req, err := http.NewRequest(http.MethodPost, u.String(), strings.NewReader(args.Encode()))
+	encodedArgs := args.Encode()
+	req, err := http.NewRequest(http.MethodPost, u.String(), strings.NewReader(encodedArgs))
 	if err != nil {
 		return nil, nil, nil, err
 	}
 	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	// Following comment originates from https://pkg.go.dev/net/http#Transport
+	// Transport only retries a request upon encountering a network error if the request is
+	// idempotent and either has no body or has its Request.GetBody defined. HTTP requests
+	// are considered idempotent if they have HTTP methods GET, HEAD, OPTIONS, or TRACE; or
+	// if their Header map contains an "Idempotency-Key" or "X-Idempotency-Key" entry. If the
+	// idempotency key value is a zero-length slice, the request is treated as idempotent but
+	// the header is not sent on the wire.
+	req.Header["Idempotency-Key"] = nil
 
 	resp, body, warnings, err := h.Do(ctx, req)
 	if resp != nil && (resp.StatusCode == http.StatusMethodNotAllowed || resp.StatusCode == http.StatusNotImplemented) {
-		u.RawQuery = args.Encode()
+		u.RawQuery = encodedArgs
 		req, err = http.NewRequest(http.MethodGet, u.String(), nil)
 		if err != nil {
 			return nil, nil, warnings, err
 		}
-
+		return h.Do(ctx, req)
-	} else {
-		if err != nil {
-			return resp, body, warnings, err
-		}
-		return resp, body, warnings, nil
 	}
-	return h.Do(ctx, req)
+	return resp, body, warnings, err
 }
 
 func formatTime(t time.Time) string {

api/prometheus/v1/api_test.go

@@ -17,7 +17,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"math"
 	"net/http"
 	"net/http/httptest"
@@ -40,10 +40,8 @@ type apiTest struct {
 	inRes        interface{}
 
 	reqPath   string
-	reqParam  url.Values
 	reqMethod string
 	res       interface{}
-	warnings  Warnings
 	err       error
 }
 
@@ -55,7 +53,7 @@ type apiTestClient struct {
 func (c *apiTestClient) URL(ep string, args map[string]string) *url.URL {
 	path := ep
 	for k, v := range args {
-		path = strings.Replace(path, ":"+k, v, -1)
+		path = strings.ReplaceAll(path, ":"+k, v)
 	}
 	u := &url.URL{
 		Host: "test:9090",
@@ -64,8 +62,7 @@ func (c *apiTestClient) URL(ep string, args map[string]string) *url.URL {
 	return u
 }
 
-func (c *apiTestClient) Do(ctx context.Context, req *http.Request) (*http.Response, []byte, Warnings, error) {
+func (c *apiTestClient) Do(_ context.Context, req *http.Request) (*http.Response, []byte, Warnings, error) {
-
 	test := c.curTest
 
 	if req.URL.Path != test.reqPath {
@@ -101,7 +98,6 @@ func (c *apiTestClient) DoGetFallback(ctx context.Context, u *url.URL, args url.
 }
 
 func TestAPIs(t *testing.T) {
-
 	testTime := time.Now()
 
 	tc := &apiTestClient{
@@ -131,7 +127,7 @@ func TestAPIs(t *testing.T) {
 		}
 	}
 
-	doDeleteSeries := func(matcher string, startTime time.Time, endTime time.Time) func() (interface{}, Warnings, error) {
+	doDeleteSeries := func(matcher string, startTime, endTime time.Time) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
 			return nil, nil, promAPI.DeleteSeries(context.Background(), []string{matcher}, startTime, endTime)
 		}
@@ -158,31 +154,31 @@ func TestAPIs(t *testing.T) {
 		}
 	}
 
-	doLabelNames := func(matches []string) func() (interface{}, Warnings, error) {
+	doLabelNames := func(matches []string, startTime, endTime time.Time) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
-			return promAPI.LabelNames(context.Background(), matches, time.Now().Add(-100*time.Hour), time.Now())
+			return promAPI.LabelNames(context.Background(), matches, startTime, endTime)
 		}
 	}
 
-	doLabelValues := func(matches []string, label string) func() (interface{}, Warnings, error) {
+	doLabelValues := func(matches []string, label string, startTime, endTime time.Time) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
-			return promAPI.LabelValues(context.Background(), label, matches, time.Now().Add(-100*time.Hour), time.Now())
+			return promAPI.LabelValues(context.Background(), label, matches, startTime, endTime)
 		}
 	}
 
-	doQuery := func(q string, ts time.Time) func() (interface{}, Warnings, error) {
+	doQuery := func(q string, ts time.Time, opts ...Option) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
-			return promAPI.Query(context.Background(), q, ts)
+			return promAPI.Query(context.Background(), q, ts, opts...)
 		}
 	}
 
-	doQueryRange := func(q string, rng Range) func() (interface{}, Warnings, error) {
+	doQueryRange := func(q string, rng Range, opts ...Option) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
-			return promAPI.QueryRange(context.Background(), q, rng)
+			return promAPI.QueryRange(context.Background(), q, rng, opts...)
 		}
 	}
 
-	doSeries := func(matcher string, startTime time.Time, endTime time.Time) func() (interface{}, Warnings, error) {
+	doSeries := func(matcher string, startTime, endTime time.Time) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
 			return promAPI.Series(context.Background(), []string{matcher}, startTime, endTime)
 		}
@@ -209,14 +205,14 @@ func TestAPIs(t *testing.T) {
 		}
 	}
 
-	doTargetsMetadata := func(matchTarget string, metric string, limit string) func() (interface{}, Warnings, error) {
+	doTargetsMetadata := func(matchTarget, metric, limit string) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
 			v, err := promAPI.TargetsMetadata(context.Background(), matchTarget, metric, limit)
 			return v, nil, err
 		}
 	}
 
-	doMetadata := func(metric string, limit string) func() (interface{}, Warnings, error) {
+	doMetadata := func(metric, limit string) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
 			v, err := promAPI.Metadata(context.Background(), metric, limit)
 			return v, nil, err
@@ -237,7 +233,7 @@ func TestAPIs(t *testing.T) {
 		}
 	}
 
-	doQueryExemplars := func(query string, startTime time.Time, endTime time.Time) func() (interface{}, Warnings, error) {
+	doQueryExemplars := func(query string, startTime, endTime time.Time) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
 			v, err := promAPI.QueryExemplars(context.Background(), query, startTime, endTime)
 			return v, nil, err
@@ -246,7 +242,7 @@ func TestAPIs(t *testing.T) {
 
 	queryTests := []apiTest{
 		{
-			do: doQuery("2", testTime),
+			do: doQuery("2", testTime, WithTimeout(5*time.Second)),
 			inRes: &queryResult{
 				Type: model.ValScalar,
 				Result: &model.Scalar{
@@ -257,10 +253,6 @@ func TestAPIs(t *testing.T) {
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query",
-			reqParam: url.Values{
-				"query": []string{"2"},
-				"time":  []string{testTime.Format(time.RFC3339Nano)},
-			},
 			res: &model.Scalar{
 				Value:     2,
 				Timestamp: model.TimeFromUnix(testTime.Unix()),
@@ -272,11 +264,7 @@ func TestAPIs(t *testing.T) {
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query",
-			reqParam: url.Values{
+			err:       errors.New("some error"),
-				"query": []string{"2"},
-				"time":  []string{testTime.Format(time.RFC3339Nano)},
-			},
-			err: fmt.Errorf("some error"),
 		},
 		{
 			do:           doQuery("2", testTime),
@@ -290,11 +278,7 @@ func TestAPIs(t *testing.T) {
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query",
-			reqParam: url.Values{
+			err:       errors.New("server_error: server error: 500"),
-				"query": []string{"2"},
-				"time":  []string{testTime.Format(time.RFC3339Nano)},
-			},
-			err: errors.New("server_error: server error: 500"),
 		},
 		{
 			do:           doQuery("2", testTime),
@@ -308,11 +292,7 @@ func TestAPIs(t *testing.T) {
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query",
-			reqParam: url.Values{
+			err:       errors.New("client_error: client error: 404"),
-				"query": []string{"2"},
-				"time":  []string{testTime.Format(time.RFC3339Nano)},
-			},
-			err: errors.New("client_error: client error: 404"),
 		},
 		// Warning only.
 		{
@@ -328,15 +308,10 @@ func TestAPIs(t *testing.T) {
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query",
-			reqParam: url.Values{
-				"query": []string{"2"},
-				"time":  []string{testTime.Format(time.RFC3339Nano)},
-			},
 			res: &model.Scalar{
 				Value:     2,
 				Timestamp: model.TimeFromUnix(testTime.Unix()),
 			},
-			warnings: []string{"warning"},
 		},
 		// Warning + error.
 		{
@@ -352,114 +327,97 @@ func TestAPIs(t *testing.T) {
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query",
-			reqParam: url.Values{
+			err:       errors.New("client_error: client error: 404"),
-				"query": []string{"2"},
-				"time":  []string{testTime.Format(time.RFC3339Nano)},
-			},
-			err:      errors.New("client_error: client error: 404"),
-			warnings: []string{"warning"},
 		},
 
 		{
 			do: doQueryRange("2", Range{
 				Start: testTime.Add(-time.Minute),
 				End:   testTime,
-				Step:  time.Minute,
+				Step:  1 * time.Minute,
-			}),
+			}, WithTimeout(5*time.Second)),
 			inErr: fmt.Errorf("some error"),
 
 			reqMethod: "POST",
 			reqPath:   "/api/v1/query_range",
-			reqParam: url.Values{
+			err:       errors.New("some error"),
-				"query": []string{"2"},
-				"start": []string{testTime.Add(-time.Minute).Format(time.RFC3339Nano)},
-				"end":   []string{testTime.Format(time.RFC3339Nano)},
-				"step":  []string{time.Minute.String()},
-			},
-			err: fmt.Errorf("some error"),
 		},
 
 		{
-			do:        doLabelNames(nil),
+			do:        doLabelNames(nil, testTime.Add(-100*time.Hour), testTime),
 			inRes:     []string{"val1", "val2"},
 			reqMethod: "GET",
 			reqPath:   "/api/v1/labels",
 			res:       []string{"val1", "val2"},
 		},
 		{
-			do:         doLabelNames(nil),
+			do:         doLabelNames(nil, testTime.Add(-100*time.Hour), testTime),
 			inRes:      []string{"val1", "val2"},
 			inWarnings: []string{"a"},
 			reqMethod:  "GET",
 			reqPath:    "/api/v1/labels",
 			res:        []string{"val1", "val2"},
-			warnings:   []string{"a"},
 		},
 
 		{
-			do:        doLabelNames(nil),
+			do:        doLabelNames(nil, testTime.Add(-100*time.Hour), testTime),
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/labels",
-			err:       fmt.Errorf("some error"),
+			err:       errors.New("some error"),
 		},
 		{
-			do:         doLabelNames(nil),
+			do:         doLabelNames(nil, testTime.Add(-100*time.Hour), testTime),
 			inErr:      fmt.Errorf("some error"),
 			inWarnings: []string{"a"},
 			reqMethod:  "GET",
 			reqPath:    "/api/v1/labels",
-			err:        fmt.Errorf("some error"),
+			err:        errors.New("some error"),
-			warnings:   []string{"a"},
 		},
 		{
-			do:        doLabelNames([]string{"up"}),
+			do:        doLabelNames([]string{"up"}, testTime.Add(-100*time.Hour), testTime),
 			inRes:     []string{"val1", "val2"},
 			reqMethod: "GET",
 			reqPath:   "/api/v1/labels",
-			reqParam:  url.Values{"match[]": {"up"}},
 			res:       []string{"val1", "val2"},
 		},
 
 		{
-			do:        doLabelValues(nil, "mylabel"),
+			do:        doLabelValues(nil, "mylabel", testTime.Add(-100*time.Hour), testTime),
 			inRes:     []string{"val1", "val2"},
 			reqMethod: "GET",
 			reqPath:   "/api/v1/label/mylabel/values",
 			res:       model.LabelValues{"val1", "val2"},
 		},
 		{
-			do:         doLabelValues(nil, "mylabel"),
+			do:         doLabelValues(nil, "mylabel", testTime.Add(-100*time.Hour), testTime),
 			inRes:      []string{"val1", "val2"},
 			inWarnings: []string{"a"},
 			reqMethod:  "GET",
 			reqPath:    "/api/v1/label/mylabel/values",
 			res:        model.LabelValues{"val1", "val2"},
-			warnings:   []string{"a"},
 		},
 
 		{
-			do:        doLabelValues(nil, "mylabel"),
+			do:        doLabelValues(nil, "mylabel", testTime.Add(-100*time.Hour), testTime),
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/label/mylabel/values",
-			err:       fmt.Errorf("some error"),
+			err:       errors.New("some error"),
 		},
 		{
-			do:         doLabelValues(nil, "mylabel"),
+			do:         doLabelValues(nil, "mylabel", testTime.Add(-100*time.Hour), testTime),
 			inErr:      fmt.Errorf("some error"),
 			inWarnings: []string{"a"},
 			reqMethod:  "GET",
 			reqPath:    "/api/v1/label/mylabel/values",
-			err:        fmt.Errorf("some error"),
+			err:        errors.New("some error"),
-			warnings:   []string{"a"},
 		},
 		{
-			do:        doLabelValues([]string{"up"}, "mylabel"),
+			do:        doLabelValues([]string{"up"}, "mylabel", testTime.Add(-100*time.Hour), testTime),
 			inRes:     []string{"val1", "val2"},
 			reqMethod: "GET",
 			reqPath:   "/api/v1/label/mylabel/values",
-			reqParam:  url.Values{"match[]": {"up"}},
 			res:       model.LabelValues{"val1", "val2"},
 		},
 
@@ -469,15 +427,11 @@ func TestAPIs(t *testing.T) {
 				{
 					"__name__": "up",
 					"job":      "prometheus",
-					"instance": "localhost:9090"},
+					"instance": "localhost:9090",
+				},
 			},
 			reqMethod: "GET",
 			reqPath:   "/api/v1/series",
-			reqParam: url.Values{
-				"match": []string{"up"},
-				"start": []string{testTime.Add(-time.Minute).Format(time.RFC3339Nano)},
-				"end":   []string{testTime.Format(time.RFC3339Nano)},
-			},
 			res: []model.LabelSet{
 				{
 					"__name__": "up",
@@ -493,16 +447,12 @@ func TestAPIs(t *testing.T) {
 				{
 					"__name__": "up",
 					"job":      "prometheus",
-					"instance": "localhost:9090"},
+					"instance": "localhost:9090",
+				},
 			},
 			inWarnings: []string{"a"},
 			reqMethod:  "GET",
 			reqPath:    "/api/v1/series",
-			reqParam: url.Values{
-				"match": []string{"up"},
-				"start": []string{testTime.Add(-time.Minute).Format(time.RFC3339Nano)},
-				"end":   []string{testTime.Format(time.RFC3339Nano)},
-			},
 			res: []model.LabelSet{
 				{
 					"__name__": "up",
@@ -510,7 +460,6 @@ func TestAPIs(t *testing.T) {
 					"instance": "localhost:9090",
 				},
 			},
-			warnings: []string{"a"},
 		},
 
 		{
@@ -518,12 +467,7 @@ func TestAPIs(t *testing.T) {
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/series",
-			reqParam: url.Values{
+			err:       errors.New("some error"),
-				"match": []string{"up"},
-				"start": []string{testTime.Add(-time.Minute).Format(time.RFC3339Nano)},
-				"end":   []string{testTime.Format(time.RFC3339Nano)},
-			},
-			err: fmt.Errorf("some error"),
 		},
 		// Series with error and warning.
 		{
@@ -532,13 +476,7 @@ func TestAPIs(t *testing.T) {
 			inWarnings: []string{"a"},
 			reqMethod:  "GET",
 			reqPath:    "/api/v1/series",
-			reqParam: url.Values{
+			err:        errors.New("some error"),
-				"match": []string{"up"},
-				"start": []string{testTime.Add(-time.Minute).Format(time.RFC3339Nano)},
-				"end":   []string{testTime.Format(time.RFC3339Nano)},
-			},
-			err:      fmt.Errorf("some error"),
-			warnings: []string{"a"},
 		},
 
 		{
@@ -548,9 +486,6 @@ func TestAPIs(t *testing.T) {
 			},
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/snapshot",
-			reqParam: url.Values{
-				"skip_head": []string{"true"},
-			},
 			res: SnapshotResult{
 				Name: "20171210T211224Z-2be650b6d019eb54",
 			},
@@ -561,7 +496,7 @@ func TestAPIs(t *testing.T) {
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/snapshot",
-			err:       fmt.Errorf("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -575,7 +510,7 @@ func TestAPIs(t *testing.T) {
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/clean_tombstones",
-			err:       fmt.Errorf("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -584,15 +519,11 @@ func TestAPIs(t *testing.T) {
 				{
 					"__name__": "up",
 					"job":      "prometheus",
-					"instance": "localhost:9090"},
+					"instance": "localhost:9090",
+				},
 			},
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/delete_series",
-			reqParam: url.Values{
-				"match": []string{"up"},
-				"start": []string{testTime.Add(-time.Minute).Format(time.RFC3339Nano)},
-				"end":   []string{testTime.Format(time.RFC3339Nano)},
-			},
 		},
 
 		{
@@ -600,12 +531,7 @@ func TestAPIs(t *testing.T) {
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "POST",
 			reqPath:   "/api/v1/admin/tsdb/delete_series",
-			reqParam: url.Values{
+			err:       errors.New("some error"),
-				"match": []string{"up"},
-				"start": []string{testTime.Add(-time.Minute).Format(time.RFC3339Nano)},
-				"end":   []string{testTime.Format(time.RFC3339Nano)},
-			},
-			err: fmt.Errorf("some error"),
 		},
 
 		{
@@ -1064,11 +990,6 @@ func TestAPIs(t *testing.T) {
 			},
 			reqMethod: "GET",
 			reqPath:   "/api/v1/targets/metadata",
-			reqParam: url.Values{
-				"match_target": []string{"{job=\"prometheus\"}"},
-				"metric":       []string{"go_goroutines"},
-				"limit":        []string{"1"},
-			},
 			res: []MetricMetadata{
 				{
 					Target: map[string]string{
@@ -1087,12 +1008,7 @@ func TestAPIs(t *testing.T) {
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/targets/metadata",
-			reqParam: url.Values{
+			err:       errors.New("some error"),
-				"match_target": []string{"{job=\"prometheus\"}"},
-				"metric":       []string{"go_goroutines"},
-				"limit":        []string{"1"},
-			},
-			err: fmt.Errorf("some error"),
 		},
 
 		{
@@ -1108,12 +1024,8 @@ func TestAPIs(t *testing.T) {
 			},
 			reqMethod: "GET",
 			reqPath:   "/api/v1/metadata",
-			reqParam: url.Values{
-				"metric": []string{"go_goroutines"},
-				"limit":  []string{"1"},
-			},
 			res: map[string][]Metadata{
-				"go_goroutines": []Metadata{
+				"go_goroutines": {
 					{
 						Type: "gauge",
 						Help: "Number of goroutines that currently exist.",
@@ -1128,11 +1040,7 @@ func TestAPIs(t *testing.T) {
 			inErr:     fmt.Errorf("some error"),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/metadata",
-			reqParam: url.Values{
+			err:       errors.New("some error"),
-				"metric": []string{""},
-				"limit":  []string{"1"},
-			},
-			err: fmt.Errorf("some error"),
 		},
 
 		{
@@ -1243,8 +1151,8 @@ func TestAPIs(t *testing.T) {
 			do:        doQueryExemplars("tns_request_duration_seconds_bucket", testTime.Add(-1*time.Minute), testTime),
 			reqMethod: "GET",
 			reqPath:   "/api/v1/query_exemplars",
-			inErr:     fmt.Errorf("some error"),
+			inErr:     errors.New("some error"),
-			err:       fmt.Errorf("some error"),
+			err:       errors.New("some error"),
 		},
 
 		{
@@ -1320,7 +1228,9 @@ func TestAPIs(t *testing.T) {
 				if err.Error() != test.err.Error() {
 					t.Errorf("unexpected error: want %s, got %s", test.err, err)
 				}
-				if apiErr, ok := err.(*Error); ok {
+
+				apiErr := &Error{}
+				if ok := errors.As(err, &apiErr); ok {
 					if apiErr.Detail != test.inRes {
 						t.Errorf("%q should be %q", apiErr.Detail, test.inRes)
 					}
@@ -1521,7 +1431,6 @@ func TestAPIClientDo(t *testing.T) {
 
 	for i, test := range tests {
 		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
-
 			tc.ch <- test
 
 			_, body, warnings, err := client.Do(context.Background(), tc.req)
@@ -1546,9 +1455,13 @@ func TestAPIClientDo(t *testing.T) {
 				}
 
 				if test.expectedErr.Detail != "" {
-					apiErr := err.(*Error)
+					apiErr := &Error{}
-					if apiErr.Detail != test.expectedErr.Detail {
+					if errors.As(err, &apiErr) {
-						t.Fatalf("expected error detail :%v, but got:%v", apiErr.Detail, test.expectedErr.Detail)
+						if apiErr.Detail != test.expectedErr.Detail {
+							t.Fatalf("expected error detail :%v, but got:%v", apiErr.Detail, test.expectedErr.Detail)
+						}
+					} else {
+						t.Fatalf("expected v1.Error instance, but got:%T", err)
 					}
 				}
 
@@ -1562,7 +1475,6 @@ func TestAPIClientDo(t *testing.T) {
 				t.Fatalf("expected body :%v, but got:%v", test.expectedBody, string(body))
 			}
 		})
-
 	}
 }
 
@@ -1679,7 +1591,7 @@ func (c *httpTestClient) Do(ctx context.Context, req *http.Request) (*http.Respo
 	var body []byte
 	done := make(chan struct{})
 	go func() {
-		body, err = ioutil.ReadAll(resp.Body)
+		body, err = io.ReadAll(resp.Body)
 		close(done)
 	}()
 

api/prometheus/v1/example_test.go

@@ -22,9 +22,10 @@ import (
 	"os"
 	"time"
 
-	"github.com/prometheus/client_golang/api"
-	v1 "github.com/prometheus/client_golang/api/prometheus/v1"
 	"github.com/prometheus/common/config"
+
+	"git.internal/re/client_golang/api"
+	v1 "git.internal/re/client_golang/api/prometheus/v1"
 )
 
 func ExampleAPI_query() {
@@ -39,7 +40,7 @@ func ExampleAPI_query() {
 	v1api := v1.NewAPI(client)
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
-	result, warnings, err := v1api.Query(ctx, "up", time.Now())
+	result, warnings, err := v1api.Query(ctx, "up", time.Now(), v1.WithTimeout(5*time.Second))
 	if err != nil {
 		fmt.Printf("Error querying Prometheus: %v\n", err)
 		os.Exit(1)
@@ -67,7 +68,7 @@ func ExampleAPI_queryRange() {
 		End:   time.Now(),
 		Step:  time.Minute,
 	}
-	result, warnings, err := v1api.QueryRange(ctx, "rate(prometheus_tsdb_head_samples_appended_total[5m])", r)
+	result, warnings, err := v1api.QueryRange(ctx, "rate(prometheus_tsdb_head_samples_appended_total[5m])", r, v1.WithTimeout(5*time.Second))
 	if err != nil {
 		fmt.Printf("Error querying Prometheus: %v\n", err)
 		os.Exit(1)

examples/exemplars/main.go

@@ -0,0 +1,69 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// A simple example of how to record a latency metric with exemplars, using a fictional id
+// as a prometheus label.
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"math/rand"
+	"net/http"
+	"time"
+
+	"git.internal/re/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus/collectors"
+	"git.internal/re/client_golang/prometheus/promhttp"
+)
+
+func main() {
+	requestDurations := prometheus.NewHistogram(prometheus.HistogramOpts{
+		Name:    "http_request_duration_seconds",
+		Help:    "A histogram of the HTTP request durations in seconds.",
+		Buckets: prometheus.ExponentialBuckets(0.1, 1.5, 5),
+	})
+
+	// Create non-global registry.
+	registry := prometheus.NewRegistry()
+
+	// Add go runtime metrics and process collectors.
+	registry.MustRegister(
+		collectors.NewGoCollector(),
+		collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}),
+		requestDurations,
+	)
+
+	go func() {
+		for {
+			// Record fictional latency.
+			now := time.Now()
+			requestDurations.(prometheus.ExemplarObserver).ObserveWithExemplar(
+				time.Since(now).Seconds(), prometheus.Labels{"dummyID": fmt.Sprint(rand.Intn(100000))},
+			)
+			time.Sleep(600 * time.Millisecond)
+		}
+	}()
+
+	// Expose /metrics HTTP endpoint using the created custom registry.
+	http.Handle(
+		"/metrics", promhttp.HandlerFor(
+			registry,
+			promhttp.HandlerOpts{
+				EnableOpenMetrics: true,
+			}),
+	)
+	// To test: curl -H 'Accept: application/openmetrics-text' localhost:8080/metrics
+	log.Fatalln(http.ListenAndServe(":8080", nil))
+}

examples/gocollector/main.go

@@ -22,10 +22,11 @@ import (
 	"fmt"
 	"log"
 	"net/http"
+	"regexp"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/collectors"
+	"git.internal/re/client_golang/prometheus/collectors"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"git.internal/re/client_golang/prometheus/promhttp"
 )
 
 var addr = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
@@ -39,7 +40,7 @@ func main() {
 	// Add Go module build info.
 	reg.MustRegister(collectors.NewBuildInfoCollector())
 	reg.MustRegister(collectors.NewGoCollector(
-		collectors.WithGoCollections(collectors.GoRuntimeMemStatsCollection | collectors.GoRuntimeMetricsCollection),
+		collectors.WithGoCollectorRuntimeMetrics(collectors.GoRuntimeMetricsRule{Matcher: regexp.MustCompile("/.*")}),
 	))
 
 	// Expose the registered metrics via HTTP.

examples/middleware/go.mod

@@ -0,0 +1,17 @@
+module github.com/jessicalins/instrumentation-practices-examples/middleware
+
+go 1.17
+
+require git.internal/re/client_golang v1.13.1
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
+	github.com/prometheus/client_model v0.2.0 // indirect
+	github.com/prometheus/common v0.37.0 // indirect
+	github.com/prometheus/procfs v0.8.0 // indirect
+	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)

examples/middleware/go.sum

@@ -0,0 +1,477 @@
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+honnef.co/go/tools v0.0.1-2019.2.3/go.mod h1:a3bituU0lyd329TUQxRnasdCoJDkEUEAqEt0JzvZhAg=
+honnef.co/go/tools v0.0.1-2020.1.3/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9vFzvIQ3k=
+honnef.co/go/tools v0.0.1-2020.1.4/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9vFzvIQ3k=
+rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=
+rsc.io/quote/v3 v3.1.0/go.mod h1:yEA65RcK8LyAZtP9Kv3t0HmxON59tX3rD+tICJqUlj0=
+rsc.io/sampler v1.3.0/go.mod h1:T1hPZKmBbMNahiBKFy5HrXp6adAjACjK9JXDnKaTXpA=

examples/middleware/httpmiddleware/httpmiddleware.go

@@ -0,0 +1,103 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package httpmiddleware is adapted from
+// https://github.com/bwplotka/correlator/tree/main/examples/observability/ping/pkg/httpinstrumentation
+package httpmiddleware
+
+import (
+	"net/http"
+
+	"git.internal/re/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus/promauto"
+	"git.internal/re/client_golang/prometheus/promhttp"
+)
+
+type Middleware interface {
+	// WrapHandler wraps the given HTTP handler for instrumentation.
+	WrapHandler(handlerName string, handler http.Handler) http.HandlerFunc
+}
+
+type middleware struct {
+	buckets  []float64
+	registry prometheus.Registerer
+}
+
+// WrapHandler wraps the given HTTP handler for instrumentation:
+// It registers four metric collectors (if not already done) and reports HTTP
+// metrics to the (newly or already) registered collectors.
+// Each has a constant label named "handler" with the provided handlerName as
+// value.
+func (m *middleware) WrapHandler(handlerName string, handler http.Handler) http.HandlerFunc {
+	reg := prometheus.WrapRegistererWith(prometheus.Labels{"handler": handlerName}, m.registry)
+
+	requestsTotal := promauto.With(reg).NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "http_requests_total",
+			Help: "Tracks the number of HTTP requests.",
+		}, []string{"method", "code"},
+	)
+	requestDuration := promauto.With(reg).NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "http_request_duration_seconds",
+			Help:    "Tracks the latencies for HTTP requests.",
+			Buckets: m.buckets,
+		},
+		[]string{"method", "code"},
+	)
+	requestSize := promauto.With(reg).NewSummaryVec(
+		prometheus.SummaryOpts{
+			Name: "http_request_size_bytes",
+			Help: "Tracks the size of HTTP requests.",
+		},
+		[]string{"method", "code"},
+	)
+	responseSize := promauto.With(reg).NewSummaryVec(
+		prometheus.SummaryOpts{
+			Name: "http_response_size_bytes",
+			Help: "Tracks the size of HTTP responses.",
+		},
+		[]string{"method", "code"},
+	)
+
+	// Wraps the provided http.Handler to observe the request result with the provided metrics.
+	base := promhttp.InstrumentHandlerCounter(
+		requestsTotal,
+		promhttp.InstrumentHandlerDuration(
+			requestDuration,
+			promhttp.InstrumentHandlerRequestSize(
+				requestSize,
+				promhttp.InstrumentHandlerResponseSize(
+					responseSize,
+					http.HandlerFunc(func(writer http.ResponseWriter, r *http.Request) {
+						handler.ServeHTTP(writer, r)
+					}),
+				),
+			),
+		),
+	)
+
+	return base.ServeHTTP
+}
+
+// New returns a Middleware interface.
+func New(registry prometheus.Registerer, buckets []float64) Middleware {
+	if buckets == nil {
+		buckets = prometheus.ExponentialBuckets(0.1, 1.5, 5)
+	}
+
+	return &middleware{
+		buckets:  buckets,
+		registry: registry,
+	}
+}

examples/middleware/main.go

@@ -0,0 +1,50 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Simple example of auto-instrumentation by using an HTTP Middleware with relevant metrics.
+
+package main
+
+import (
+	"log"
+	"net/http"
+
+	"git.internal/re/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus/collectors"
+	"git.internal/re/client_golang/prometheus/promhttp"
+
+	"github.com/jessicalins/instrumentation-practices-examples/middleware/httpmiddleware"
+)
+
+func main() {
+	// Create non-global registry.
+	registry := prometheus.NewRegistry()
+
+	// Add go runtime metrics and process collectors.
+	registry.MustRegister(
+		collectors.NewGoCollector(),
+		collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}),
+	)
+
+	// Expose /metrics HTTP endpoint using the created custom registry.
+	http.Handle(
+		"/metrics",
+		httpmiddleware.New(
+			registry, nil).
+			WrapHandler("/metrics", promhttp.HandlerFor(
+				registry,
+				promhttp.HandlerOpts{}),
+			))
+
+	log.Fatalln(http.ListenAndServe(":8080", nil))
+}

examples/random/main.go

@@ -25,11 +25,52 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/collectors"
+	"git.internal/re/client_golang/prometheus/collectors"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"git.internal/re/client_golang/prometheus/promhttp"
 )
 
+type metrics struct {
+	rpcDurations          *prometheus.SummaryVec
+	rpcDurationsHistogram prometheus.Histogram
+}
+
+func NewMetrics(reg prometheus.Registerer, normMean, normDomain float64) *metrics {
+	m := &metrics{
+		// Create a summary to track fictional inter service RPC latencies for three
+		// distinct services with different latency distributions. These services are
+		// differentiated via a "service" label.
+		rpcDurations: prometheus.NewSummaryVec(
+			prometheus.SummaryOpts{
+				Name:       "rpc_durations_seconds",
+				Help:       "RPC latency distributions.",
+				Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+			},
+			[]string{"service"},
+		),
+		// The same as above, but now as a histogram, and only for the
+		// normal distribution. The histogram features both conventional
+		// buckets as well as sparse buckets, the latter needed for the
+		// experimental native histograms (ingested by a Prometheus
+		// server v2.40 with the corresponding feature flag
+		// enabled). The conventional buckets are targeted to the
+		// parameters of the normal distribution, with 20 buckets
+		// centered on the mean, each half-sigma wide. The sparse
+		// buckets are always centered on zero, with a growth factor of
+		// one bucket to the next of (at most) 1.1. (The precise factor
+		// is 2^2^-3 = 1.0905077...)
+		rpcDurationsHistogram: prometheus.NewHistogram(prometheus.HistogramOpts{
+			Name:                        "rpc_durations_histogram_seconds",
+			Help:                        "RPC latency distributions.",
+			Buckets:                     prometheus.LinearBuckets(normMean-5*normDomain, .5*normDomain, 20),
+			NativeHistogramBucketFactor: 1.1,
+		}),
+	}
+	reg.MustRegister(m.rpcDurations)
+	reg.MustRegister(m.rpcDurationsHistogram)
+	return m
+}
+
 func main() {
 	var (
 		addr              = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
@@ -41,34 +82,13 @@ func main() {
 
 	flag.Parse()
 
-	var (
+	// Create a non-global registry.
-		// Create a summary to track fictional interservice RPC latencies for three
+	reg := prometheus.NewRegistry()
-		// distinct services with different latency distributions. These services are
-		// differentiated via a "service" label.
-		rpcDurations = prometheus.NewSummaryVec(
-			prometheus.SummaryOpts{
-				Name:       "rpc_durations_seconds",
-				Help:       "RPC latency distributions.",
-				Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
-			},
-			[]string{"service"},
-		)
-		// The same as above, but now as a histogram, and only for the normal
-		// distribution. The buckets are targeted to the parameters of the
-		// normal distribution, with 20 buckets centered on the mean, each
-		// half-sigma wide.
-		rpcDurationsHistogram = prometheus.NewHistogram(prometheus.HistogramOpts{
-			Name:    "rpc_durations_histogram_seconds",
-			Help:    "RPC latency distributions.",
-			Buckets: prometheus.LinearBuckets(*normMean-5**normDomain, .5**normDomain, 20),
-		})
-	)
 
-	// Register the summary and the histogram with Prometheus's default registry.
+	// Create new metrics and register them using the custom registry.
-	prometheus.MustRegister(rpcDurations)
+	m := NewMetrics(reg, *normMean, *normDomain)
-	prometheus.MustRegister(rpcDurationsHistogram)
 	// Add Go module build info.
-	prometheus.MustRegister(collectors.NewBuildInfoCollector())
+	reg.MustRegister(collectors.NewBuildInfoCollector())
 
 	start := time.Now()
 
@@ -80,7 +100,7 @@ func main() {
 	go func() {
 		for {
 			v := rand.Float64() * *uniformDomain
-			rpcDurations.WithLabelValues("uniform").Observe(v)
+			m.rpcDurations.WithLabelValues("uniform").Observe(v)
 			time.Sleep(time.Duration(100*oscillationFactor()) * time.Millisecond)
 		}
 	}()
@@ -88,14 +108,14 @@ func main() {
 	go func() {
 		for {
 			v := (rand.NormFloat64() * *normDomain) + *normMean
-			rpcDurations.WithLabelValues("normal").Observe(v)
+			m.rpcDurations.WithLabelValues("normal").Observe(v)
 			// Demonstrate exemplar support with a dummy ID. This
 			// would be something like a trace ID in a real
 			// application.  Note the necessary type assertion. We
 			// already know that rpcDurationsHistogram implements
 			// the ExemplarObserver interface and thus don't need to
 			// check the outcome of the type assertion.
-			rpcDurationsHistogram.(prometheus.ExemplarObserver).ObserveWithExemplar(
+			m.rpcDurationsHistogram.(prometheus.ExemplarObserver).ObserveWithExemplar(
 				v, prometheus.Labels{"dummyID": fmt.Sprint(rand.Intn(100000))},
 			)
 			time.Sleep(time.Duration(75*oscillationFactor()) * time.Millisecond)
@@ -105,17 +125,19 @@ func main() {
 	go func() {
 		for {
 			v := rand.ExpFloat64() / 1e6
-			rpcDurations.WithLabelValues("exponential").Observe(v)
+			m.rpcDurations.WithLabelValues("exponential").Observe(v)
 			time.Sleep(time.Duration(50*oscillationFactor()) * time.Millisecond)
 		}
 	}()
 
 	// Expose the registered metrics via HTTP.
 	http.Handle("/metrics", promhttp.HandlerFor(
-		prometheus.DefaultGatherer,
+		reg,
 		promhttp.HandlerOpts{
 			// Opt into OpenMetrics to support exemplars.
 			EnableOpenMetrics: true,
+			// Pass custom registry
+			Registry: reg,
 		},
 	))
 	log.Fatal(http.ListenAndServe(*addr, nil))

examples/simple/main.go

@@ -19,13 +19,27 @@ import (
 	"log"
 	"net/http"
 
-	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"git.internal/re/client_golang/prometheus/collectors"
+
+	"git.internal/re/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus/promhttp"
 )
 
 var addr = flag.String("listen-address", ":8080", "The address to listen on for HTTP requests.")
 
 func main() {
 	flag.Parse()
-	http.Handle("/metrics", promhttp.Handler())
+
+	// Create non-global registry.
+	reg := prometheus.NewRegistry()
+
+	// Add go runtime metrics and process collectors.
+	reg.MustRegister(
+		collectors.NewGoCollector(),
+		collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}),
+	)
+
+	// Expose /metrics HTTP endpoint using the created custom registry.
+	http.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{Registry: reg}))
 	log.Fatal(http.ListenAndServe(*addr, nil))
 }

go.mod

@@ -1,15 +1,32 @@
-module github.com/prometheus/client_golang
+module git.internal/re/client_golang
+
+go 1.17
 
 require (
 	github.com/beorn7/perks v1.0.1
 	github.com/cespare/xxhash/v2 v2.1.2
+	github.com/davecgh/go-spew v1.1.1
 	github.com/golang/protobuf v1.5.2
 	github.com/json-iterator/go v1.1.12
-	github.com/prometheus/client_model v0.2.0
+	github.com/prometheus/client_model v0.3.0
-	github.com/prometheus/common v0.32.1
+	github.com/prometheus/common v0.37.0
-	github.com/prometheus/procfs v0.7.3
+	github.com/prometheus/procfs v0.8.0
-	golang.org/x/sys v0.0.0-20220114195835-da31bd327af9
+	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a
-	google.golang.org/protobuf v1.26.0
+	google.golang.org/protobuf v1.28.1
 )
 
-go 1.13
+require (
+	github.com/jpillora/backoff v1.0.0 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f // indirect
+	github.com/prometheus/client_golang v1.12.1 // indirect
+	golang.org/x/net v0.0.0-20220225172249-27dd8689420f // indirect
+	golang.org/x/oauth2 v0.0.0-20220223155221-ee480838109b // indirect
+	golang.org/x/text v0.3.7 // indirect
+	google.golang.org/appengine v1.6.6 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+)
+
+exclude git.internal/re/client_golang v1.12.1

go.sum

@@ -64,9 +64,11 @@ github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2
 github.com/go-kit/kit v0.8.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
 github.com/go-kit/kit v0.9.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
 github.com/go-kit/log v0.1.0/go.mod h1:zbhenjAZHb184qTLMA9ZjW7ThYL0H2mk7Q6pNt4vbaY=
+github.com/go-kit/log v0.2.0/go.mod h1:NwTd00d/i8cPZ3xOwwiv2PO5MOcx78fFErGNcVmBjv0=
 github.com/go-logfmt/logfmt v0.3.0/go.mod h1:Qt1PoO58o5twSAckw1HlFXLmHsOX5/0LbT9GBnD5lWE=
 github.com/go-logfmt/logfmt v0.4.0/go.mod h1:3RMwSq7FuexP4Kalkev3ejPJsZTpXXBr9+V4qmtdjCk=
 github.com/go-logfmt/logfmt v0.5.0/go.mod h1:wCYkCAKZfumFQihp8CzCvQ3paCTfi41vtzG1KdI/P7A=
+github.com/go-logfmt/logfmt v0.5.1/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/gogo/protobuf v1.1.1/go.mod h1:r8qH/GZQm5c6nD/R0oafs1akxWv10x8SbQlK7atdtwQ=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
@@ -107,8 +109,9 @@ github.com/google/go-cmp v0.4.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/google/go-cmp v0.5.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
+github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
 github.com/google/martian/v3 v3.0.0/go.mod h1:y5Zk1BBys9G+gd6Jrk0W3cC1+ELVxBWuIGO+w/tUAp0=
@@ -166,22 +169,27 @@ github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXP
 github.com/prometheus/client_golang v1.0.0/go.mod h1:db9x61etRT2tGnBNRi70OPL5FsnadC4Ky3P0J6CfImo=
 github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP4j5+D6mVACh+pe2M=
 github.com/prometheus/client_golang v1.11.0/go.mod h1:Z6t4BnS23TR94PD6BsDNk8yVqroYurpAkEiz0P2BEV0=
+github.com/prometheus/client_golang v1.12.1 h1:ZiaPsmm9uiBeaSMRznKsCDNtPCS0T3JVDGF+06gjBzk=
+github.com/prometheus/client_golang v1.12.1/go.mod h1:3Z9XVyYiZYEO+YQWt3RD2R3jrbd179Rt297l4aS6nDY=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
 github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
-github.com/prometheus/client_model v0.2.0 h1:uq5h0d+GuxiXLJLNABMgp2qUWDPiLvgCzz2dUR+/W/M=
 github.com/prometheus/client_model v0.2.0/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/prometheus/client_model v0.3.0 h1:UBgGFHqYdG/TPFD1B1ogZywDqEkwp3fBMvqdiQ7Xew4=
+github.com/prometheus/client_model v0.3.0/go.mod h1:LDGWKZIo7rky3hgvBe+caln+Dr3dPggB5dvjtD7w9+w=
 github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y86RQel1bk4=
 github.com/prometheus/common v0.10.0/go.mod h1:Tlit/dnDKsSWFlCLTWaA1cyBgKHSMdTB80sz/V91rCo=
 github.com/prometheus/common v0.26.0/go.mod h1:M7rCNAaPfAosfx8veZJCuw84e35h3Cfd9VFqTh1DIvc=
-github.com/prometheus/common v0.32.1 h1:hWIdL3N2HoUx3B8j3YN9mWor0qhY/NlEKZEaXxuIRh4=
 github.com/prometheus/common v0.32.1/go.mod h1:vu+V0TpY+O6vW9J44gczi3Ap/oXXR10b+M/gUGO4Hls=
+github.com/prometheus/common v0.37.0 h1:ccBbHCgIiT9uSoFY0vX8H3zsNR5eLt17/RQLUvn8pXE=
+github.com/prometheus/common v0.37.0/go.mod h1:phzohg0JFMnBEFGxTDbfu3QyL5GI8gTQJFhYO5B3mfA=
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.2/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=
 github.com/prometheus/procfs v0.1.3/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
 github.com/prometheus/procfs v0.6.0/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
-github.com/prometheus/procfs v0.7.3 h1:4jVXhlkAyzOScmCkXBTOLRLTz8EeU+eyjrwB/EPq0VU=
 github.com/prometheus/procfs v0.7.3/go.mod h1:cz+aTbrPOrUb4q7XlbU9ygM+/jj0fzG6c1xBZuNvfVA=
+github.com/prometheus/procfs v0.8.0 h1:ODq8ZFEaYeCaZOJlZZdJA2AbQR98dSHSM1KW/You5mo=
+github.com/prometheus/procfs v0.8.0/go.mod h1:z7EfXMXOkbkqb9IINtpCn86r/to3BnA0uaxHdg830/4=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
@@ -264,15 +272,18 @@ golang.org/x/net v0.0.0-20200520182314-0ba52f642ac2/go.mod h1:qpuaurCH72eLCgpAm/
 golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20200707034311-ab3426394381/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
-golang.org/x/net v0.0.0-20210525063256-abc453219eb5 h1:wjuX4b5yYQnEQHzd+CBcrcC6OVR2J1CN6mUy0oSxIPo=
 golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
+golang.org/x/net v0.0.0-20220225172249-27dd8689420f h1:oA4XRj0qtSt8Yo1Zms0CUlsT3KG69V2UGQWPBxujDmc=
+golang.org/x/net v0.0.0-20220225172249-27dd8689420f/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20191202225959-858c2ad4c8b6/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
-golang.org/x/oauth2 v0.0.0-20210514164344-f6687ab2804c h1:pkQiBZBvdos9qq4wBAHqlzuZHEXo07pqV06ef90u1WI=
 golang.org/x/oauth2 v0.0.0-20210514164344-f6687ab2804c/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
+golang.org/x/oauth2 v0.0.0-20220223155221-ee480838109b h1:clP8eMhB30EHdc0bd2Twtq6kgU7yl5ub2cQLSdrv1Dg=
+golang.org/x/oauth2 v0.0.0-20220223155221-ee480838109b/go.mod h1:DAh4E804XQdzx2j+YRIaUnCqCV2RuMz24cGBJ5QYIrc=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -282,6 +293,7 @@ golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220601150217-0de741cfad7f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -317,16 +329,21 @@ golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220114195835-da31bd327af9 h1:XfKQ4OlFl8okEOr5UvAqFRVj8pY/4yfcXrddB8qAbU0=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a h1:dGzPydgVsqGcTRVwiLJ1jVbufYwmzD3LfVPLKsKg+0k=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -373,7 +390,6 @@ golang.org/x/tools v0.0.0-20200825202427-b303f430e36d/go.mod h1:njjCfa9FT2d7l9Bc
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/api v0.4.0/go.mod h1:8k5glujaEP+g9n7WNsDg8QP6cUVNI86fCNMcbazEtwE=
 google.golang.org/api v0.7.0/go.mod h1:WtwebWUNSVBH/HAw79HIFXZNqEvBhG+Ra+ax0hx3E3M=
@@ -450,8 +466,9 @@ google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpAD
 google.golang.org/protobuf v1.24.0/go.mod h1:r/3tXBNzIEhYS9I1OUVjXDlt8tc493IdKGjtUeSXeh4=
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
-google.golang.org/protobuf v1.26.0 h1:bxAC2xTBsZGibn2RTntX0oH50xLsqy1OxA9tTL3p/lk=
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.28.1 h1:d0NfwRgPtno5B1Wa6L2DAG+KivqkdutMf1UhdNx175w=
+google.golang.org/protobuf v1.28.1/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

prometheus/README.md

@@ -1 +1 @@
-See [![Go Reference](https://pkg.go.dev/badge/github.com/prometheus/client_golang/prometheus.svg)](https://pkg.go.dev/github.com/prometheus/client_golang/prometheus).
+See [![Go Reference](https://pkg.go.dev/badge/git.internal/re/client_golang/prometheus.svg)](https://pkg.go.dev/git.internal/re/client_golang/prometheus).

prometheus/collector.go

@@ -69,9 +69,9 @@ type Collector interface {
 // If a Collector collects the same metrics throughout its lifetime, its
 // Describe method can simply be implemented as:
 //
-//   func (c customCollector) Describe(ch chan<- *Desc) {
+//	func (c customCollector) Describe(ch chan<- *Desc) {
-//   	DescribeByCollect(c, ch)
+//		DescribeByCollect(c, ch)
-//   }
+//	}
 //
 // However, this will not work if the metrics collected change dynamically over
 // the lifetime of the Collector in a way that their combined set of descriptors

prometheus/collector_test.go

@@ -30,7 +30,6 @@ func (c collectorDescribedByCollect) Describe(ch chan<- *Desc) {
 }
 
 func TestDescribeByCollect(t *testing.T) {
-
 	goodCollector := collectorDescribedByCollect{
 		cnt: NewCounter(CounterOpts{Name: "c1", Help: "help c1"}),
 		gge: NewGauge(GaugeOpts{Name: "g1", Help: "help g1"}),

prometheus/collectors/collectors.go

@@ -15,7 +15,7 @@
 // conveniently collect process and Go-related metrics.
 package collectors
 
-import "github.com/prometheus/client_golang/prometheus"
+import "git.internal/re/client_golang/prometheus"
 
 // NewBuildInfoCollector returns a collector collecting a single metric
 // "go_build_info" with the constant value 1 and three labels "path", "version",
@@ -25,7 +25,7 @@ import "github.com/prometheus/client_golang/prometheus"
 // the source repository (rather than the local file system). This is usually
 // accomplished by building from outside of GOPATH, specifying the full address
 // of the main package, e.g. "GO111MODULE=on go run
-// github.com/prometheus/client_golang/examples/random". If built without Go
+// git.internal/re/client_golang/examples/random". If built without Go
 // module support, all label values will be "unknown". If built with Go module
 // support but using the source code from the local file system, the "path" will
 // be set appropriately, but "checksum" will be empty and "version" will be

prometheus/collectors/dbstats_collector.go

@@ -16,7 +16,7 @@ package collectors
 import (
 	"database/sql"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 type dbStatsCollector struct {
@@ -101,7 +101,7 @@ func (c *dbStatsCollector) Describe(ch chan<- *prometheus.Desc) {
 	ch <- c.waitDuration
 	ch <- c.maxIdleClosed
 	ch <- c.maxLifetimeClosed
-	c.describeNewInGo115(ch)
+	ch <- c.maxIdleTimeClosed
 }
 
 // Collect implements Collector.
@@ -115,5 +115,5 @@ func (c *dbStatsCollector) Collect(ch chan<- prometheus.Metric) {
 	ch <- prometheus.MustNewConstMetric(c.waitDuration, prometheus.CounterValue, stats.WaitDuration.Seconds())
 	ch <- prometheus.MustNewConstMetric(c.maxIdleClosed, prometheus.CounterValue, float64(stats.MaxIdleClosed))
 	ch <- prometheus.MustNewConstMetric(c.maxLifetimeClosed, prometheus.CounterValue, float64(stats.MaxLifetimeClosed))
-	c.collectNewInGo115(ch, stats)
+	ch <- prometheus.MustNewConstMetric(c.maxIdleTimeClosed, prometheus.CounterValue, float64(stats.MaxIdleTimeClosed))
 }

prometheus/collectors/dbstats_collector_test.go

@@ -15,10 +15,9 @@ package collectors
 
 import (
 	"database/sql"
-	"runtime"
 	"testing"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 func TestDBStatsCollector(t *testing.T) {
@@ -50,9 +49,7 @@ func TestDBStatsCollector(t *testing.T) {
 		"go_sql_wait_duration_seconds_total",
 		"go_sql_max_idle_closed_total",
 		"go_sql_max_lifetime_closed_total",
-	}
+		"go_sql_max_idle_time_closed_total",
-	if runtime.Version() >= "go1.15" {
-		names = append(names, "go_sql_max_idle_time_closed_total")
 	}
 	type result struct {
 		found bool

prometheus/collectors/expvar_collector.go

@@ -13,7 +13,7 @@
 
 package collectors
 
-import "github.com/prometheus/client_golang/prometheus"
+import "git.internal/re/client_golang/prometheus"
 
 // NewExpvarCollector returns a newly allocated expvar Collector.
 //

prometheus/collectors/go_collector_go116.go

@@ -16,7 +16,7 @@
 
 package collectors
 
-import "github.com/prometheus/client_golang/prometheus"
+import "git.internal/re/client_golang/prometheus"
 
 // NewGoCollector returns a collector that exports metrics about the current Go
 // process. This includes memory stats. To collect those, runtime.ReadMemStats

prometheus/collectors/go_collector_go117_test.go

@@ -0,0 +1,100 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.17 && !go1.19
+// +build go1.17,!go1.19
+
+package collectors
+
+func withAllMetrics() []string {
+	return withBaseMetrics([]string{
+		"go_gc_cycles_automatic_gc_cycles_total",
+		"go_gc_cycles_forced_gc_cycles_total",
+		"go_gc_cycles_total_gc_cycles_total",
+		"go_gc_heap_allocs_by_size_bytes",
+		"go_gc_heap_allocs_bytes_total",
+		"go_gc_heap_allocs_objects_total",
+		"go_gc_heap_frees_by_size_bytes",
+		"go_gc_heap_frees_bytes_total",
+		"go_gc_heap_frees_objects_total",
+		"go_gc_heap_goal_bytes",
+		"go_gc_heap_objects_objects",
+		"go_gc_heap_tiny_allocs_objects_total",
+		"go_gc_pauses_seconds",
+		"go_memory_classes_heap_free_bytes",
+		"go_memory_classes_heap_objects_bytes",
+		"go_memory_classes_heap_released_bytes",
+		"go_memory_classes_heap_stacks_bytes",
+		"go_memory_classes_heap_unused_bytes",
+		"go_memory_classes_metadata_mcache_free_bytes",
+		"go_memory_classes_metadata_mcache_inuse_bytes",
+		"go_memory_classes_metadata_mspan_free_bytes",
+		"go_memory_classes_metadata_mspan_inuse_bytes",
+		"go_memory_classes_metadata_other_bytes",
+		"go_memory_classes_os_stacks_bytes",
+		"go_memory_classes_other_bytes",
+		"go_memory_classes_profiling_buckets_bytes",
+		"go_memory_classes_total_bytes",
+		"go_sched_goroutines_goroutines",
+		"go_sched_latencies_seconds",
+	})
+}
+
+func withGCMetrics() []string {
+	return withBaseMetrics([]string{
+		"go_gc_cycles_automatic_gc_cycles_total",
+		"go_gc_cycles_forced_gc_cycles_total",
+		"go_gc_cycles_total_gc_cycles_total",
+		"go_gc_heap_allocs_by_size_bytes",
+		"go_gc_heap_allocs_bytes_total",
+		"go_gc_heap_allocs_objects_total",
+		"go_gc_heap_frees_by_size_bytes",
+		"go_gc_heap_frees_bytes_total",
+		"go_gc_heap_frees_objects_total",
+		"go_gc_heap_goal_bytes",
+		"go_gc_heap_objects_objects",
+		"go_gc_heap_tiny_allocs_objects_total",
+		"go_gc_pauses_seconds",
+	})
+}
+
+func withMemoryMetrics() []string {
+	return withBaseMetrics([]string{
+		"go_memory_classes_heap_free_bytes",
+		"go_memory_classes_heap_objects_bytes",
+		"go_memory_classes_heap_released_bytes",
+		"go_memory_classes_heap_stacks_bytes",
+		"go_memory_classes_heap_unused_bytes",
+		"go_memory_classes_metadata_mcache_free_bytes",
+		"go_memory_classes_metadata_mcache_inuse_bytes",
+		"go_memory_classes_metadata_mspan_free_bytes",
+		"go_memory_classes_metadata_mspan_inuse_bytes",
+		"go_memory_classes_metadata_other_bytes",
+		"go_memory_classes_os_stacks_bytes",
+		"go_memory_classes_other_bytes",
+		"go_memory_classes_profiling_buckets_bytes",
+		"go_memory_classes_total_bytes",
+	})
+}
+
+func withSchedulerMetrics() []string {
+	return []string{
+		"go_gc_duration_seconds",
+		"go_goroutines",
+		"go_info",
+		"go_memstats_last_gc_time_seconds",
+		"go_sched_goroutines_goroutines",
+		"go_sched_latencies_seconds",
+		"go_threads",
+	}
+}

prometheus/collectors/go_collector_go119_test.go

@@ -0,0 +1,107 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.19 && !go1.20
+// +build go1.19,!go1.20
+
+package collectors
+
+func withAllMetrics() []string {
+	return withBaseMetrics([]string{
+		"go_cgo_go_to_c_calls_calls_total",
+		"go_gc_cycles_automatic_gc_cycles_total",
+		"go_gc_cycles_forced_gc_cycles_total",
+		"go_gc_cycles_total_gc_cycles_total",
+		"go_gc_heap_allocs_by_size_bytes",
+		"go_gc_heap_allocs_bytes_total",
+		"go_gc_heap_allocs_objects_total",
+		"go_gc_heap_frees_by_size_bytes",
+		"go_gc_heap_frees_bytes_total",
+		"go_gc_heap_frees_objects_total",
+		"go_gc_heap_goal_bytes",
+		"go_gc_heap_objects_objects",
+		"go_gc_heap_tiny_allocs_objects_total",
+		"go_gc_limiter_last_enabled_gc_cycle",
+		"go_gc_pauses_seconds",
+		"go_gc_stack_starting_size_bytes",
+		"go_memory_classes_heap_free_bytes",
+		"go_memory_classes_heap_objects_bytes",
+		"go_memory_classes_heap_released_bytes",
+		"go_memory_classes_heap_stacks_bytes",
+		"go_memory_classes_heap_unused_bytes",
+		"go_memory_classes_metadata_mcache_free_bytes",
+		"go_memory_classes_metadata_mcache_inuse_bytes",
+		"go_memory_classes_metadata_mspan_free_bytes",
+		"go_memory_classes_metadata_mspan_inuse_bytes",
+		"go_memory_classes_metadata_other_bytes",
+		"go_memory_classes_os_stacks_bytes",
+		"go_memory_classes_other_bytes",
+		"go_memory_classes_profiling_buckets_bytes",
+		"go_memory_classes_total_bytes",
+		"go_sched_gomaxprocs_threads",
+		"go_sched_goroutines_goroutines",
+		"go_sched_latencies_seconds",
+	})
+}
+
+func withGCMetrics() []string {
+	return withBaseMetrics([]string{
+		"go_gc_cycles_automatic_gc_cycles_total",
+		"go_gc_cycles_forced_gc_cycles_total",
+		"go_gc_cycles_total_gc_cycles_total",
+		"go_gc_heap_allocs_by_size_bytes",
+		"go_gc_heap_allocs_bytes_total",
+		"go_gc_heap_allocs_objects_total",
+		"go_gc_heap_frees_by_size_bytes",
+		"go_gc_heap_frees_bytes_total",
+		"go_gc_heap_frees_objects_total",
+		"go_gc_heap_goal_bytes",
+		"go_gc_heap_objects_objects",
+		"go_gc_heap_tiny_allocs_objects_total",
+		"go_gc_limiter_last_enabled_gc_cycle",
+		"go_gc_pauses_seconds",
+		"go_gc_stack_starting_size_bytes",
+	})
+}
+
+func withMemoryMetrics() []string {
+	return withBaseMetrics([]string{
+		"go_memory_classes_heap_free_bytes",
+		"go_memory_classes_heap_objects_bytes",
+		"go_memory_classes_heap_released_bytes",
+		"go_memory_classes_heap_stacks_bytes",
+		"go_memory_classes_heap_unused_bytes",
+		"go_memory_classes_metadata_mcache_free_bytes",
+		"go_memory_classes_metadata_mcache_inuse_bytes",
+		"go_memory_classes_metadata_mspan_free_bytes",
+		"go_memory_classes_metadata_mspan_inuse_bytes",
+		"go_memory_classes_metadata_other_bytes",
+		"go_memory_classes_os_stacks_bytes",
+		"go_memory_classes_other_bytes",
+		"go_memory_classes_profiling_buckets_bytes",
+		"go_memory_classes_total_bytes",
+	})
+}
+
+func withSchedulerMetrics() []string {
+	return []string{
+		"go_gc_duration_seconds",
+		"go_goroutines",
+		"go_info",
+		"go_memstats_last_gc_time_seconds",
+		"go_sched_gomaxprocs_threads",
+		"go_sched_goroutines_goroutines",
+		"go_sched_latencies_seconds",
+		"go_threads",
+	}
+}

prometheus/collectors/go_collector_latest.go

@@ -16,76 +16,145 @@
 
 package collectors
 
-import "github.com/prometheus/client_golang/prometheus"
+import (
+	"regexp"
 
-//nolint:staticcheck // Ignore SA1019 until v2.
+	"git.internal/re/client_golang/prometheus"
-type goOptions = prometheus.GoCollectorOptions
+	"git.internal/re/client_golang/prometheus/internal"
-type goOption func(o *goOptions)
+)
 
+var (
+	// MetricsAll allows all the metrics to be collected from Go runtime.
+	MetricsAll = GoRuntimeMetricsRule{regexp.MustCompile("/.*")}
+	// MetricsGC allows only GC metrics to be collected from Go runtime.
+	// e.g. go_gc_cycles_automatic_gc_cycles_total
+	MetricsGC = GoRuntimeMetricsRule{regexp.MustCompile(`^/gc/.*`)}
+	// MetricsMemory allows only memory metrics to be collected from Go runtime.
+	// e.g. go_memory_classes_heap_free_bytes
+	MetricsMemory = GoRuntimeMetricsRule{regexp.MustCompile(`^/memory/.*`)}
+	// MetricsScheduler allows only scheduler metrics to be collected from Go runtime.
+	// e.g. go_sched_goroutines_goroutines
+	MetricsScheduler = GoRuntimeMetricsRule{regexp.MustCompile(`^/sched/.*`)}
+)
+
+// WithGoCollectorMemStatsMetricsDisabled disables metrics that is gathered in runtime.MemStats structure such as:
+//
+// go_memstats_alloc_bytes
+// go_memstats_alloc_bytes_total
+// go_memstats_sys_bytes
+// go_memstats_lookups_total
+// go_memstats_mallocs_total
+// go_memstats_frees_total
+// go_memstats_heap_alloc_bytes
+// go_memstats_heap_sys_bytes
+// go_memstats_heap_idle_bytes
+// go_memstats_heap_inuse_bytes
+// go_memstats_heap_released_bytes
+// go_memstats_heap_objects
+// go_memstats_stack_inuse_bytes
+// go_memstats_stack_sys_bytes
+// go_memstats_mspan_inuse_bytes
+// go_memstats_mspan_sys_bytes
+// go_memstats_mcache_inuse_bytes
+// go_memstats_mcache_sys_bytes
+// go_memstats_buck_hash_sys_bytes
+// go_memstats_gc_sys_bytes
+// go_memstats_other_sys_bytes
+// go_memstats_next_gc_bytes
+//
+// so the metrics known from pre client_golang v1.12.0,
+//
+// NOTE(bwplotka): The above represents runtime.MemStats statistics, but they are
+// actually implemented using new runtime/metrics package. (except skipped go_memstats_gc_cpu_fraction
+// -- see  https://git.internal/re/client_golang/issues/842#issuecomment-861812034 for explanation).
+//
+// Some users might want to disable this on collector level (although you can use scrape relabelling on Prometheus),
+// because similar metrics can be now obtained using WithGoCollectorRuntimeMetrics. Note that the semantics of new
+// metrics might be different, plus the names can be change over time with different Go version.
+//
+// NOTE(bwplotka): Changing metric names can be tedious at times as the alerts, recording rules and dashboards have to be adjusted.
+// The old metrics are also very useful, with many guides and books written about how to interpret them.
+//
+// As a result our recommendation would be to stick with MemStats like metrics and enable other runtime/metrics if you are interested
+// in advanced insights Go provides. See ExampleGoCollector_WithAdvancedGoMetrics.
+func WithGoCollectorMemStatsMetricsDisabled() func(options *internal.GoCollectorOptions) {
+	return func(o *internal.GoCollectorOptions) {
+		o.DisableMemStatsLikeMetrics = true
+	}
+}
+
+// GoRuntimeMetricsRule allow enabling and configuring particular group of runtime/metrics.
+// TODO(bwplotka): Consider adding ability to adjust buckets.
+type GoRuntimeMetricsRule struct {
+	// Matcher represents RE2 expression will match the runtime/metrics from https://golang.bg/src/runtime/metrics/description.go
+	// Use `regexp.MustCompile` or `regexp.Compile` to create this field.
+	Matcher *regexp.Regexp
+}
+
+// WithGoCollectorRuntimeMetrics allows enabling and configuring particular group of runtime/metrics.
+// See the list of metrics https://golang.bg/src/runtime/metrics/description.go (pick the Go version you use there!).
+// You can use this option in repeated manner, which will add new rules. The order of rules is important, the last rule
+// that matches particular metrics is applied.
+func WithGoCollectorRuntimeMetrics(rules ...GoRuntimeMetricsRule) func(options *internal.GoCollectorOptions) {
+	rs := make([]internal.GoCollectorRule, len(rules))
+	for i, r := range rules {
+		rs[i] = internal.GoCollectorRule{
+			Matcher: r.Matcher,
+		}
+	}
+
+	return func(o *internal.GoCollectorOptions) {
+		o.RuntimeMetricRules = append(o.RuntimeMetricRules, rs...)
+	}
+}
+
+// WithoutGoCollectorRuntimeMetrics allows disabling group of runtime/metrics that you might have added in WithGoCollectorRuntimeMetrics.
+// It behaves similarly to WithGoCollectorRuntimeMetrics just with deny-list semantics.
+func WithoutGoCollectorRuntimeMetrics(matchers ...*regexp.Regexp) func(options *internal.GoCollectorOptions) {
+	rs := make([]internal.GoCollectorRule, len(matchers))
+	for i, m := range matchers {
+		rs[i] = internal.GoCollectorRule{
+			Matcher: m,
+			Deny:    true,
+		}
+	}
+
+	return func(o *internal.GoCollectorOptions) {
+		o.RuntimeMetricRules = append(o.RuntimeMetricRules, rs...)
+	}
+}
+
+// GoCollectionOption represents Go collection option flag.
+// Deprecated.
 type GoCollectionOption uint32
 
 const (
-	// GoRuntimeMemStatsCollection represents the metrics represented by runtime.MemStats structure such as
+	// GoRuntimeMemStatsCollection represents the metrics represented by runtime.MemStats structure.
-	// go_memstats_alloc_bytes
+	// Deprecated. Use WithGoCollectorMemStatsMetricsDisabled() function to disable those metrics in the collector.
-	// go_memstats_alloc_bytes_total
-	// go_memstats_sys_bytes
-	// go_memstats_lookups_total
-	// go_memstats_mallocs_total
-	// go_memstats_frees_total
-	// go_memstats_heap_alloc_bytes
-	// go_memstats_heap_sys_bytes
-	// go_memstats_heap_idle_bytes
-	// go_memstats_heap_inuse_bytes
-	// go_memstats_heap_released_bytes
-	// go_memstats_heap_objects
-	// go_memstats_stack_inuse_bytes
-	// go_memstats_stack_sys_bytes
-	// go_memstats_mspan_inuse_bytes
-	// go_memstats_mspan_sys_bytes
-	// go_memstats_mcache_inuse_bytes
-	// go_memstats_mcache_sys_bytes
-	// go_memstats_buck_hash_sys_bytes
-	// go_memstats_gc_sys_bytes
-	// go_memstats_other_sys_bytes
-	// go_memstats_next_gc_bytes
-	// so the metrics known from pre client_golang v1.12.0, except skipped go_memstats_gc_cpu_fraction (see
-	// https://github.com/prometheus/client_golang/issues/842#issuecomment-861812034 for explanation.
-	//
-	// NOTE that this mode represents runtime.MemStats statistics, but they are
-	// actually implemented using new runtime/metrics package.
-	// Deprecated: Use GoRuntimeMetricsCollection instead going forward.
 	GoRuntimeMemStatsCollection GoCollectionOption = 1 << iota
-	// GoRuntimeMetricsCollection is the new set of metrics represented by runtime/metrics package and follows
+	// GoRuntimeMetricsCollection is the new set of metrics represented by runtime/metrics package.
-	// consistent naming. The exposed metric set depends on Go version, but it is controlled against
+	// Deprecated. Use WithGoCollectorRuntimeMetrics(GoRuntimeMetricsRule{Matcher: regexp.MustCompile("/.*")})
-	// unexpected cardinality. This set has overlapping information with GoRuntimeMemStatsCollection, just with
+	// function to enable those metrics in the collector.
-	// new names. GoRuntimeMetricsCollection is what is recommended for using going forward.
 	GoRuntimeMetricsCollection
 )
 
-// WithGoCollections allows enabling different collections for Go collector on top of base metrics
+// WithGoCollections allows enabling different collections for Go collector on top of base metrics.
-// like go_goroutines, go_threads, go_gc_duration_seconds, go_memstats_last_gc_time_seconds, go_info.
+// Deprecated. Use WithGoCollectorRuntimeMetrics() and WithGoCollectorMemStatsMetricsDisabled() instead to control metrics.
-//
+func WithGoCollections(flags GoCollectionOption) func(options *internal.GoCollectorOptions) {
-// Check GoRuntimeMemStatsCollection and GoRuntimeMetricsCollection for more details. You can use none,
+	return func(options *internal.GoCollectorOptions) {
-// one or more collections at once. For example:
+		if flags&GoRuntimeMemStatsCollection == 0 {
-// WithGoCollections(GoRuntimeMemStatsCollection | GoRuntimeMetricsCollection) means both GoRuntimeMemStatsCollection
+			WithGoCollectorMemStatsMetricsDisabled()(options)
-// metrics and GoRuntimeMetricsCollection will be exposed.
+		}
-//
+
-// The current default is GoRuntimeMemStatsCollection, so the compatibility mode with
+		if flags&GoRuntimeMetricsCollection != 0 {
-// client_golang pre v1.12 (move to runtime/metrics).
+			WithGoCollectorRuntimeMetrics(GoRuntimeMetricsRule{Matcher: regexp.MustCompile("/.*")})(options)
-func WithGoCollections(flags GoCollectionOption) goOption {
+		}
-	return func(o *goOptions) {
-		o.EnabledCollections = uint32(flags)
 	}
 }
 
 // NewGoCollector returns a collector that exports metrics about the current Go
-// process using debug.GCStats using runtime/metrics.
+// process using debug.GCStats (base metrics) and runtime/metrics (both in MemStats style and new ones).
-func NewGoCollector(opts ...goOption) prometheus.Collector {
+func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) prometheus.Collector {
 	//nolint:staticcheck // Ignore SA1019 until v2.
-	promPkgOpts := make([]func(o *prometheus.GoCollectorOptions), len(opts))
+	return prometheus.NewGoCollector(opts...)
-	for i, opt := range opts {
-		promPkgOpts[i] = opt
-	}
-	//nolint:staticcheck // Ignore SA1019 until v2.
-	return prometheus.NewGoCollector(promPkgOpts...)
 }

prometheus/collectors/go_collector_latest_test.go

@@ -18,15 +18,31 @@ package collectors
 
 import (
 	"encoding/json"
+	"log"
+	"net/http"
+	"reflect"
+	"regexp"
+	"sort"
 	"testing"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus/promhttp"
 )
 
+var baseMetrics = []string{
+	"go_gc_duration_seconds",
+	"go_goroutines",
+	"go_info",
+	"go_memstats_last_gc_time_seconds",
+	"go_threads",
+}
+
 func TestGoCollectorMarshalling(t *testing.T) {
 	reg := prometheus.NewRegistry()
 	reg.MustRegister(NewGoCollector(
-		WithGoCollections(GoRuntimeMemStatsCollection | GoRuntimeMetricsCollection),
+		WithGoCollectorRuntimeMetrics(GoRuntimeMetricsRule{
+			Matcher: regexp.MustCompile("/.*"),
+		}),
 	))
 	result, err := reg.Gather()
 	if err != nil {
@@ -37,3 +53,181 @@ func TestGoCollectorMarshalling(t *testing.T) {
 		t.Errorf("json marshalling shoud not fail, %v", err)
 	}
 }
+
+func TestWithGoCollectorMemStatsMetricsDisabled(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(NewGoCollector(
+		WithGoCollectorMemStatsMetricsDisabled(),
+	))
+	result, err := reg.Gather()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	got := []string{}
+	for _, r := range result {
+		got = append(got, r.GetName())
+	}
+
+	if !reflect.DeepEqual(got, baseMetrics) {
+		t.Errorf("got %v, want %v", got, baseMetrics)
+	}
+}
+
+func TestGoCollectorAllowList(t *testing.T) {
+	for _, test := range []struct {
+		name     string
+		rules    []GoRuntimeMetricsRule
+		expected []string
+	}{
+		{
+			name:     "Without any rules",
+			rules:    nil,
+			expected: baseMetrics,
+		},
+		{
+			name:     "allow all",
+			rules:    []GoRuntimeMetricsRule{MetricsAll},
+			expected: withAllMetrics(),
+		},
+		{
+			name:     "allow GC",
+			rules:    []GoRuntimeMetricsRule{MetricsGC},
+			expected: withGCMetrics(),
+		},
+		{
+			name:     "allow Memory",
+			rules:    []GoRuntimeMetricsRule{MetricsMemory},
+			expected: withMemoryMetrics(),
+		},
+		{
+			name:     "allow Scheduler",
+			rules:    []GoRuntimeMetricsRule{MetricsScheduler},
+			expected: withSchedulerMetrics(),
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			reg := prometheus.NewRegistry()
+			reg.MustRegister(NewGoCollector(
+				WithGoCollectorMemStatsMetricsDisabled(),
+				WithGoCollectorRuntimeMetrics(test.rules...),
+			))
+			result, err := reg.Gather()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			got := []string{}
+			for _, r := range result {
+				got = append(got, r.GetName())
+			}
+
+			if !reflect.DeepEqual(got, test.expected) {
+				t.Errorf("got %v, want %v", got, test.expected)
+			}
+		})
+	}
+}
+
+func withBaseMetrics(metricNames []string) []string {
+	metricNames = append(metricNames, baseMetrics...)
+	sort.Strings(metricNames)
+	return metricNames
+}
+
+func TestGoCollectorDenyList(t *testing.T) {
+	for _, test := range []struct {
+		name     string
+		matchers []*regexp.Regexp
+		expected []string
+	}{
+		{
+			name:     "Without any matchers",
+			matchers: nil,
+			expected: baseMetrics,
+		},
+		{
+			name:     "deny all",
+			matchers: []*regexp.Regexp{regexp.MustCompile("/.*")},
+			expected: baseMetrics,
+		},
+		{
+			name: "deny gc and scheduler latency",
+			matchers: []*regexp.Regexp{
+				regexp.MustCompile("^/gc/.*"),
+				regexp.MustCompile("^/sched/latencies:.*"),
+			},
+			expected: baseMetrics,
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			reg := prometheus.NewRegistry()
+			reg.MustRegister(NewGoCollector(
+				WithGoCollectorMemStatsMetricsDisabled(),
+				WithoutGoCollectorRuntimeMetrics(test.matchers...),
+			))
+			result, err := reg.Gather()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			got := []string{}
+			for _, r := range result {
+				got = append(got, r.GetName())
+			}
+
+			if !reflect.DeepEqual(got, test.expected) {
+				t.Errorf("got %v, want %v", got, test.expected)
+			}
+		})
+	}
+}
+
+func ExampleGoCollector() {
+	reg := prometheus.NewRegistry()
+
+	// Register the GoCollector with the default options. Only the base metrics will be enabled.
+	reg.MustRegister(NewGoCollector())
+
+	http.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{}))
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}
+
+func ExampleGoCollector_WithAdvancedGoMetrics() {
+	reg := prometheus.NewRegistry()
+
+	// Enable Go metrics with pre-defined rules. Or your custom rules.
+	reg.MustRegister(
+		NewGoCollector(
+			WithGoCollectorMemStatsMetricsDisabled(),
+			WithGoCollectorRuntimeMetrics(
+				MetricsScheduler,
+				MetricsMemory,
+				GoRuntimeMetricsRule{
+					Matcher: regexp.MustCompile("^/mycustomrule.*"),
+				},
+			),
+			WithoutGoCollectorRuntimeMetrics(regexp.MustCompile("^/gc/.*")),
+		))
+
+	http.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{}))
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}
+
+func ExampleGoCollector_DefaultRegister() {
+	// Unregister the default GoCollector.
+	prometheus.Unregister(NewGoCollector())
+
+	// Register the default GoCollector with a custom config.
+	prometheus.MustRegister(NewGoCollector(WithGoCollectorRuntimeMetrics(
+		MetricsScheduler,
+		MetricsGC,
+		GoRuntimeMetricsRule{
+			Matcher: regexp.MustCompile("^/mycustomrule.*"),
+		},
+	),
+	))
+
+	http.Handle("/metrics", promhttp.Handler())
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}

prometheus/collectors/process_collector.go

@@ -13,7 +13,7 @@
 
 package collectors
 
-import "github.com/prometheus/client_golang/prometheus"
+import "git.internal/re/client_golang/prometheus"
 
 // ProcessCollectorOpts defines the behavior of a process metrics collector
 // created with NewProcessCollector.

prometheus/counter.go

@@ -51,7 +51,7 @@ type Counter interface {
 // will lead to a valid (label-less) exemplar. But if Labels is nil, the current
 // exemplar is left in place. AddWithExemplar panics if the value is < 0, if any
 // of the provided labels are invalid, or if the provided labels contain more
-// than 64 runes in total.
+// than 128 runes in total.
 type ExemplarAdder interface {
 	AddWithExemplar(value float64, exemplar Labels)
 }
@@ -140,12 +140,13 @@ func (c *counter) get() float64 {
 }
 
 func (c *counter) Write(out *dto.Metric) error {
-	val := c.get()
+	// Read the Exemplar first and the value second. This is to avoid a race condition
-
+	// where users see an exemplar for a not-yet-existing observation.
 	var exemplar *dto.Exemplar
 	if e := c.exemplar.Load(); e != nil {
 		exemplar = e.(*dto.Exemplar)
 	}
+	val := c.get()
 
 	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out)
 }
@@ -245,7 +246,8 @@ func (v *CounterVec) GetMetricWith(labels Labels) (Counter, error) {
 // WithLabelValues works as GetMetricWithLabelValues, but panics where
 // GetMetricWithLabelValues would have returned an error. Not returning an
 // error allows shortcuts like
-//     myVec.WithLabelValues("404", "GET").Add(42)
+//
+//	myVec.WithLabelValues("404", "GET").Add(42)
 func (v *CounterVec) WithLabelValues(lvs ...string) Counter {
 	c, err := v.GetMetricWithLabelValues(lvs...)
 	if err != nil {
@@ -256,7 +258,8 @@ func (v *CounterVec) WithLabelValues(lvs ...string) Counter {
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. Not returning an error allows shortcuts like
-//     myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Add(42)
+//
+//	myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Add(42)
 func (v *CounterVec) With(labels Labels) Counter {
 	c, err := v.GetMetricWith(labels)
 	if err != nil {

prometheus/counter_test.go

@@ -16,6 +16,7 @@ package prometheus
 import (
 	"fmt"
 	"math"
+	"strings"
 	"testing"
 	"time"
 
@@ -231,7 +232,7 @@ func TestCounterExemplar(t *testing.T) {
 	}
 	expectedExemplar := &dto.Exemplar{
 		Label: []*dto.LabelPair{
-			&dto.LabelPair{Name: proto.String("foo"), Value: proto.String("bar")},
+			{Name: proto.String("foo"), Value: proto.String("bar")},
 		},
 		Value:     proto.Float64(42),
 		Timestamp: ts,
@@ -262,10 +263,11 @@ func TestCounterExemplar(t *testing.T) {
 				err = e.(error)
 			}
 		}()
-		// Should panic because of 65 runes.
+		// Should panic because of 129 runes.
 		counter.AddWithExemplar(42, Labels{
 			"abcdefghijklmnopqrstuvwxyz": "26+16 characters",
 			"x1234567":                   "8+15 characters",
+			"z":                          strings.Repeat("x", 63),
 		})
 		return nil
 	}

prometheus/desc.go

@@ -20,6 +20,9 @@ import (
 	"strings"
 
 	"github.com/cespare/xxhash/v2"
+
+	"git.internal/re/client_golang/prometheus/internal"
+
 	//nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility.
 	"github.com/golang/protobuf/proto"
 	"github.com/prometheus/common/model"
@@ -154,7 +157,7 @@ func NewDesc(fqName, help string, variableLabels []string, constLabels Labels) *
 			Value: proto.String(v),
 		})
 	}
-	sort.Sort(labelPairSorter(d.constLabelPairs))
+	sort.Sort(internal.LabelPairSorter(d.constLabelPairs))
 	return d
 }
 

prometheus/doc.go

@@ -21,55 +21,66 @@
 // All exported functions and methods are safe to be used concurrently unless
 // specified otherwise.
 //
-// A Basic Example
+// # A Basic Example
 //
 // As a starting point, a very basic usage example:
 //
-//    package main
+//	package main
 //
-//    import (
+//	import (
-//    	"log"
+//		"log"
-//    	"net/http"
+//		"net/http"
 //
-//    	"github.com/prometheus/client_golang/prometheus"
+//		"git.internal/re/client_golang/prometheus"
-//    	"github.com/prometheus/client_golang/prometheus/promhttp"
+//		"git.internal/re/client_golang/prometheus/promhttp"
-//    )
+//	)
 //
-//    var (
+//	type metrics struct {
-//    	cpuTemp = prometheus.NewGauge(prometheus.GaugeOpts{
+//		cpuTemp  prometheus.Gauge
-//    		Name: "cpu_temperature_celsius",
+//	  hdFailures *prometheus.CounterVec
-//    		Help: "Current temperature of the CPU.",
+//	}
-//    	})
-//    	hdFailures = prometheus.NewCounterVec(
-//    		prometheus.CounterOpts{
-//    			Name: "hd_errors_total",
-//    			Help: "Number of hard-disk errors.",
-//    		},
-//    		[]string{"device"},
-//    	)
-//    )
 //
-//    func init() {
+//	func NewMetrics(reg prometheus.Registerer) *metrics {
-//    	// Metrics have to be registered to be exposed:
+//	  m := &metrics{
-//    	prometheus.MustRegister(cpuTemp)
+//	    cpuTemp: prometheus.NewGauge(prometheus.GaugeOpts{
-//    	prometheus.MustRegister(hdFailures)
+//	      Name: "cpu_temperature_celsius",
-//    }
+//	      Help: "Current temperature of the CPU.",
+//	    }),
+//	    hdFailures: prometheus.NewCounterVec(
+//	      prometheus.CounterOpts{
+//	        Name: "hd_errors_total",
+//	        Help: "Number of hard-disk errors.",
+//	      },
+//	      []string{"device"},
+//	    ),
+//	  }
+//	  reg.MustRegister(m.cpuTemp)
+//	  reg.MustRegister(m.hdFailures)
+//	  return m
+//	}
 //
-//    func main() {
+//	func main() {
-//    	cpuTemp.Set(65.3)
+//	  // Create a non-global registry.
-//    	hdFailures.With(prometheus.Labels{"device":"/dev/sda"}).Inc()
+//	  reg := prometheus.NewRegistry()
 //
-//    	// The Handler function provides a default handler to expose metrics
+//	  // Create new metrics and register them using the custom registry.
-//    	// via an HTTP server. "/metrics" is the usual endpoint for that.
+//	  m := NewMetrics(reg)
-//    	http.Handle("/metrics", promhttp.Handler())
+//	  // Set values for the new created metrics.
-//    	log.Fatal(http.ListenAndServe(":8080", nil))
+//		m.cpuTemp.Set(65.3)
-//    }
+//		m.hdFailures.With(prometheus.Labels{"device":"/dev/sda"}).Inc()
 //
+//		// Expose metrics and custom registry via an HTTP server
+//		// using the HandleFor function. "/metrics" is the usual endpoint for that.
+//		http.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{Registry: reg}))
+//		log.Fatal(http.ListenAndServe(":8080", nil))
+//	}
 //
 // This is a complete program that exports two metrics, a Gauge and a Counter,
 // the latter with a label attached to turn it into a (one-dimensional) vector.
+// It register the metrics using a custom registry and exposes them via an HTTP server
+// on the /metrics endpoint.
 //
-// Metrics
+// # Metrics
 //
 // The number of exported identifiers in this package might appear a bit
 // overwhelming. However, in addition to the basic plumbing shown in the example
@@ -100,7 +111,7 @@
 // To create instances of Metrics and their vector versions, you need a suitable
 // …Opts struct, i.e. GaugeOpts, CounterOpts, SummaryOpts, or HistogramOpts.
 //
-// Custom Collectors and constant Metrics
+// # Custom Collectors and constant Metrics
 //
 // While you could create your own implementations of Metric, most likely you
 // will only ever implement the Collector interface on your own. At a first
@@ -141,7 +152,7 @@
 // a metric, GaugeFunc, CounterFunc, or UntypedFunc might be interesting
 // shortcuts.
 //
-// Advanced Uses of the Registry
+// # Advanced Uses of the Registry
 //
 // While MustRegister is the by far most common way of registering a Collector,
 // sometimes you might want to handle the errors the registration might cause.
@@ -176,23 +187,23 @@
 // NewProcessCollector). With a custom registry, you are in control and decide
 // yourself about the Collectors to register.
 //
-// HTTP Exposition
+// # HTTP Exposition
 //
 // The Registry implements the Gatherer interface. The caller of the Gather
 // method can then expose the gathered metrics in some way. Usually, the metrics
 // are served via HTTP on the /metrics endpoint. That's happening in the example
 // above. The tools to expose metrics via HTTP are in the promhttp sub-package.
 //
-// Pushing to the Pushgateway
+// # Pushing to the Pushgateway
 //
 // Function for pushing to the Pushgateway can be found in the push sub-package.
 //
-// Graphite Bridge
+// # Graphite Bridge
 //
 // Functions and examples to push metrics from a Gatherer to Graphite can be
 // found in the graphite sub-package.
 //
-// Other Means of Exposition
+// # Other Means of Exposition
 //
 // More ways of exposing metrics can easily be added by following the approaches
 // of the existing implementations.

prometheus/example_clustermanager_test.go

@@ -17,8 +17,8 @@ import (
 	"log"
 	"net/http"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"git.internal/re/client_golang/prometheus/promhttp"
 )
 
 // ClusterManager is an example for a system that might have been built without

prometheus/example_metricvec_test.go

@@ -21,7 +21,7 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 // Info implements an info pseudo-metric, which is modeled as a Gauge that
@@ -108,7 +108,6 @@ func (v *InfoVec) MustCurryWith(labels prometheus.Labels) *InfoVec {
 }
 
 func ExampleMetricVec() {
-
 	infoVec := NewInfoVec(
 		"library_version_info",
 		"Versions of the libraries used in this binary.",

prometheus/example_timer_complex_test.go

@@ -16,30 +16,28 @@ package prometheus_test
 import (
 	"net/http"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
-var (
+// apiRequestDuration tracks the duration separate for each HTTP status
-	// apiRequestDuration tracks the duration separate for each HTTP status
+// class (1xx, 2xx, ...). This creates a fair amount of time series on
-	// class (1xx, 2xx, ...). This creates a fair amount of time series on
+// the Prometheus server. Usually, you would track the duration of
-	// the Prometheus server. Usually, you would track the duration of
+// serving HTTP request without partitioning by outcome. Do something
-	// serving HTTP request without partitioning by outcome. Do something
+// like this only if needed. Also note how only status classes are
-	// like this only if needed. Also note how only status classes are
+// tracked, not every single status code. The latter would create an
-	// tracked, not every single status code. The latter would create an
+// even larger amount of time series. Request counters partitioned by
-	// even larger amount of time series. Request counters partitioned by
+// status code are usually OK as each counter only creates one time
-	// status code are usually OK as each counter only creates one time
+// series. Histograms are way more expensive, so partition with care and
-	// series. Histograms are way more expensive, so partition with care and
+// only where you really need separate latency tracking. Partitioning by
-	// only where you really need separate latency tracking. Partitioning by
+// status class is only an example. In concrete cases, other partitions
-	// status class is only an example. In concrete cases, other partitions
+// might make more sense.
-	// might make more sense.
+var apiRequestDuration = prometheus.NewHistogramVec(
-	apiRequestDuration = prometheus.NewHistogramVec(
+	prometheus.HistogramOpts{
-		prometheus.HistogramOpts{
+		Name:    "api_request_duration_seconds",
-			Name:    "api_request_duration_seconds",
+		Help:    "Histogram for the request duration of the public API, partitioned by status class.",
-			Help:    "Histogram for the request duration of the public API, partitioned by status class.",
+		Buckets: prometheus.ExponentialBuckets(0.1, 1.5, 5),
-			Buckets: prometheus.ExponentialBuckets(0.1, 1.5, 5),
+	},
-		},
+	[]string{"status_class"},
-		[]string{"status_class"},
-	)
 )
 
 func handler(w http.ResponseWriter, r *http.Request) {

prometheus/example_timer_gauge_test.go

@@ -16,20 +16,18 @@ package prometheus_test
 import (
 	"os"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
-var (
+// If a function is called rarely (i.e. not more often than scrapes
-	// If a function is called rarely (i.e. not more often than scrapes
+// happen) or ideally only once (like in a batch job), it can make sense
-	// happen) or ideally only once (like in a batch job), it can make sense
+// to use a Gauge for timing the function call. For timing a batch job
-	// to use a Gauge for timing the function call. For timing a batch job
+// and pushing the result to a Pushgateway, see also the comprehensive
-	// and pushing the result to a Pushgateway, see also the comprehensive
+// example in the push package.
-	// example in the push package.
+var funcDuration = prometheus.NewGauge(prometheus.GaugeOpts{
-	funcDuration = prometheus.NewGauge(prometheus.GaugeOpts{
+	Name: "example_function_duration_seconds",
-		Name: "example_function_duration_seconds",
+	Help: "Duration of the last call of an example function.",
-		Help: "Duration of the last call of an example function.",
+})
-	})
-)
 
 func run() error {
 	// The Set method of the Gauge is used to observe the duration.

prometheus/example_timer_test.go

@@ -17,16 +17,14 @@ import (
 	"math/rand"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
-var (
+var requestDuration = prometheus.NewHistogram(prometheus.HistogramOpts{
-	requestDuration = prometheus.NewHistogram(prometheus.HistogramOpts{
+	Name:    "example_request_duration_seconds",
-		Name:    "example_request_duration_seconds",
+	Help:    "Histogram for the runtime of a simple example function.",
-		Help:    "Histogram for the runtime of a simple example function.",
+	Buckets: prometheus.LinearBuckets(0.01, 0.01, 10),
-		Buckets: prometheus.LinearBuckets(0.01, 0.01, 10),
+})
-	})
-)
 
 func ExampleTimer() {
 	// timer times this example function. It uses a Histogram, but a Summary

prometheus/examples_test.go

@@ -15,6 +15,7 @@ package prometheus_test
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"math"
 	"net/http"
@@ -24,12 +25,11 @@ import (
 
 	//nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility.
 	"github.com/golang/protobuf/proto"
+	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/expfmt"
 
-	dto "github.com/prometheus/client_model/go"
+	"git.internal/re/client_golang/prometheus"
-
+	"git.internal/re/client_golang/prometheus/promhttp"
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 func ExampleGauge() {
@@ -599,13 +599,123 @@ func ExampleNewConstHistogram() {
 	// >
 }
 
+func ExampleNewConstHistogram_WithExemplar() {
+	desc := prometheus.NewDesc(
+		"http_request_duration_seconds",
+		"A histogram of the HTTP request durations.",
+		[]string{"code", "method"},
+		prometheus.Labels{"owner": "example"},
+	)
+
+	// Create a constant histogram from values we got from a 3rd party telemetry system.
+	h := prometheus.MustNewConstHistogram(
+		desc,
+		4711, 403.34,
+		map[float64]uint64{25: 121, 50: 2403, 100: 3221, 200: 4233},
+		"200", "get",
+	)
+
+	// Wrap const histogram with exemplars for each bucket.
+	exemplarTs, _ := time.Parse(time.RFC850, "Monday, 02-Jan-06 15:04:05 GMT")
+	exemplarLabels := prometheus.Labels{"testName": "testVal"}
+	h = prometheus.MustNewMetricWithExemplars(
+		h,
+		prometheus.Exemplar{Labels: exemplarLabels, Timestamp: exemplarTs, Value: 24.0},
+		prometheus.Exemplar{Labels: exemplarLabels, Timestamp: exemplarTs, Value: 42.0},
+		prometheus.Exemplar{Labels: exemplarLabels, Timestamp: exemplarTs, Value: 89.0},
+		prometheus.Exemplar{Labels: exemplarLabels, Timestamp: exemplarTs, Value: 157.0},
+	)
+
+	// Just for demonstration, let's check the state of the histogram by
+	// (ab)using its Write method (which is usually only used by Prometheus
+	// internally).
+	metric := &dto.Metric{}
+	h.Write(metric)
+	fmt.Println(proto.MarshalTextString(metric))
+
+	// Output:
+	// label: <
+	//   name: "code"
+	//   value: "200"
+	// >
+	// label: <
+	//   name: "method"
+	//   value: "get"
+	// >
+	// label: <
+	//   name: "owner"
+	//   value: "example"
+	// >
+	// histogram: <
+	//   sample_count: 4711
+	//   sample_sum: 403.34
+	//   bucket: <
+	//     cumulative_count: 121
+	//     upper_bound: 25
+	//     exemplar: <
+	//       label: <
+	//         name: "testName"
+	//         value: "testVal"
+	//       >
+	//       value: 24
+	//       timestamp: <
+	//         seconds: 1136214245
+	//       >
+	//     >
+	//   >
+	//   bucket: <
+	//     cumulative_count: 2403
+	//     upper_bound: 50
+	//     exemplar: <
+	//       label: <
+	//         name: "testName"
+	//         value: "testVal"
+	//       >
+	//       value: 42
+	//       timestamp: <
+	//         seconds: 1136214245
+	//       >
+	//     >
+	//   >
+	//   bucket: <
+	//     cumulative_count: 3221
+	//     upper_bound: 100
+	//     exemplar: <
+	//       label: <
+	//         name: "testName"
+	//         value: "testVal"
+	//       >
+	//       value: 89
+	//       timestamp: <
+	//         seconds: 1136214245
+	//       >
+	//     >
+	//   >
+	//   bucket: <
+	//     cumulative_count: 4233
+	//     upper_bound: 200
+	//     exemplar: <
+	//       label: <
+	//         name: "testName"
+	//         value: "testVal"
+	//       >
+	//       value: 157
+	//       timestamp: <
+	//         seconds: 1136214245
+	//       >
+	//     >
+	//   >
+	// >
+}
+
 func ExampleAlreadyRegisteredError() {
 	reqCounter := prometheus.NewCounter(prometheus.CounterOpts{
 		Name: "requests_total",
 		Help: "The total number of requests served.",
 	})
 	if err := prometheus.Register(reqCounter); err != nil {
-		if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
+		are := &prometheus.AlreadyRegisteredError{}
+		if errors.As(err, are) {
 			// A counter for that metric has been registered before.
 			// Use the old counter from now on.
 			reqCounter = are.ExistingCollector.(prometheus.Counter)

prometheus/expvar_collector_test.go

@@ -21,7 +21,7 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 func ExampleNewExpvarCollector() {

prometheus/gauge.go

@@ -210,7 +210,8 @@ func (v *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) {
 // WithLabelValues works as GetMetricWithLabelValues, but panics where
 // GetMetricWithLabelValues would have returned an error. Not returning an
 // error allows shortcuts like
-//     myVec.WithLabelValues("404", "GET").Add(42)
+//
+//	myVec.WithLabelValues("404", "GET").Add(42)
 func (v *GaugeVec) WithLabelValues(lvs ...string) Gauge {
 	g, err := v.GetMetricWithLabelValues(lvs...)
 	if err != nil {
@@ -221,7 +222,8 @@ func (v *GaugeVec) WithLabelValues(lvs ...string) Gauge {
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. Not returning an error allows shortcuts like
-//     myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Add(42)
+//
+//	myVec.With(prometheus.Labels{"code": "404", "method": "GET"}).Add(42)
 func (v *GaugeVec) With(labels Labels) Gauge {
 	g, err := v.GetMetricWith(labels)
 	if err != nil {

prometheus/gen_go_collector_metrics_set.go

@@ -25,26 +25,41 @@ import (
 	"os"
 	"runtime"
 	"runtime/metrics"
-	"strconv"
 	"strings"
 	"text/template"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/internal"
+	"git.internal/re/client_golang/prometheus/internal"
+
+	"github.com/hashicorp/go-version"
 )
 
 func main() {
-	if len(os.Args) != 2 {
+	var givenVersion string
-		log.Fatal("requires Go version (e.g. go1.17) as an argument")
-	}
 	toolVersion := runtime.Version()
-	if majorVersion := toolVersion[:strings.LastIndexByte(toolVersion, '.')]; majorVersion != os.Args[1] {
+	if len(os.Args) != 2 {
-		log.Fatalf("using Go version %q but expected Go version %q", majorVersion, os.Args[1])
+		log.Printf("requires Go version (e.g. go1.17) as an argument. Since it is not specified, assuming %s.", toolVersion)
+		givenVersion = toolVersion
+	} else {
+		givenVersion = os.Args[1]
 	}
-	version, err := parseVersion(mv)
+	log.Printf("given version for Go: %s", givenVersion)
+	log.Printf("tool version for Go: %s", toolVersion)
+
+	tv, err := version.NewVersion(strings.TrimPrefix(givenVersion, "go"))
 	if err != nil {
-		log.Fatalf("parsing Go version: %v", err)
+		log.Fatal(err)
 	}
+	gv, err := version.NewVersion(strings.TrimPrefix(toolVersion, "go"))
+	if err != nil {
+		log.Fatal(err)
+	}
+	if !gv.Equal(tv) {
+		log.Fatalf("using Go version %q but expected Go version %q", tv, gv)
+	}
+
+	v := goVersion(gv.Segments()[1])
+	log.Printf("generating metrics for Go version %q", v)
 
 	// Generate code.
 	var buf bytes.Buffer
@@ -54,7 +69,7 @@ func main() {
 		Cardinality  int
 	}{
 		Descriptions: metrics.All(),
-		GoVersion:    version,
+		GoVersion:    v,
 		Cardinality:  rmCardinality(),
 	})
 	if err != nil {
@@ -68,7 +83,7 @@ func main() {
 	}
 
 	// Write it to a file.
-	fname := fmt.Sprintf("go_collector_metrics_%s_test.go", version.Abbr())
+	fname := fmt.Sprintf("go_collector_metrics_%s_test.go", v.Abbr())
 	if err := os.WriteFile(fname, result, 0o644); err != nil {
 		log.Fatalf("writing file: %v", err)
 	}
@@ -84,15 +99,6 @@ func (g goVersion) Abbr() string {
 	return fmt.Sprintf("go1%d", g)
 }
 
-func parseVersion(s string) (goVersion, error) {
-	i := strings.IndexRune(s, '.')
-	if i < 0 {
-		return goVersion(-1), fmt.Errorf("bad Go version format")
-	}
-	i, err := strconv.Atoi(s[i+1:])
-	return goVersion(i), err
-}
-
 func rmCardinality() int {
 	cardinality := 0
 
@@ -117,6 +123,7 @@ func rmCardinality() int {
 			name[strings.IndexRune(name, ':')+1:],
 		)
 		cardinality += len(buckets) + 3 // Plus total count, sum, and the implicit infinity bucket.
+
 		// runtime/metrics bucket boundaries are lower-bound-inclusive, but
 		// always represents each actual *boundary* so Buckets is always
 		// 1 longer than Counts, while in Prometheus the mapping is one-to-one,
@@ -128,6 +135,12 @@ func rmCardinality() int {
 			// We already counted the infinity bucket separately.
 			cardinality--
 		}
+		// Prometheus also doesn't have buckets for -Inf, so they need to be omitted.
+		// See the following PR for more information:
+		// https://git.internal/re/client_golang/pull/1049
+		if buckets[0] == math.Inf(-1) {
+			cardinality--
+		}
 	}
 
 	return cardinality

prometheus/get_pid.go

@@ -1,4 +1,4 @@
-// Copyright 2021 The Prometheus Authors
+// Copyright 2015 The Prometheus Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -11,17 +11,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !go1.15
+//go:build !js || wasm
-// +build !go1.15
+// +build !js wasm
 
-package collectors
+package prometheus
 
-import (
+import "os"
-	"database/sql"
 
-	"github.com/prometheus/client_golang/prometheus"
+func getPIDFn() func() (int, error) {
-)
+	pid := os.Getpid()
-
+	return func() (int, error) {
-func (c *dbStatsCollector) describeNewInGo115(ch chan<- *prometheus.Desc) {}
+		return pid, nil
-
+	}
-func (c *dbStatsCollector) collectNewInGo115(ch chan<- prometheus.Metric, stats sql.DBStats) {}
+}

prometheus/get_pid_gopherjs.go

@@ -0,0 +1,23 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build js && !wasm
+// +build js,!wasm
+
+package prometheus
+
+func getPIDFn() func() (int, error) {
+	return func() (int, error) {
+		return 1, nil
+	}
+}

prometheus/go_collector.go

@@ -19,6 +19,10 @@ import (
 	"time"
 )
 
+// goRuntimeMemStats provides the metrics initially provided by runtime.ReadMemStats.
+// From Go 1.17 those similar (and better) statistics are provided by runtime/metrics, so
+// while eval closure works on runtime.MemStats, the struct from Go 1.17+ is
+// populated using runtime/metrics.
 func goRuntimeMemStats() memStatsMetrics {
 	return memStatsMetrics{
 		{
@@ -224,7 +228,7 @@ func newBaseGoCollector() baseGoCollector {
 			"A summary of the pause duration of garbage collection cycles.",
 			nil, nil),
 		gcLastTimeDesc: NewDesc(
-			memstatNamespace("last_gc_time_seconds"),
+			"go_memstats_last_gc_time_seconds",
 			"Number of seconds since 1970 of last garbage collection.",
 			nil, nil),
 		goInfoDesc: NewDesc(
@@ -246,8 +250,9 @@ func (c *baseGoCollector) Describe(ch chan<- *Desc) {
 // Collect returns the current state of all metrics of the collector.
 func (c *baseGoCollector) Collect(ch chan<- Metric) {
 	ch <- MustNewConstMetric(c.goroutinesDesc, GaugeValue, float64(runtime.NumGoroutine()))
-	n, _ := runtime.ThreadCreateProfile(nil)
+
-	ch <- MustNewConstMetric(c.threadsDesc, GaugeValue, float64(n))
+	n := getRuntimeNumThreads()
+	ch <- MustNewConstMetric(c.threadsDesc, GaugeValue, n)
 
 	var stats debug.GCStats
 	stats.PauseQuantiles = make([]time.Duration, 5)
@@ -269,7 +274,6 @@ func memstatNamespace(s string) string {
 
 // memStatsMetrics provide description, evaluator, runtime/metrics name, and
 // value type for memstat metrics.
-// TODO(bwplotka): Remove with end Go 1.16 EOL and replace with runtime/metrics.Description
 type memStatsMetrics []struct {
 	desc    *Desc
 	eval    func(*runtime.MemStats) float64

prometheus/go_collector_go116.go

@@ -46,7 +46,7 @@ func NewGoCollector() Collector {
 		eval    func(*runtime.MemStats) float64
 		valType ValueType
 	}{
-		// This metric is omitted in Go1.17+, see https://github.com/prometheus/client_golang/issues/842#issuecomment-861812034
+		// This metric is omitted in Go1.17+, see https://git.internal/re/client_golang/issues/842#issuecomment-861812034
 		desc: NewDesc(
 			memstatNamespace("gc_cpu_fraction"),
 			"The fraction of this program's available CPU time used by the GC since the program started.",

prometheus/go_collector_latest.go

@@ -27,13 +27,15 @@ import (
 	"github.com/golang/protobuf/proto"
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/client_golang/prometheus/internal"
+	"git.internal/re/client_golang/prometheus/internal"
 )
 
 const (
+	// constants for strings referenced more than once.
 	goGCHeapTinyAllocsObjects               = "/gc/heap/tiny/allocs:objects"
 	goGCHeapAllocsObjects                   = "/gc/heap/allocs:objects"
 	goGCHeapFreesObjects                    = "/gc/heap/frees:objects"
+	goGCHeapFreesBytes                      = "/gc/heap/frees:bytes"
 	goGCHeapAllocsBytes                     = "/gc/heap/allocs:bytes"
 	goGCHeapObjects                         = "/gc/heap/objects:objects"
 	goGCHeapGoalBytes                       = "/gc/heap/goal:bytes"
@@ -53,8 +55,9 @@ const (
 	goMemoryClassesOtherBytes               = "/memory/classes/other:bytes"
 )
 
-// runtime/metrics names required for runtimeMemStats like logic.
+// rmNamesForMemStatsMetrics represents runtime/metrics names required to populate goRuntimeMemStats from like logic.
-var rmForMemStats = []string{goGCHeapTinyAllocsObjects,
+var rmNamesForMemStatsMetrics = []string{
+	goGCHeapTinyAllocsObjects,
 	goGCHeapAllocsObjects,
 	goGCHeapFreesObjects,
 	goGCHeapAllocsBytes,
@@ -89,74 +92,90 @@ func bestEffortLookupRM(lookup []string) []metrics.Description {
 }
 
 type goCollector struct {
-	opt  GoCollectorOptions
 	base baseGoCollector
 
 	// mu protects updates to all fields ensuring a consistent
 	// snapshot is always produced by Collect.
 	mu sync.Mutex
 
-	// rm... fields all pertain to the runtime/metrics package.
+	// Contains all samples that has to retrieved from runtime/metrics (not all of them will be exposed).
-	rmSampleBuf []metrics.Sample
+	sampleBuf []metrics.Sample
-	rmSampleMap map[string]*metrics.Sample
+	// sampleMap allows lookup for MemStats metrics and runtime/metrics histograms for exact sums.
-	rmMetrics   []collectorMetric
+	sampleMap map[string]*metrics.Sample
+
+	// rmExposedMetrics represents all runtime/metrics package metrics
+	// that were configured to be exposed.
+	rmExposedMetrics     []collectorMetric
+	rmExactSumMapForHist map[string]string
 
 	// With Go 1.17, the runtime/metrics package was introduced.
 	// From that point on, metric names produced by the runtime/metrics
 	// package could be generated from runtime/metrics names. However,
 	// these differ from the old names for the same values.
 	//
-	// This field exist to export the same values under the old names
+	// This field exists to export the same values under the old names
 	// as well.
-	msMetrics memStatsMetrics
+	msMetrics        memStatsMetrics
+	msMetricsEnabled bool
 }
 
-const (
+type rmMetricDesc struct {
-	// Those are not exposed due to need to move Go collector to another package in v2.
+	metrics.Description
-	// See issue https://github.com/prometheus/client_golang/issues/1030.
-	goRuntimeMemStatsCollection uint32 = 1 << iota
-	goRuntimeMetricsCollection
-)
-
-// GoCollectorOptions should not be used be directly by anything, except `collectors` package.
-// Use it via collectors package instead. See issue
-// https://github.com/prometheus/client_golang/issues/1030.
-//
-// Deprecated: Use collectors.WithGoCollections
-type GoCollectorOptions struct {
-	// EnabledCollection sets what type of collections collector should expose on top of base collection.
-	// By default it's goMemStatsCollection | goRuntimeMetricsCollection.
-	EnabledCollections uint32
 }
 
-func (c GoCollectorOptions) isEnabled(flag uint32) bool {
+func matchRuntimeMetricsRules(rules []internal.GoCollectorRule) []rmMetricDesc {
-	return c.EnabledCollections&flag != 0
+	var descs []rmMetricDesc
+	for _, d := range metrics.All() {
+		var (
+			deny = true
+			desc rmMetricDesc
+		)
+
+		for _, r := range rules {
+			if !r.Matcher.MatchString(d.Name) {
+				continue
+			}
+			deny = r.Deny
+		}
+		if deny {
+			continue
+		}
+
+		desc.Description = d
+		descs = append(descs, desc)
+	}
+	return descs
 }
 
-const defaultGoCollections = goRuntimeMemStatsCollection
+func defaultGoCollectorOptions() internal.GoCollectorOptions {
+	return internal.GoCollectorOptions{
+		RuntimeMetricSumForHist: map[string]string{
+			"/gc/heap/allocs-by-size:bytes": goGCHeapAllocsBytes,
+			"/gc/heap/frees-by-size:bytes":  goGCHeapFreesBytes,
+		},
+		RuntimeMetricRules: []internal.GoCollectorRule{
+			//{Matcher: regexp.MustCompile("")},
+		},
+	}
+}
 
 // NewGoCollector is the obsolete version of collectors.NewGoCollector.
 // See there for documentation.
 //
 // Deprecated: Use collectors.NewGoCollector instead.
-func NewGoCollector(opts ...func(o *GoCollectorOptions)) Collector {
+func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) Collector {
-	opt := GoCollectorOptions{EnabledCollections: defaultGoCollections}
+	opt := defaultGoCollectorOptions()
 	for _, o := range opts {
 		o(&opt)
 	}
 
-	var descriptions []metrics.Description
+	exposedDescriptions := matchRuntimeMetricsRules(opt.RuntimeMetricRules)
-	if opt.isEnabled(goRuntimeMetricsCollection) {
-		descriptions = metrics.All()
-	} else if opt.isEnabled(goRuntimeMemStatsCollection) {
-		descriptions = bestEffortLookupRM(rmForMemStats)
-	}
 
 	// Collect all histogram samples so that we can get their buckets.
 	// The API guarantees that the buckets are always fixed for the lifetime
 	// of the process.
 	var histograms []metrics.Sample
-	for _, d := range descriptions {
+	for _, d := range exposedDescriptions {
 		if d.Kind == metrics.KindFloat64Histogram {
 			histograms = append(histograms, metrics.Sample{Name: d.Name})
 		}
@@ -171,13 +190,14 @@ func NewGoCollector(opts ...func(o *GoCollectorOptions)) Collector {
 		bucketsMap[histograms[i].Name] = histograms[i].Value.Float64Histogram().Buckets
 	}
 
-	// Generate a Desc and ValueType for each runtime/metrics metric.
+	// Generate a collector for each exposed runtime/metrics metric.
-	metricSet := make([]collectorMetric, 0, len(descriptions))
+	metricSet := make([]collectorMetric, 0, len(exposedDescriptions))
-	sampleBuf := make([]metrics.Sample, 0, len(descriptions))
+	// SampleBuf is used for reading from runtime/metrics.
-	sampleMap := make(map[string]*metrics.Sample, len(descriptions))
+	// We are assuming the largest case to have stable pointers for sampleMap purposes.
-	for i := range descriptions {
+	sampleBuf := make([]metrics.Sample, 0, len(exposedDescriptions)+len(opt.RuntimeMetricSumForHist)+len(rmNamesForMemStatsMetrics))
-		d := &descriptions[i]
+	sampleMap := make(map[string]*metrics.Sample, len(exposedDescriptions))
-		namespace, subsystem, name, ok := internal.RuntimeMetricsToProm(d)
+	for _, d := range exposedDescriptions {
+		namespace, subsystem, name, ok := internal.RuntimeMetricsToProm(&d.Description)
 		if !ok {
 			// Just ignore this metric; we can't do anything with it here.
 			// If a user decides to use the latest version of Go, we don't want
@@ -185,19 +205,17 @@ func NewGoCollector(opts ...func(o *GoCollectorOptions)) Collector {
 			continue
 		}
 
-		// Set up sample buffer for reading, and a map
-		// for quick lookup of sample values.
 		sampleBuf = append(sampleBuf, metrics.Sample{Name: d.Name})
 		sampleMap[d.Name] = &sampleBuf[len(sampleBuf)-1]
 
 		var m collectorMetric
 		if d.Kind == metrics.KindFloat64Histogram {
-			_, hasSum := rmExactSumMap[d.Name]
+			_, hasSum := opt.RuntimeMetricSumForHist[d.Name]
 			unit := d.Name[strings.IndexRune(d.Name, ':')+1:]
 			m = newBatchHistogram(
 				NewDesc(
 					BuildFQName(namespace, subsystem, name),
-					d.Description,
+					d.Description.Description,
 					nil,
 					nil,
 				),
@@ -209,30 +227,61 @@ func NewGoCollector(opts ...func(o *GoCollectorOptions)) Collector {
 				Namespace: namespace,
 				Subsystem: subsystem,
 				Name:      name,
-				Help:      d.Description,
+				Help:      d.Description.Description,
-			})
+			},
+			)
 		} else {
 			m = NewGauge(GaugeOpts{
 				Namespace: namespace,
 				Subsystem: subsystem,
 				Name:      name,
-				Help:      d.Description,
+				Help:      d.Description.Description,
 			})
 		}
 		metricSet = append(metricSet, m)
 	}
 
-	var msMetrics memStatsMetrics
+	// Add exact sum metrics to sampleBuf if not added before.
-	if opt.isEnabled(goRuntimeMemStatsCollection) {
+	for _, h := range histograms {
-		msMetrics = goRuntimeMemStats()
+		sumMetric, ok := opt.RuntimeMetricSumForHist[h.Name]
+		if !ok {
+			continue
+		}
+
+		if _, ok := sampleMap[sumMetric]; ok {
+			continue
+		}
+		sampleBuf = append(sampleBuf, metrics.Sample{Name: sumMetric})
+		sampleMap[sumMetric] = &sampleBuf[len(sampleBuf)-1]
 	}
+
+	var (
+		msMetrics      memStatsMetrics
+		msDescriptions []metrics.Description
+	)
+
+	if !opt.DisableMemStatsLikeMetrics {
+		msMetrics = goRuntimeMemStats()
+		msDescriptions = bestEffortLookupRM(rmNamesForMemStatsMetrics)
+
+		// Check if metric was not exposed before and if not, add to sampleBuf.
+		for _, mdDesc := range msDescriptions {
+			if _, ok := sampleMap[mdDesc.Name]; ok {
+				continue
+			}
+			sampleBuf = append(sampleBuf, metrics.Sample{Name: mdDesc.Name})
+			sampleMap[mdDesc.Name] = &sampleBuf[len(sampleBuf)-1]
+		}
+	}
+
 	return &goCollector{
-		opt:         opt,
+		base:                 newBaseGoCollector(),
-		base:        newBaseGoCollector(),
+		sampleBuf:            sampleBuf,
-		rmSampleBuf: sampleBuf,
+		sampleMap:            sampleMap,
-		rmSampleMap: sampleMap,
+		rmExposedMetrics:     metricSet,
-		rmMetrics:   metricSet,
+		rmExactSumMapForHist: opt.RuntimeMetricSumForHist,
-		msMetrics:   msMetrics,
+		msMetrics:            msMetrics,
+		msMetricsEnabled:     !opt.DisableMemStatsLikeMetrics,
 	}
 }
 
@@ -242,7 +291,7 @@ func (c *goCollector) Describe(ch chan<- *Desc) {
 	for _, i := range c.msMetrics {
 		ch <- i.desc
 	}
-	for _, m := range c.rmMetrics {
+	for _, m := range c.rmExposedMetrics {
 		ch <- m.Desc()
 	}
 }
@@ -252,8 +301,12 @@ func (c *goCollector) Collect(ch chan<- Metric) {
 	// Collect base non-memory metrics.
 	c.base.Collect(ch)
 
+	if len(c.sampleBuf) == 0 {
+		return
+	}
+
 	// Collect must be thread-safe, so prevent concurrent use of
-	// rmSampleBuf. Just read into rmSampleBuf but write all the data
+	// sampleBuf elements. Just read into sampleBuf but write all the data
 	// we get into our Metrics or MemStats.
 	//
 	// This lock also ensures that the Metrics we send out are all from
@@ -267,44 +320,43 @@ func (c *goCollector) Collect(ch chan<- Metric) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	if len(c.rmSampleBuf) > 0 {
+	// Populate runtime/metrics sample buffer.
-		// Populate runtime/metrics sample buffer.
+	metrics.Read(c.sampleBuf)
-		metrics.Read(c.rmSampleBuf)
-	}
 
-	if c.opt.isEnabled(goRuntimeMetricsCollection) {
+	// Collect all our runtime/metrics user chose to expose from sampleBuf (if any).
-		// Collect all our metrics from rmSampleBuf.
+	for i, metric := range c.rmExposedMetrics {
-		for i, sample := range c.rmSampleBuf {
+		// We created samples for exposed metrics first in order, so indexes match.
-			// N.B. switch on concrete type because it's significantly more efficient
+		sample := c.sampleBuf[i]
-			// than checking for the Counter and Gauge interface implementations. In
+
-			// this case, we control all the types here.
+		// N.B. switch on concrete type because it's significantly more efficient
-			switch m := c.rmMetrics[i].(type) {
+		// than checking for the Counter and Gauge interface implementations. In
-			case *counter:
+		// this case, we control all the types here.
-				// Guard against decreases. This should never happen, but a failure
+		switch m := metric.(type) {
-				// to do so will result in a panic, which is a harsh consequence for
+		case *counter:
-				// a metrics collection bug.
+			// Guard against decreases. This should never happen, but a failure
-				v0, v1 := m.get(), unwrapScalarRMValue(sample.Value)
+			// to do so will result in a panic, which is a harsh consequence for
-				if v1 > v0 {
+			// a metrics collection bug.
-					m.Add(unwrapScalarRMValue(sample.Value) - m.get())
+			v0, v1 := m.get(), unwrapScalarRMValue(sample.Value)
-				}
+			if v1 > v0 {
-				m.Collect(ch)
+				m.Add(unwrapScalarRMValue(sample.Value) - m.get())
-			case *gauge:
-				m.Set(unwrapScalarRMValue(sample.Value))
-				m.Collect(ch)
-			case *batchHistogram:
-				m.update(sample.Value.Float64Histogram(), c.exactSumFor(sample.Name))
-				m.Collect(ch)
-			default:
-				panic("unexpected metric type")
 			}
+			m.Collect(ch)
+		case *gauge:
+			m.Set(unwrapScalarRMValue(sample.Value))
+			m.Collect(ch)
+		case *batchHistogram:
+			m.update(sample.Value.Float64Histogram(), c.exactSumFor(sample.Name))
+			m.Collect(ch)
+		default:
+			panic("unexpected metric type")
 		}
 	}
 
-	// ms is a dummy MemStats that we populate ourselves so that we can
+	if c.msMetricsEnabled {
-	// populate the old metrics from it if goMemStatsCollection is enabled.
+		// ms is a dummy MemStats that we populate ourselves so that we can
-	if c.opt.isEnabled(goRuntimeMemStatsCollection) {
+		// populate the old metrics from it if goMemStatsCollection is enabled.
 		var ms runtime.MemStats
-		memStatsFromRM(&ms, c.rmSampleMap)
+		memStatsFromRM(&ms, c.sampleMap)
 		for _, i := range c.msMetrics {
 			ch <- MustNewConstMetric(i.desc, i.valType, i.eval(&ms))
 		}
@@ -335,11 +387,6 @@ func unwrapScalarRMValue(v metrics.Value) float64 {
 	}
 }
 
-var rmExactSumMap = map[string]string{
-	"/gc/heap/allocs-by-size:bytes": "/gc/heap/allocs:bytes",
-	"/gc/heap/frees-by-size:bytes":  "/gc/heap/frees:bytes",
-}
-
 // exactSumFor takes a runtime/metrics metric name (that is assumed to
 // be of kind KindFloat64Histogram) and returns its exact sum and whether
 // its exact sum exists.
@@ -347,11 +394,11 @@ var rmExactSumMap = map[string]string{
 // The runtime/metrics API for histograms doesn't currently expose exact
 // sums, but some of the other metrics are in fact exact sums of histograms.
 func (c *goCollector) exactSumFor(rmName string) float64 {
-	sumName, ok := rmExactSumMap[rmName]
+	sumName, ok := c.rmExactSumMapForHist[rmName]
 	if !ok {
 		return 0
 	}
-	s, ok := c.rmSampleMap[sumName]
+	s, ok := c.sampleMap[sumName]
 	if !ok {
 		return 0
 	}
@@ -400,7 +447,7 @@ func memStatsFromRM(ms *runtime.MemStats, rm map[string]*metrics.Sample) {
 	// N.B. GCCPUFraction is intentionally omitted. This metric is not useful,
 	// and often misleading due to the fact that it's an average over the lifetime
 	// of the process.
-	// See https://github.com/prometheus/client_golang/issues/842#issuecomment-861812034
+	// See https://git.internal/re/client_golang/issues/842#issuecomment-861812034
 	// for more details.
 	ms.GCCPUFraction = 0
 }

prometheus/go_collector_latest_test.go

@@ -19,6 +19,7 @@ package prometheus
 import (
 	"math"
 	"reflect"
+	"regexp"
 	"runtime"
 	"runtime/metrics"
 	"sync"
@@ -26,13 +27,22 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/client_golang/prometheus/internal"
+	"git.internal/re/client_golang/prometheus/internal"
 )
 
 func TestRmForMemStats(t *testing.T) {
-	if got, want := len(bestEffortLookupRM(rmForMemStats)), len(rmForMemStats); got != want {
+	descs := bestEffortLookupRM(rmNamesForMemStatsMetrics)
+
+	if got, want := len(descs), len(rmNamesForMemStatsMetrics); got != want {
 		t.Errorf("got %d, want %d metrics", got, want)
 	}
+
+	for _, d := range descs {
+		// We don't expect histograms there.
+		if d.Kind == metrics.KindFloat64Histogram {
+			t.Errorf("we don't expect to use histograms for MemStats metrics, got %v", d.Name)
+		}
+	}
 }
 
 func expectedBaseMetrics() map[string]struct{} {
@@ -64,30 +74,43 @@ func addExpectedRuntimeMetrics(metrics map[string]struct{}) map[string]struct{}
 	return metrics
 }
 
-func TestGoCollector(t *testing.T) {
+func TestGoCollector_ExposedMetrics(t *testing.T) {
 	for _, tcase := range []struct {
-		collections       uint32
+		opts              internal.GoCollectorOptions
 		expectedFQNameSet map[string]struct{}
 	}{
 		{
-			collections:       0,
+			opts: internal.GoCollectorOptions{
+				DisableMemStatsLikeMetrics: true,
+			},
 			expectedFQNameSet: expectedBaseMetrics(),
 		},
 		{
-			collections:       goRuntimeMemStatsCollection,
+			// Default, only MemStats.
 			expectedFQNameSet: addExpectedRuntimeMemStats(expectedBaseMetrics()),
 		},
 		{
-			collections:       goRuntimeMetricsCollection,
+			// Get all runtime/metrics without MemStats.
+			opts: internal.GoCollectorOptions{
+				DisableMemStatsLikeMetrics: true,
+				RuntimeMetricRules: []internal.GoCollectorRule{
+					{Matcher: regexp.MustCompile("/.*")},
+				},
+			},
 			expectedFQNameSet: addExpectedRuntimeMetrics(expectedBaseMetrics()),
 		},
 		{
-			collections:       goRuntimeMemStatsCollection | goRuntimeMetricsCollection,
+			// Get all runtime/metrics and MemStats.
+			opts: internal.GoCollectorOptions{
+				RuntimeMetricRules: []internal.GoCollectorRule{
+					{Matcher: regexp.MustCompile("/.*")},
+				},
+			},
 			expectedFQNameSet: addExpectedRuntimeMemStats(addExpectedRuntimeMetrics(expectedBaseMetrics())),
 		},
 	} {
 		if ok := t.Run("", func(t *testing.T) {
-			goMetrics := collectGoMetrics(t, tcase.collections)
+			goMetrics := collectGoMetrics(t, tcase.opts)
 			goMetricSet := make(map[string]Metric)
 			for _, m := range goMetrics {
 				goMetricSet[m.Desc().fqName] = m
@@ -118,7 +141,11 @@ func TestGoCollector(t *testing.T) {
 var sink interface{}
 
 func TestBatchHistogram(t *testing.T) {
-	goMetrics := collectGoMetrics(t, goRuntimeMetricsCollection)
+	goMetrics := collectGoMetrics(t, internal.GoCollectorOptions{
+		RuntimeMetricRules: []internal.GoCollectorRule{
+			{Matcher: regexp.MustCompile("/.*")},
+		},
+	})
 
 	var mhist Metric
 	for _, m := range goMetrics {
@@ -145,7 +172,8 @@ func TestBatchHistogram(t *testing.T) {
 	for i := 0; i < 100; i++ {
 		sink = make([]byte, 128)
 	}
-	collectGoMetrics(t, defaultGoCollections)
+
+	collectGoMetrics(t, defaultGoCollectorOptions())
 	for i, v := range hist.counts {
 		if v != countsCopy[i] {
 			t.Error("counts changed during new collection")
@@ -194,11 +222,13 @@ func TestBatchHistogram(t *testing.T) {
 	}
 }
 
-func collectGoMetrics(t *testing.T, enabledCollections uint32) []Metric {
+func collectGoMetrics(t *testing.T, opts internal.GoCollectorOptions) []Metric {
 	t.Helper()
 
-	c := NewGoCollector(func(o *GoCollectorOptions) {
+	c := NewGoCollector(func(o *internal.GoCollectorOptions) {
-		o.EnabledCollections = enabledCollections
+		o.DisableMemStatsLikeMetrics = opts.DisableMemStatsLikeMetrics
+		o.RuntimeMetricSumForHist = opts.RuntimeMetricSumForHist
+		o.RuntimeMetricRules = opts.RuntimeMetricRules
 	}).(*goCollector)
 
 	// Collect all metrics.
@@ -222,7 +252,7 @@ func collectGoMetrics(t *testing.T, enabledCollections uint32) []Metric {
 
 func TestMemStatsEquivalence(t *testing.T) {
 	var msReal, msFake runtime.MemStats
-	descs := bestEffortLookupRM(rmForMemStats)
+	descs := bestEffortLookupRM(rmNamesForMemStatsMetrics)
 
 	samples := make([]metrics.Sample, len(descs))
 	samplesMap := make(map[string]*metrics.Sample)
@@ -269,7 +299,12 @@ func TestMemStatsEquivalence(t *testing.T) {
 }
 
 func TestExpectedRuntimeMetrics(t *testing.T) {
-	goMetrics := collectGoMetrics(t, goRuntimeMetricsCollection)
+	goMetrics := collectGoMetrics(t, internal.GoCollectorOptions{
+		DisableMemStatsLikeMetrics: true,
+		RuntimeMetricRules: []internal.GoCollectorRule{
+			{Matcher: regexp.MustCompile("/.*")},
+		},
+	})
 	goMetricSet := make(map[string]Metric)
 	for _, m := range goMetrics {
 		goMetricSet[m.Desc().fqName] = m

prometheus/go_collector_metrics_go119_test.go

@@ -0,0 +1,45 @@
+// Code generated by gen_go_collector_metrics_set.go; DO NOT EDIT.
+//go:generate go run gen_go_collector_metrics_set.go go1.19
+
+//go:build go1.19 && !go1.20
+// +build go1.19,!go1.20
+
+package prometheus
+
+var expectedRuntimeMetrics = map[string]string{
+	"/cgo/go-to-c-calls:calls":                    "go_cgo_go_to_c_calls_calls_total",
+	"/gc/cycles/automatic:gc-cycles":              "go_gc_cycles_automatic_gc_cycles_total",
+	"/gc/cycles/forced:gc-cycles":                 "go_gc_cycles_forced_gc_cycles_total",
+	"/gc/cycles/total:gc-cycles":                  "go_gc_cycles_total_gc_cycles_total",
+	"/gc/heap/allocs-by-size:bytes":               "go_gc_heap_allocs_by_size_bytes",
+	"/gc/heap/allocs:bytes":                       "go_gc_heap_allocs_bytes_total",
+	"/gc/heap/allocs:objects":                     "go_gc_heap_allocs_objects_total",
+	"/gc/heap/frees-by-size:bytes":                "go_gc_heap_frees_by_size_bytes",
+	"/gc/heap/frees:bytes":                        "go_gc_heap_frees_bytes_total",
+	"/gc/heap/frees:objects":                      "go_gc_heap_frees_objects_total",
+	"/gc/heap/goal:bytes":                         "go_gc_heap_goal_bytes",
+	"/gc/heap/objects:objects":                    "go_gc_heap_objects_objects",
+	"/gc/heap/tiny/allocs:objects":                "go_gc_heap_tiny_allocs_objects_total",
+	"/gc/limiter/last-enabled:gc-cycle":           "go_gc_limiter_last_enabled_gc_cycle",
+	"/gc/pauses:seconds":                          "go_gc_pauses_seconds",
+	"/gc/stack/starting-size:bytes":               "go_gc_stack_starting_size_bytes",
+	"/memory/classes/heap/free:bytes":             "go_memory_classes_heap_free_bytes",
+	"/memory/classes/heap/objects:bytes":          "go_memory_classes_heap_objects_bytes",
+	"/memory/classes/heap/released:bytes":         "go_memory_classes_heap_released_bytes",
+	"/memory/classes/heap/stacks:bytes":           "go_memory_classes_heap_stacks_bytes",
+	"/memory/classes/heap/unused:bytes":           "go_memory_classes_heap_unused_bytes",
+	"/memory/classes/metadata/mcache/free:bytes":  "go_memory_classes_metadata_mcache_free_bytes",
+	"/memory/classes/metadata/mcache/inuse:bytes": "go_memory_classes_metadata_mcache_inuse_bytes",
+	"/memory/classes/metadata/mspan/free:bytes":   "go_memory_classes_metadata_mspan_free_bytes",
+	"/memory/classes/metadata/mspan/inuse:bytes":  "go_memory_classes_metadata_mspan_inuse_bytes",
+	"/memory/classes/metadata/other:bytes":        "go_memory_classes_metadata_other_bytes",
+	"/memory/classes/os-stacks:bytes":             "go_memory_classes_os_stacks_bytes",
+	"/memory/classes/other:bytes":                 "go_memory_classes_other_bytes",
+	"/memory/classes/profiling/buckets:bytes":     "go_memory_classes_profiling_buckets_bytes",
+	"/memory/classes/total:bytes":                 "go_memory_classes_total_bytes",
+	"/sched/gomaxprocs:threads":                   "go_sched_gomaxprocs_threads",
+	"/sched/goroutines:goroutines":                "go_sched_goroutines_goroutines",
+	"/sched/latencies:seconds":                    "go_sched_latencies_seconds",
+}
+
+const expectedRuntimeMetricsCardinality = 81

prometheus/graphite/bridge.go

@@ -30,7 +30,7 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 const (
@@ -197,14 +197,16 @@ func writeMetrics(w io.Writer, mfs []*dto.MetricFamily, useTags bool, prefix str
 
 	buf := bufio.NewWriter(w)
 	for _, s := range vec {
-		for _, c := range prefix {
+		if prefix != "" {
-			if _, err := buf.WriteRune(c); err != nil {
+			for _, c := range prefix {
+				if _, err := buf.WriteRune(c); err != nil {
+					return err
+				}
+			}
+			if err := buf.WriteByte('.'); err != nil {
 				return err
 			}
 		}
-		if err := buf.WriteByte('.'); err != nil {
-			return err
-		}
 		if err := writeMetric(buf, s.Metric, useTags); err != nil {
 			return err
 		}
@@ -238,9 +240,8 @@ func writeMetric(buf *bufio.Writer, m model.Metric, useTags bool) error {
 		}
 		if useTags {
 			return writeTags(buf, m)
-		} else {
-			return writeLabels(buf, m, numLabels)
 		}
+		return writeLabels(buf, m, numLabels)
 	}
 	return nil
 }

prometheus/graphite/bridge_test.go

@@ -31,7 +31,7 @@ import (
 
 	"github.com/prometheus/common/model"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 func TestSanitize(t *testing.T) {
@@ -101,6 +101,7 @@ func testWriteSummary(t *testing.T, useTags bool) {
 		{prefix: "prefix"},
 		{prefix: "pre/fix"},
 		{prefix: "pre.fix"},
+		{prefix: ""},
 	}
 
 	var (
@@ -141,10 +142,15 @@ func testWriteSummary(t *testing.T, useTags bool) {
 			t.Fatalf("error: %v", err)
 		}
 
-		wantWithPrefix := fmt.Sprintf(want,
+		var wantWithPrefix string
-			tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
+		if tc.prefix == "" {
-			tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
+			wantWithPrefix = strings.ReplaceAll(want, "%s.", "")
-		)
+		} else {
+			wantWithPrefix = fmt.Sprintf(want,
+				tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
+				tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
+			)
+		}
 
 		got := buf.String()
 

prometheus/histogram_test.go

@@ -20,6 +20,7 @@ import (
 	"runtime"
 	"sort"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"testing/quick"
 	"time"
@@ -28,6 +29,8 @@ import (
 	"github.com/golang/protobuf/proto"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
+	"git.internal/re/client_golang/prometheus/internal"
+
 	dto "github.com/prometheus/client_model/go"
 )
 
@@ -167,7 +170,7 @@ func TestHistogramConcurrency(t *testing.T) {
 		start.Add(1)
 		end.Add(concLevel)
 
-		sum := NewHistogram(HistogramOpts{
+		his := NewHistogram(HistogramOpts{
 			Name:    "test_histogram",
 			Help:    "helpless",
 			Buckets: testBuckets,
@@ -188,9 +191,9 @@ func TestHistogramConcurrency(t *testing.T) {
 				start.Wait()
 				for _, v := range vals {
 					if n%2 == 0 {
-						sum.Observe(v)
+						his.Observe(v)
 					} else {
-						sum.(ExemplarObserver).ObserveWithExemplar(v, Labels{"foo": "bar"})
+						his.(ExemplarObserver).ObserveWithExemplar(v, Labels{"foo": "bar"})
 					}
 				}
 				end.Done()
@@ -201,7 +204,7 @@ func TestHistogramConcurrency(t *testing.T) {
 		end.Wait()
 
 		m := &dto.Metric{}
-		sum.Write(m)
+		his.Write(m)
 		if got, want := int(*m.Histogram.SampleCount), total; got != want {
 			t.Errorf("got sample count %d, want %d", got, want)
 		}
@@ -354,13 +357,13 @@ func TestBuckets(t *testing.T) {
 	}
 
 	got = ExponentialBucketsRange(1, 100, 10)
-	want = []float64{1.0, 1.6681005372000588, 2.782559402207125,
+	want = []float64{
-		4.641588833612779, 7.742636826811273, 12.915496650148842,
+		1.0, 1.6681, 2.7825, 4.6415, 7.7426, 12.9154, 21.5443,
-		21.544346900318846, 35.93813663804629, 59.94842503189414,
+		35.9381, 59.9484, 100.0000,
-		100.00000000000007,
 	}
-	if !reflect.DeepEqual(got, want) {
+	const epsilon = 0.0001
-		t.Errorf("exponential buckets range: got %v, want %v", got, want)
+	if !internal.AlmostEqualFloat64s(got, want, epsilon) {
+		t.Errorf("exponential buckets range: got %v, want %v (epsilon %f)", got, want, epsilon)
 	}
 }
 
@@ -424,24 +427,24 @@ func TestHistogramExemplar(t *testing.T) {
 	}
 	expectedExemplars := []*dto.Exemplar{
 		nil,
-		&dto.Exemplar{
+		{
 			Label: []*dto.LabelPair{
-				&dto.LabelPair{Name: proto.String("id"), Value: proto.String("2")},
+				{Name: proto.String("id"), Value: proto.String("2")},
 			},
 			Value:     proto.Float64(1.6),
 			Timestamp: ts,
 		},
 		nil,
-		&dto.Exemplar{
+		{
 			Label: []*dto.LabelPair{
-				&dto.LabelPair{Name: proto.String("id"), Value: proto.String("3")},
+				{Name: proto.String("id"), Value: proto.String("3")},
 			},
 			Value:     proto.Float64(4),
 			Timestamp: ts,
 		},
-		&dto.Exemplar{
+		{
 			Label: []*dto.LabelPair{
-				&dto.LabelPair{Name: proto.String("id"), Value: proto.String("4")},
+				{Name: proto.String("id"), Value: proto.String("4")},
 			},
 			Value:     proto.Float64(4.5),
 			Timestamp: ts,
@@ -466,3 +469,408 @@ func TestHistogramExemplar(t *testing.T) {
 		}
 	}
 }
+
+func TestNativeHistogram(t *testing.T) {
+	scenarios := []struct {
+		name             string
+		observations     []float64 // With simulated interval of 1m.
+		factor           float64
+		zeroThreshold    float64
+		maxBuckets       uint32
+		minResetDuration time.Duration
+		maxZeroThreshold float64
+		want             string // String representation of protobuf.
+	}{
+		{
+			name:         "no sparse buckets",
+			observations: []float64{1, 2, 3},
+			factor:       1,
+			want:         `sample_count:3 sample_sum:6 bucket:<cumulative_count:0 upper_bound:0.005 > bucket:<cumulative_count:0 upper_bound:0.01 > bucket:<cumulative_count:0 upper_bound:0.025 > bucket:<cumulative_count:0 upper_bound:0.05 > bucket:<cumulative_count:0 upper_bound:0.1 > bucket:<cumulative_count:0 upper_bound:0.25 > bucket:<cumulative_count:0 upper_bound:0.5 > bucket:<cumulative_count:1 upper_bound:1 > bucket:<cumulative_count:2 upper_bound:2.5 > bucket:<cumulative_count:3 upper_bound:5 > bucket:<cumulative_count:3 upper_bound:10 > `, // Has conventional buckets because there are no sparse buckets.
+		},
+		{
+			name:         "factor 1.1 results in schema 3",
+			observations: []float64{0, 1, 2, 3},
+			factor:       1.1,
+			want:         `sample_count:4 sample_sum:6 schema:3 zero_threshold:2.938735877055719e-39 zero_count:1 positive_span:<offset:0 length:1 > positive_span:<offset:7 length:1 > positive_span:<offset:4 length:1 > positive_delta:1 positive_delta:0 positive_delta:0 `,
+		},
+		{
+			name:         "factor 1.2 results in schema 2",
+			observations: []float64{0, 1, 1.2, 1.4, 1.8, 2},
+			factor:       1.2,
+			want:         `sample_count:6 sample_sum:7.4 schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 positive_span:<offset:0 length:5 > positive_delta:1 positive_delta:-1 positive_delta:2 positive_delta:-2 positive_delta:2 `,
+		},
+		{
+			name: "factor 4 results in schema -1",
+			observations: []float64{
+				0.5, 1, // Bucket 0: (0.25, 1]
+				1.5, 2, 3, 3.5, // Bucket 1: (1, 4]
+				5, 6, 7, // Bucket 2: (4, 16]
+				33.33, // Bucket 3: (16, 64]
+			},
+			factor: 4,
+			want:   `sample_count:10 sample_sum:62.83 schema:-1 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:0 length:4 > positive_delta:2 positive_delta:2 positive_delta:-1 positive_delta:-2 `,
+		},
+		{
+			name: "factor 17 results in schema -2",
+			observations: []float64{
+				0.5, 1, // Bucket 0: (0.0625, 1]
+				1.5, 2, 3, 3.5, 5, 6, 7, // Bucket 1: (1, 16]
+				33.33, // Bucket 2: (16, 256]
+			},
+			factor: 17,
+			want:   `sample_count:10 sample_sum:62.83 schema:-2 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:0 length:3 > positive_delta:2 positive_delta:5 positive_delta:-6 `,
+		},
+		{
+			name:         "negative buckets",
+			observations: []float64{0, -1, -1.2, -1.4, -1.8, -2},
+			factor:       1.2,
+			want:         `sample_count:6 sample_sum:-7.4 schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 negative_span:<offset:0 length:5 > negative_delta:1 negative_delta:-1 negative_delta:2 negative_delta:-2 negative_delta:2 `,
+		},
+		{
+			name:         "negative and positive buckets",
+			observations: []float64{0, -1, -1.2, -1.4, -1.8, -2, 1, 1.2, 1.4, 1.8, 2},
+			factor:       1.2,
+			want:         `sample_count:11 sample_sum:0 schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 negative_span:<offset:0 length:5 > negative_delta:1 negative_delta:-1 negative_delta:2 negative_delta:-2 negative_delta:2 positive_span:<offset:0 length:5 > positive_delta:1 positive_delta:-1 positive_delta:2 positive_delta:-2 positive_delta:2 `,
+		},
+		{
+			name:          "wide zero bucket",
+			observations:  []float64{0, -1, -1.2, -1.4, -1.8, -2, 1, 1.2, 1.4, 1.8, 2},
+			factor:        1.2,
+			zeroThreshold: 1.4,
+			want:          `sample_count:11 sample_sum:0 schema:2 zero_threshold:1.4 zero_count:7 negative_span:<offset:4 length:1 > negative_delta:2 positive_span:<offset:4 length:1 > positive_delta:2 `,
+		},
+		{
+			name:         "NaN observation",
+			observations: []float64{0, 1, 1.2, 1.4, 1.8, 2, math.NaN()},
+			factor:       1.2,
+			want:         `sample_count:7 sample_sum:nan schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 positive_span:<offset:0 length:5 > positive_delta:1 positive_delta:-1 positive_delta:2 positive_delta:-2 positive_delta:2 `,
+		},
+		{
+			name:         "+Inf observation",
+			observations: []float64{0, 1, 1.2, 1.4, 1.8, 2, math.Inf(+1)},
+			factor:       1.2,
+			want:         `sample_count:7 sample_sum:inf schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 positive_span:<offset:0 length:5 > positive_span:<offset:4092 length:1 > positive_delta:1 positive_delta:-1 positive_delta:2 positive_delta:-2 positive_delta:2 positive_delta:-1 `,
+		},
+		{
+			name:         "-Inf observation",
+			observations: []float64{0, 1, 1.2, 1.4, 1.8, 2, math.Inf(-1)},
+			factor:       1.2,
+			want:         `sample_count:7 sample_sum:-inf schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 negative_span:<offset:4097 length:1 > negative_delta:1 positive_span:<offset:0 length:5 > positive_delta:1 positive_delta:-1 positive_delta:2 positive_delta:-2 positive_delta:2 `,
+		},
+		{
+			name:         "limited buckets but nothing triggered",
+			observations: []float64{0, 1, 1.2, 1.4, 1.8, 2},
+			factor:       1.2,
+			maxBuckets:   4,
+			want:         `sample_count:6 sample_sum:7.4 schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 positive_span:<offset:0 length:5 > positive_delta:1 positive_delta:-1 positive_delta:2 positive_delta:-2 positive_delta:2 `,
+		},
+		{
+			name:         "buckets limited by halving resolution",
+			observations: []float64{0, 1, 1.1, 1.2, 1.4, 1.8, 2, 3},
+			factor:       1.2,
+			maxBuckets:   4,
+			want:         `sample_count:8 sample_sum:11.5 schema:1 zero_threshold:2.938735877055719e-39 zero_count:1 positive_span:<offset:0 length:5 > positive_delta:1 positive_delta:2 positive_delta:-1 positive_delta:-2 positive_delta:1 `,
+		},
+		{
+			name:             "buckets limited by widening the zero bucket",
+			observations:     []float64{0, 1, 1.1, 1.2, 1.4, 1.8, 2, 3},
+			factor:           1.2,
+			maxBuckets:       4,
+			maxZeroThreshold: 1.2,
+			want:             `sample_count:8 sample_sum:11.5 schema:2 zero_threshold:1 zero_count:2 positive_span:<offset:1 length:7 > positive_delta:1 positive_delta:1 positive_delta:-2 positive_delta:2 positive_delta:-2 positive_delta:0 positive_delta:1 `,
+		},
+		{
+			name:             "buckets limited by widening the zero bucket twice",
+			observations:     []float64{0, 1, 1.1, 1.2, 1.4, 1.8, 2, 3, 4},
+			factor:           1.2,
+			maxBuckets:       4,
+			maxZeroThreshold: 1.2,
+			want:             `sample_count:9 sample_sum:15.5 schema:2 zero_threshold:1.189207115002721 zero_count:3 positive_span:<offset:2 length:7 > positive_delta:2 positive_delta:-2 positive_delta:2 positive_delta:-2 positive_delta:0 positive_delta:1 positive_delta:0 `,
+		},
+		{
+			name:             "buckets limited by reset",
+			observations:     []float64{0, 1, 1.1, 1.2, 1.4, 1.8, 2, 3, 4},
+			factor:           1.2,
+			maxBuckets:       4,
+			maxZeroThreshold: 1.2,
+			minResetDuration: 5 * time.Minute,
+			want:             `sample_count:2 sample_sum:7 schema:2 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:7 length:2 > positive_delta:1 positive_delta:0 `,
+		},
+		{
+			name:         "limited buckets but nothing triggered, negative observations",
+			observations: []float64{0, -1, -1.2, -1.4, -1.8, -2},
+			factor:       1.2,
+			maxBuckets:   4,
+			want:         `sample_count:6 sample_sum:-7.4 schema:2 zero_threshold:2.938735877055719e-39 zero_count:1 negative_span:<offset:0 length:5 > negative_delta:1 negative_delta:-1 negative_delta:2 negative_delta:-2 negative_delta:2 `,
+		},
+		{
+			name:         "buckets limited by halving resolution, negative observations",
+			observations: []float64{0, -1, -1.1, -1.2, -1.4, -1.8, -2, -3},
+			factor:       1.2,
+			maxBuckets:   4,
+			want:         `sample_count:8 sample_sum:-11.5 schema:1 zero_threshold:2.938735877055719e-39 zero_count:1 negative_span:<offset:0 length:5 > negative_delta:1 negative_delta:2 negative_delta:-1 negative_delta:-2 negative_delta:1 `,
+		},
+		{
+			name:             "buckets limited by widening the zero bucket, negative observations",
+			observations:     []float64{0, -1, -1.1, -1.2, -1.4, -1.8, -2, -3},
+			factor:           1.2,
+			maxBuckets:       4,
+			maxZeroThreshold: 1.2,
+			want:             `sample_count:8 sample_sum:-11.5 schema:2 zero_threshold:1 zero_count:2 negative_span:<offset:1 length:7 > negative_delta:1 negative_delta:1 negative_delta:-2 negative_delta:2 negative_delta:-2 negative_delta:0 negative_delta:1 `,
+		},
+		{
+			name:             "buckets limited by widening the zero bucket twice, negative observations",
+			observations:     []float64{0, -1, -1.1, -1.2, -1.4, -1.8, -2, -3, -4},
+			factor:           1.2,
+			maxBuckets:       4,
+			maxZeroThreshold: 1.2,
+			want:             `sample_count:9 sample_sum:-15.5 schema:2 zero_threshold:1.189207115002721 zero_count:3 negative_span:<offset:2 length:7 > negative_delta:2 negative_delta:-2 negative_delta:2 negative_delta:-2 negative_delta:0 negative_delta:1 negative_delta:0 `,
+		},
+		{
+			name:             "buckets limited by reset, negative observations",
+			observations:     []float64{0, -1, -1.1, -1.2, -1.4, -1.8, -2, -3, -4},
+			factor:           1.2,
+			maxBuckets:       4,
+			maxZeroThreshold: 1.2,
+			minResetDuration: 5 * time.Minute,
+			want:             `sample_count:2 sample_sum:-7 schema:2 zero_threshold:2.938735877055719e-39 zero_count:0 negative_span:<offset:7 length:2 > negative_delta:1 negative_delta:0 `,
+		},
+		{
+			name:             "buckets limited by halving resolution, then reset",
+			observations:     []float64{0, 1, 1.1, 1.2, 1.4, 1.8, 2, 5, 5.1, 3, 4},
+			factor:           1.2,
+			maxBuckets:       4,
+			minResetDuration: 9 * time.Minute,
+			want:             `sample_count:2 sample_sum:7 schema:2 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:7 length:2 > positive_delta:1 positive_delta:0 `,
+		},
+		{
+			name:             "buckets limited by widening the zero bucket, then reset",
+			observations:     []float64{0, 1, 1.1, 1.2, 1.4, 1.8, 2, 5, 5.1, 3, 4},
+			factor:           1.2,
+			maxBuckets:       4,
+			maxZeroThreshold: 1.2,
+			minResetDuration: 9 * time.Minute,
+			want:             `sample_count:2 sample_sum:7 schema:2 zero_threshold:2.938735877055719e-39 zero_count:0 positive_span:<offset:7 length:2 > positive_delta:1 positive_delta:0 `,
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.name, func(t *testing.T) {
+			his := NewHistogram(HistogramOpts{
+				Name:                            "name",
+				Help:                            "help",
+				NativeHistogramBucketFactor:     s.factor,
+				NativeHistogramZeroThreshold:    s.zeroThreshold,
+				NativeHistogramMaxBucketNumber:  s.maxBuckets,
+				NativeHistogramMinResetDuration: s.minResetDuration,
+				NativeHistogramMaxZeroThreshold: s.maxZeroThreshold,
+			})
+			ts := time.Now().Add(30 * time.Second)
+			now := func() time.Time {
+				return ts
+			}
+			his.(*histogram).now = now
+			for _, o := range s.observations {
+				his.Observe(o)
+				ts = ts.Add(time.Minute)
+			}
+			m := &dto.Metric{}
+			if err := his.Write(m); err != nil {
+				t.Fatal("unexpected error writing metric", err)
+			}
+			got := m.Histogram.String()
+			if s.want != got {
+				t.Errorf("want histogram %q, got %q", s.want, got)
+			}
+		})
+	}
+}
+
+func TestNativeHistogramConcurrency(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+	}
+
+	rand.Seed(42)
+
+	it := func(n uint32) bool {
+		mutations := int(n%1e4 + 1e4)
+		concLevel := int(n%5 + 1)
+		total := mutations * concLevel
+
+		var start, end sync.WaitGroup
+		start.Add(1)
+		end.Add(concLevel)
+
+		his := NewHistogram(HistogramOpts{
+			Name:                            "test_native_histogram",
+			Help:                            "This help is sparse.",
+			NativeHistogramBucketFactor:     1.05,
+			NativeHistogramZeroThreshold:    0.0000001,
+			NativeHistogramMaxBucketNumber:  50,
+			NativeHistogramMinResetDuration: time.Hour, // Comment out to test for totals below.
+			NativeHistogramMaxZeroThreshold: 0.001,
+		})
+
+		ts := time.Now().Add(30 * time.Second).Unix()
+		now := func() time.Time {
+			return time.Unix(atomic.LoadInt64(&ts), 0)
+		}
+		his.(*histogram).now = now
+
+		allVars := make([]float64, total)
+		var sampleSum float64
+		for i := 0; i < concLevel; i++ {
+			vals := make([]float64, mutations)
+			for j := 0; j < mutations; j++ {
+				v := rand.NormFloat64()
+				vals[j] = v
+				allVars[i*mutations+j] = v
+				sampleSum += v
+			}
+
+			go func(vals []float64) {
+				start.Wait()
+				for _, v := range vals {
+					// An observation every 1 to 10 seconds.
+					atomic.AddInt64(&ts, rand.Int63n(10)+1)
+					his.Observe(v)
+				}
+				end.Done()
+			}(vals)
+		}
+		sort.Float64s(allVars)
+		start.Done()
+		end.Wait()
+
+		m := &dto.Metric{}
+		his.Write(m)
+
+		// Uncomment these tests for totals only if you have disabled histogram resets above.
+		//
+		// if got, want := int(*m.Histogram.SampleCount), total; got != want {
+		// 	t.Errorf("got sample count %d, want %d", got, want)
+		// }
+		// if got, want := *m.Histogram.SampleSum, sampleSum; math.Abs((got-want)/want) > 0.001 {
+		// 	t.Errorf("got sample sum %f, want %f", got, want)
+		// }
+
+		sumBuckets := int(m.Histogram.GetZeroCount())
+		current := 0
+		for _, delta := range m.Histogram.GetNegativeDelta() {
+			current += int(delta)
+			if current < 0 {
+				t.Fatalf("negative bucket population negative: %d", current)
+			}
+			sumBuckets += current
+		}
+		current = 0
+		for _, delta := range m.Histogram.GetPositiveDelta() {
+			current += int(delta)
+			if current < 0 {
+				t.Fatalf("positive bucket population negative: %d", current)
+			}
+			sumBuckets += current
+		}
+		if got, want := sumBuckets, int(*m.Histogram.SampleCount); got != want {
+			t.Errorf("got bucket population sum %d, want %d", got, want)
+		}
+
+		return true
+	}
+
+	if err := quick.Check(it, nil); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestGetLe(t *testing.T) {
+	scenarios := []struct {
+		key    int
+		schema int32
+		want   float64
+	}{
+		{
+			key:    -1,
+			schema: -1,
+			want:   0.25,
+		},
+		{
+			key:    0,
+			schema: -1,
+			want:   1,
+		},
+		{
+			key:    1,
+			schema: -1,
+			want:   4,
+		},
+		{
+			key:    512,
+			schema: -1,
+			want:   math.MaxFloat64,
+		},
+		{
+			key:    513,
+			schema: -1,
+			want:   math.Inf(+1),
+		},
+		{
+			key:    -1,
+			schema: 0,
+			want:   0.5,
+		},
+		{
+			key:    0,
+			schema: 0,
+			want:   1,
+		},
+		{
+			key:    1,
+			schema: 0,
+			want:   2,
+		},
+		{
+			key:    1024,
+			schema: 0,
+			want:   math.MaxFloat64,
+		},
+		{
+			key:    1025,
+			schema: 0,
+			want:   math.Inf(+1),
+		},
+		{
+			key:    -1,
+			schema: 2,
+			want:   0.8408964152537144,
+		},
+		{
+			key:    0,
+			schema: 2,
+			want:   1,
+		},
+		{
+			key:    1,
+			schema: 2,
+			want:   1.189207115002721,
+		},
+		{
+			key:    4096,
+			schema: 2,
+			want:   math.MaxFloat64,
+		},
+		{
+			key:    4097,
+			schema: 2,
+			want:   math.Inf(+1),
+		},
+	}
+
+	for i, s := range scenarios {
+		got := getLe(s.key, s.schema)
+		if s.want != got {
+			t.Errorf("%d. key %d, schema %d, want upper bound of %g, got %g", i, s.key, s.schema, s.want, got)
+		}
+	}
+}

prometheus/internal/almost_equal.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2015 Björn Rabenstein
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+// The code in this package is copy/paste to avoid a dependency. Hence this file
+// carries the copyright of the original repo.
+// https://github.com/beorn7/floats
+package internal
+
+import (
+	"math"
+)
+
+// minNormalFloat64 is the smallest positive normal value of type float64.
+var minNormalFloat64 = math.Float64frombits(0x0010000000000000)
+
+// AlmostEqualFloat64 returns true if a and b are equal within a relative error
+// of epsilon. See http://floating-point-gui.de/errors/comparison/ for the
+// details of the applied method.
+func AlmostEqualFloat64(a, b, epsilon float64) bool {
+	if a == b {
+		return true
+	}
+	absA := math.Abs(a)
+	absB := math.Abs(b)
+	diff := math.Abs(a - b)
+	if a == 0 || b == 0 || absA+absB < minNormalFloat64 {
+		return diff < epsilon*minNormalFloat64
+	}
+	return diff/math.Min(absA+absB, math.MaxFloat64) < epsilon
+}
+
+// AlmostEqualFloat64s is the slice form of AlmostEqualFloat64.
+func AlmostEqualFloat64s(a, b []float64, epsilon float64) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if !AlmostEqualFloat64(a[i], b[i], epsilon) {
+			return false
+		}
+	}
+	return true
+}

prometheus/internal/difflib.go

@@ -0,0 +1,654 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// It provides tools to compare sequences of strings and generate textual diffs.
+//
+// Maintaining `GetUnifiedDiffString` here because original repository
+// (https://github.com/pmezard/go-difflib) is no loger maintained.
+package internal
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"strings"
+)
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func calculateRatio(matches, length int) float64 {
+	if length > 0 {
+		return 2.0 * float64(matches) / float64(length)
+	}
+	return 1.0
+}
+
+type Match struct {
+	A    int
+	B    int
+	Size int
+}
+
+type OpCode struct {
+	Tag byte
+	I1  int
+	I2  int
+	J1  int
+	J2  int
+}
+
+// SequenceMatcher compares sequence of strings. The basic
+// algorithm predates, and is a little fancier than, an algorithm
+// published in the late 1980's by Ratcliff and Obershelp under the
+// hyperbolic name "gestalt pattern matching".  The basic idea is to find
+// the longest contiguous matching subsequence that contains no "junk"
+// elements (R-O doesn't address junk).  The same idea is then applied
+// recursively to the pieces of the sequences to the left and to the right
+// of the matching subsequence.  This does not yield minimal edit
+// sequences, but does tend to yield matches that "look right" to people.
+//
+// SequenceMatcher tries to compute a "human-friendly diff" between two
+// sequences.  Unlike e.g. UNIX(tm) diff, the fundamental notion is the
+// longest *contiguous* & junk-free matching subsequence.  That's what
+// catches peoples' eyes.  The Windows(tm) windiff has another interesting
+// notion, pairing up elements that appear uniquely in each sequence.
+// That, and the method here, appear to yield more intuitive difference
+// reports than does diff.  This method appears to be the least vulnerable
+// to synching up on blocks of "junk lines", though (like blank lines in
+// ordinary text files, or maybe "<P>" lines in HTML files).  That may be
+// because this is the only method of the 3 that has a *concept* of
+// "junk" <wink>.
+//
+// Timing:  Basic R-O is cubic time worst case and quadratic time expected
+// case.  SequenceMatcher is quadratic time for the worst case and has
+// expected-case behavior dependent in a complicated way on how many
+// elements the sequences have in common; best case time is linear.
+type SequenceMatcher struct {
+	a              []string
+	b              []string
+	b2j            map[string][]int
+	IsJunk         func(string) bool
+	autoJunk       bool
+	bJunk          map[string]struct{}
+	matchingBlocks []Match
+	fullBCount     map[string]int
+	bPopular       map[string]struct{}
+	opCodes        []OpCode
+}
+
+func NewMatcher(a, b []string) *SequenceMatcher {
+	m := SequenceMatcher{autoJunk: true}
+	m.SetSeqs(a, b)
+	return &m
+}
+
+func NewMatcherWithJunk(a, b []string, autoJunk bool,
+	isJunk func(string) bool,
+) *SequenceMatcher {
+	m := SequenceMatcher{IsJunk: isJunk, autoJunk: autoJunk}
+	m.SetSeqs(a, b)
+	return &m
+}
+
+// Set two sequences to be compared.
+func (m *SequenceMatcher) SetSeqs(a, b []string) {
+	m.SetSeq1(a)
+	m.SetSeq2(b)
+}
+
+// Set the first sequence to be compared. The second sequence to be compared is
+// not changed.
+//
+// SequenceMatcher computes and caches detailed information about the second
+// sequence, so if you want to compare one sequence S against many sequences,
+// use .SetSeq2(s) once and call .SetSeq1(x) repeatedly for each of the other
+// sequences.
+//
+// See also SetSeqs() and SetSeq2().
+func (m *SequenceMatcher) SetSeq1(a []string) {
+	if &a == &m.a {
+		return
+	}
+	m.a = a
+	m.matchingBlocks = nil
+	m.opCodes = nil
+}
+
+// Set the second sequence to be compared. The first sequence to be compared is
+// not changed.
+func (m *SequenceMatcher) SetSeq2(b []string) {
+	if &b == &m.b {
+		return
+	}
+	m.b = b
+	m.matchingBlocks = nil
+	m.opCodes = nil
+	m.fullBCount = nil
+	m.chainB()
+}
+
+func (m *SequenceMatcher) chainB() {
+	// Populate line -> index mapping
+	b2j := map[string][]int{}
+	for i, s := range m.b {
+		indices := b2j[s]
+		indices = append(indices, i)
+		b2j[s] = indices
+	}
+
+	// Purge junk elements
+	m.bJunk = map[string]struct{}{}
+	if m.IsJunk != nil {
+		junk := m.bJunk
+		for s := range b2j {
+			if m.IsJunk(s) {
+				junk[s] = struct{}{}
+			}
+		}
+		for s := range junk {
+			delete(b2j, s)
+		}
+	}
+
+	// Purge remaining popular elements
+	popular := map[string]struct{}{}
+	n := len(m.b)
+	if m.autoJunk && n >= 200 {
+		ntest := n/100 + 1
+		for s, indices := range b2j {
+			if len(indices) > ntest {
+				popular[s] = struct{}{}
+			}
+		}
+		for s := range popular {
+			delete(b2j, s)
+		}
+	}
+	m.bPopular = popular
+	m.b2j = b2j
+}
+
+func (m *SequenceMatcher) isBJunk(s string) bool {
+	_, ok := m.bJunk[s]
+	return ok
+}
+
+// Find longest matching block in a[alo:ahi] and b[blo:bhi].
+//
+// If IsJunk is not defined:
+//
+// Return (i,j,k) such that a[i:i+k] is equal to b[j:j+k], where
+//
+//	alo <= i <= i+k <= ahi
+//	blo <= j <= j+k <= bhi
+//
+// and for all (i',j',k') meeting those conditions,
+//
+//	k >= k'
+//	i <= i'
+//	and if i == i', j <= j'
+//
+// In other words, of all maximal matching blocks, return one that
+// starts earliest in a, and of all those maximal matching blocks that
+// start earliest in a, return the one that starts earliest in b.
+//
+// If IsJunk is defined, first the longest matching block is
+// determined as above, but with the additional restriction that no
+// junk element appears in the block.  Then that block is extended as
+// far as possible by matching (only) junk elements on both sides.  So
+// the resulting block never matches on junk except as identical junk
+// happens to be adjacent to an "interesting" match.
+//
+// If no blocks match, return (alo, blo, 0).
+func (m *SequenceMatcher) findLongestMatch(alo, ahi, blo, bhi int) Match {
+	// CAUTION:  stripping common prefix or suffix would be incorrect.
+	// E.g.,
+	//    ab
+	//    acab
+	// Longest matching block is "ab", but if common prefix is
+	// stripped, it's "a" (tied with "b").  UNIX(tm) diff does so
+	// strip, so ends up claiming that ab is changed to acab by
+	// inserting "ca" in the middle.  That's minimal but unintuitive:
+	// "it's obvious" that someone inserted "ac" at the front.
+	// Windiff ends up at the same place as diff, but by pairing up
+	// the unique 'b's and then matching the first two 'a's.
+	besti, bestj, bestsize := alo, blo, 0
+
+	// find longest junk-free match
+	// during an iteration of the loop, j2len[j] = length of longest
+	// junk-free match ending with a[i-1] and b[j]
+	j2len := map[int]int{}
+	for i := alo; i != ahi; i++ {
+		// look at all instances of a[i] in b; note that because
+		// b2j has no junk keys, the loop is skipped if a[i] is junk
+		newj2len := map[int]int{}
+		for _, j := range m.b2j[m.a[i]] {
+			// a[i] matches b[j]
+			if j < blo {
+				continue
+			}
+			if j >= bhi {
+				break
+			}
+			k := j2len[j-1] + 1
+			newj2len[j] = k
+			if k > bestsize {
+				besti, bestj, bestsize = i-k+1, j-k+1, k
+			}
+		}
+		j2len = newj2len
+	}
+
+	// Extend the best by non-junk elements on each end.  In particular,
+	// "popular" non-junk elements aren't in b2j, which greatly speeds
+	// the inner loop above, but also means "the best" match so far
+	// doesn't contain any junk *or* popular non-junk elements.
+	for besti > alo && bestj > blo && !m.isBJunk(m.b[bestj-1]) &&
+		m.a[besti-1] == m.b[bestj-1] {
+		besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
+	}
+	for besti+bestsize < ahi && bestj+bestsize < bhi &&
+		!m.isBJunk(m.b[bestj+bestsize]) &&
+		m.a[besti+bestsize] == m.b[bestj+bestsize] {
+		bestsize++
+	}
+
+	// Now that we have a wholly interesting match (albeit possibly
+	// empty!), we may as well suck up the matching junk on each
+	// side of it too.  Can't think of a good reason not to, and it
+	// saves post-processing the (possibly considerable) expense of
+	// figuring out what to do with it.  In the case of an empty
+	// interesting match, this is clearly the right thing to do,
+	// because no other kind of match is possible in the regions.
+	for besti > alo && bestj > blo && m.isBJunk(m.b[bestj-1]) &&
+		m.a[besti-1] == m.b[bestj-1] {
+		besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
+	}
+	for besti+bestsize < ahi && bestj+bestsize < bhi &&
+		m.isBJunk(m.b[bestj+bestsize]) &&
+		m.a[besti+bestsize] == m.b[bestj+bestsize] {
+		bestsize++
+	}
+
+	return Match{A: besti, B: bestj, Size: bestsize}
+}
+
+// Return list of triples describing matching subsequences.
+//
+// Each triple is of the form (i, j, n), and means that
+// a[i:i+n] == b[j:j+n].  The triples are monotonically increasing in
+// i and in j. It's also guaranteed that if (i, j, n) and (i', j', n') are
+// adjacent triples in the list, and the second is not the last triple in the
+// list, then i+n != i' or j+n != j'. IOW, adjacent triples never describe
+// adjacent equal blocks.
+//
+// The last triple is a dummy, (len(a), len(b), 0), and is the only
+// triple with n==0.
+func (m *SequenceMatcher) GetMatchingBlocks() []Match {
+	if m.matchingBlocks != nil {
+		return m.matchingBlocks
+	}
+
+	var matchBlocks func(alo, ahi, blo, bhi int, matched []Match) []Match
+	matchBlocks = func(alo, ahi, blo, bhi int, matched []Match) []Match {
+		match := m.findLongestMatch(alo, ahi, blo, bhi)
+		i, j, k := match.A, match.B, match.Size
+		if match.Size > 0 {
+			if alo < i && blo < j {
+				matched = matchBlocks(alo, i, blo, j, matched)
+			}
+			matched = append(matched, match)
+			if i+k < ahi && j+k < bhi {
+				matched = matchBlocks(i+k, ahi, j+k, bhi, matched)
+			}
+		}
+		return matched
+	}
+	matched := matchBlocks(0, len(m.a), 0, len(m.b), nil)
+
+	// It's possible that we have adjacent equal blocks in the
+	// matching_blocks list now.
+	nonAdjacent := []Match{}
+	i1, j1, k1 := 0, 0, 0
+	for _, b := range matched {
+		// Is this block adjacent to i1, j1, k1?
+		i2, j2, k2 := b.A, b.B, b.Size
+		if i1+k1 == i2 && j1+k1 == j2 {
+			// Yes, so collapse them -- this just increases the length of
+			// the first block by the length of the second, and the first
+			// block so lengthened remains the block to compare against.
+			k1 += k2
+		} else {
+			// Not adjacent.  Remember the first block (k1==0 means it's
+			// the dummy we started with), and make the second block the
+			// new block to compare against.
+			if k1 > 0 {
+				nonAdjacent = append(nonAdjacent, Match{i1, j1, k1})
+			}
+			i1, j1, k1 = i2, j2, k2
+		}
+	}
+	if k1 > 0 {
+		nonAdjacent = append(nonAdjacent, Match{i1, j1, k1})
+	}
+
+	nonAdjacent = append(nonAdjacent, Match{len(m.a), len(m.b), 0})
+	m.matchingBlocks = nonAdjacent
+	return m.matchingBlocks
+}
+
+// Return list of 5-tuples describing how to turn a into b.
+//
+// Each tuple is of the form (tag, i1, i2, j1, j2).  The first tuple
+// has i1 == j1 == 0, and remaining tuples have i1 == the i2 from the
+// tuple preceding it, and likewise for j1 == the previous j2.
+//
+// The tags are characters, with these meanings:
+//
+// 'r' (replace):  a[i1:i2] should be replaced by b[j1:j2]
+//
+// 'd' (delete):   a[i1:i2] should be deleted, j1==j2 in this case.
+//
+// 'i' (insert):   b[j1:j2] should be inserted at a[i1:i1], i1==i2 in this case.
+//
+// 'e' (equal):    a[i1:i2] == b[j1:j2]
+func (m *SequenceMatcher) GetOpCodes() []OpCode {
+	if m.opCodes != nil {
+		return m.opCodes
+	}
+	i, j := 0, 0
+	matching := m.GetMatchingBlocks()
+	opCodes := make([]OpCode, 0, len(matching))
+	for _, m := range matching {
+		//  invariant:  we've pumped out correct diffs to change
+		//  a[:i] into b[:j], and the next matching block is
+		//  a[ai:ai+size] == b[bj:bj+size]. So we need to pump
+		//  out a diff to change a[i:ai] into b[j:bj], pump out
+		//  the matching block, and move (i,j) beyond the match
+		ai, bj, size := m.A, m.B, m.Size
+		tag := byte(0)
+		if i < ai && j < bj {
+			tag = 'r'
+		} else if i < ai {
+			tag = 'd'
+		} else if j < bj {
+			tag = 'i'
+		}
+		if tag > 0 {
+			opCodes = append(opCodes, OpCode{tag, i, ai, j, bj})
+		}
+		i, j = ai+size, bj+size
+		// the list of matching blocks is terminated by a
+		// sentinel with size 0
+		if size > 0 {
+			opCodes = append(opCodes, OpCode{'e', ai, i, bj, j})
+		}
+	}
+	m.opCodes = opCodes
+	return m.opCodes
+}
+
+// Isolate change clusters by eliminating ranges with no changes.
+//
+// Return a generator of groups with up to n lines of context.
+// Each group is in the same format as returned by GetOpCodes().
+func (m *SequenceMatcher) GetGroupedOpCodes(n int) [][]OpCode {
+	if n < 0 {
+		n = 3
+	}
+	codes := m.GetOpCodes()
+	if len(codes) == 0 {
+		codes = []OpCode{{'e', 0, 1, 0, 1}}
+	}
+	// Fixup leading and trailing groups if they show no changes.
+	if codes[0].Tag == 'e' {
+		c := codes[0]
+		i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
+		codes[0] = OpCode{c.Tag, max(i1, i2-n), i2, max(j1, j2-n), j2}
+	}
+	if codes[len(codes)-1].Tag == 'e' {
+		c := codes[len(codes)-1]
+		i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
+		codes[len(codes)-1] = OpCode{c.Tag, i1, min(i2, i1+n), j1, min(j2, j1+n)}
+	}
+	nn := n + n
+	groups := [][]OpCode{}
+	group := []OpCode{}
+	for _, c := range codes {
+		i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
+		// End the current group and start a new one whenever
+		// there is a large range with no changes.
+		if c.Tag == 'e' && i2-i1 > nn {
+			group = append(group, OpCode{
+				c.Tag, i1, min(i2, i1+n),
+				j1, min(j2, j1+n),
+			})
+			groups = append(groups, group)
+			group = []OpCode{}
+			i1, j1 = max(i1, i2-n), max(j1, j2-n)
+		}
+		group = append(group, OpCode{c.Tag, i1, i2, j1, j2})
+	}
+	if len(group) > 0 && !(len(group) == 1 && group[0].Tag == 'e') {
+		groups = append(groups, group)
+	}
+	return groups
+}
+
+// Return a measure of the sequences' similarity (float in [0,1]).
+//
+// Where T is the total number of elements in both sequences, and
+// M is the number of matches, this is 2.0*M / T.
+// Note that this is 1 if the sequences are identical, and 0 if
+// they have nothing in common.
+//
+// .Ratio() is expensive to compute if you haven't already computed
+// .GetMatchingBlocks() or .GetOpCodes(), in which case you may
+// want to try .QuickRatio() or .RealQuickRation() first to get an
+// upper bound.
+func (m *SequenceMatcher) Ratio() float64 {
+	matches := 0
+	for _, m := range m.GetMatchingBlocks() {
+		matches += m.Size
+	}
+	return calculateRatio(matches, len(m.a)+len(m.b))
+}
+
+// Return an upper bound on ratio() relatively quickly.
+//
+// This isn't defined beyond that it is an upper bound on .Ratio(), and
+// is faster to compute.
+func (m *SequenceMatcher) QuickRatio() float64 {
+	// viewing a and b as multisets, set matches to the cardinality
+	// of their intersection; this counts the number of matches
+	// without regard to order, so is clearly an upper bound
+	if m.fullBCount == nil {
+		m.fullBCount = map[string]int{}
+		for _, s := range m.b {
+			m.fullBCount[s]++
+		}
+	}
+
+	// avail[x] is the number of times x appears in 'b' less the
+	// number of times we've seen it in 'a' so far ... kinda
+	avail := map[string]int{}
+	matches := 0
+	for _, s := range m.a {
+		n, ok := avail[s]
+		if !ok {
+			n = m.fullBCount[s]
+		}
+		avail[s] = n - 1
+		if n > 0 {
+			matches++
+		}
+	}
+	return calculateRatio(matches, len(m.a)+len(m.b))
+}
+
+// Return an upper bound on ratio() very quickly.
+//
+// This isn't defined beyond that it is an upper bound on .Ratio(), and
+// is faster to compute than either .Ratio() or .QuickRatio().
+func (m *SequenceMatcher) RealQuickRatio() float64 {
+	la, lb := len(m.a), len(m.b)
+	return calculateRatio(min(la, lb), la+lb)
+}
+
+// Convert range to the "ed" format
+func formatRangeUnified(start, stop int) string {
+	// Per the diff spec at http://www.unix.org/single_unix_specification/
+	beginning := start + 1 // lines start numbering with one
+	length := stop - start
+	if length == 1 {
+		return fmt.Sprintf("%d", beginning)
+	}
+	if length == 0 {
+		beginning-- // empty ranges begin at line just before the range
+	}
+	return fmt.Sprintf("%d,%d", beginning, length)
+}
+
+// Unified diff parameters
+type UnifiedDiff struct {
+	A        []string // First sequence lines
+	FromFile string   // First file name
+	FromDate string   // First file time
+	B        []string // Second sequence lines
+	ToFile   string   // Second file name
+	ToDate   string   // Second file time
+	Eol      string   // Headers end of line, defaults to LF
+	Context  int      // Number of context lines
+}
+
+// Compare two sequences of lines; generate the delta as a unified diff.
+//
+// Unified diffs are a compact way of showing line changes and a few
+// lines of context.  The number of context lines is set by 'n' which
+// defaults to three.
+//
+// By default, the diff control lines (those with ---, +++, or @@) are
+// created with a trailing newline.  This is helpful so that inputs
+// created from file.readlines() result in diffs that are suitable for
+// file.writelines() since both the inputs and outputs have trailing
+// newlines.
+//
+// For inputs that do not have trailing newlines, set the lineterm
+// argument to "" so that the output will be uniformly newline free.
+//
+// The unidiff format normally has a header for filenames and modification
+// times.  Any or all of these may be specified using strings for
+// 'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.
+// The modification times are normally expressed in the ISO 8601 format.
+func WriteUnifiedDiff(writer io.Writer, diff UnifiedDiff) error {
+	buf := bufio.NewWriter(writer)
+	defer buf.Flush()
+	wf := func(format string, args ...interface{}) error {
+		_, err := buf.WriteString(fmt.Sprintf(format, args...))
+		return err
+	}
+	ws := func(s string) error {
+		_, err := buf.WriteString(s)
+		return err
+	}
+
+	if len(diff.Eol) == 0 {
+		diff.Eol = "\n"
+	}
+
+	started := false
+	m := NewMatcher(diff.A, diff.B)
+	for _, g := range m.GetGroupedOpCodes(diff.Context) {
+		if !started {
+			started = true
+			fromDate := ""
+			if len(diff.FromDate) > 0 {
+				fromDate = "\t" + diff.FromDate
+			}
+			toDate := ""
+			if len(diff.ToDate) > 0 {
+				toDate = "\t" + diff.ToDate
+			}
+			if diff.FromFile != "" || diff.ToFile != "" {
+				err := wf("--- %s%s%s", diff.FromFile, fromDate, diff.Eol)
+				if err != nil {
+					return err
+				}
+				err = wf("+++ %s%s%s", diff.ToFile, toDate, diff.Eol)
+				if err != nil {
+					return err
+				}
+			}
+		}
+		first, last := g[0], g[len(g)-1]
+		range1 := formatRangeUnified(first.I1, last.I2)
+		range2 := formatRangeUnified(first.J1, last.J2)
+		if err := wf("@@ -%s +%s @@%s", range1, range2, diff.Eol); err != nil {
+			return err
+		}
+		for _, c := range g {
+			i1, i2, j1, j2 := c.I1, c.I2, c.J1, c.J2
+			if c.Tag == 'e' {
+				for _, line := range diff.A[i1:i2] {
+					if err := ws(" " + line); err != nil {
+						return err
+					}
+				}
+				continue
+			}
+			if c.Tag == 'r' || c.Tag == 'd' {
+				for _, line := range diff.A[i1:i2] {
+					if err := ws("-" + line); err != nil {
+						return err
+					}
+				}
+			}
+			if c.Tag == 'r' || c.Tag == 'i' {
+				for _, line := range diff.B[j1:j2] {
+					if err := ws("+" + line); err != nil {
+						return err
+					}
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// Like WriteUnifiedDiff but returns the diff a string.
+func GetUnifiedDiffString(diff UnifiedDiff) (string, error) {
+	w := &bytes.Buffer{}
+	err := WriteUnifiedDiff(w, diff)
+	return w.String(), err
+}
+
+// Split a string on "\n" while preserving them. The output can be used
+// as input for UnifiedDiff and ContextDiff structures.
+func SplitLines(s string) []string {
+	lines := strings.SplitAfter(s, "\n")
+	lines[len(lines)-1] += "\n"
+	return lines
+}

prometheus/internal/difflib_test.go

@@ -0,0 +1,266 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package internal
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func assertAlmostEqual(t *testing.T, a, b float64, places int) {
+	if math.Abs(a-b) > math.Pow10(-places) {
+		t.Errorf("%.7f != %.7f", a, b)
+	}
+}
+
+func assertEqual(t *testing.T, a, b interface{}) {
+	if !reflect.DeepEqual(a, b) {
+		t.Errorf("%v != %v", a, b)
+	}
+}
+
+func splitChars(s string) []string {
+	chars := make([]string, 0, len(s))
+	// Assume ASCII inputs
+	for i := 0; i != len(s); i++ {
+		chars = append(chars, string(s[i]))
+	}
+	return chars
+}
+
+func TestSequenceMatcherRatio(t *testing.T) {
+	s := NewMatcher(splitChars("abcd"), splitChars("bcde"))
+	assertEqual(t, s.Ratio(), 0.75)
+	assertEqual(t, s.QuickRatio(), 0.75)
+	assertEqual(t, s.RealQuickRatio(), 1.0)
+}
+
+func TestGetOptCodes(t *testing.T) {
+	a := "qabxcd"
+	b := "abycdf"
+	s := NewMatcher(splitChars(a), splitChars(b))
+	w := &bytes.Buffer{}
+	for _, op := range s.GetOpCodes() {
+		fmt.Fprintf(w, "%s a[%d:%d], (%s) b[%d:%d] (%s)\n", string(op.Tag),
+			op.I1, op.I2, a[op.I1:op.I2], op.J1, op.J2, b[op.J1:op.J2])
+	}
+	result := w.String()
+	expected := `d a[0:1], (q) b[0:0] ()
+e a[1:3], (ab) b[0:2] (ab)
+r a[3:4], (x) b[2:3] (y)
+e a[4:6], (cd) b[3:5] (cd)
+i a[6:6], () b[5:6] (f)
+`
+	if expected != result {
+		t.Errorf("unexpected op codes: \n%s", result)
+	}
+}
+
+func TestGroupedOpCodes(t *testing.T) {
+	a := []string{}
+	for i := 0; i != 39; i++ {
+		a = append(a, fmt.Sprintf("%02d", i))
+	}
+	b := []string{}
+	b = append(b, a[:8]...)
+	b = append(b, " i")
+	b = append(b, a[8:19]...)
+	b = append(b, " x")
+	b = append(b, a[20:22]...)
+	b = append(b, a[27:34]...)
+	b = append(b, " y")
+	b = append(b, a[35:]...)
+	s := NewMatcher(a, b)
+	w := &bytes.Buffer{}
+	for _, g := range s.GetGroupedOpCodes(-1) {
+		fmt.Fprintf(w, "group\n")
+		for _, op := range g {
+			fmt.Fprintf(w, "  %s, %d, %d, %d, %d\n", string(op.Tag),
+				op.I1, op.I2, op.J1, op.J2)
+		}
+	}
+	result := w.String()
+	expected := `group
+  e, 5, 8, 5, 8
+  i, 8, 8, 8, 9
+  e, 8, 11, 9, 12
+group
+  e, 16, 19, 17, 20
+  r, 19, 20, 20, 21
+  e, 20, 22, 21, 23
+  d, 22, 27, 23, 23
+  e, 27, 30, 23, 26
+group
+  e, 31, 34, 27, 30
+  r, 34, 35, 30, 31
+  e, 35, 38, 31, 34
+`
+	if expected != result {
+		t.Errorf("unexpected op codes: \n%s", result)
+	}
+}
+
+func ExampleGetUnifiedDiffCode() {
+	a := `one
+two
+three
+four
+fmt.Printf("%s,%T",a,b)`
+	b := `zero
+one
+three
+four`
+	diff := UnifiedDiff{
+		A:        SplitLines(a),
+		B:        SplitLines(b),
+		FromFile: "Original",
+		FromDate: "2005-01-26 23:30:50",
+		ToFile:   "Current",
+		ToDate:   "2010-04-02 10:20:52",
+		Context:  3,
+	}
+	result, _ := GetUnifiedDiffString(diff)
+	fmt.Println(strings.ReplaceAll(result, "\t", " "))
+	// Output:
+	// --- Original 2005-01-26 23:30:50
+	// +++ Current 2010-04-02 10:20:52
+	// @@ -1,5 +1,4 @@
+	// +zero
+	//  one
+	// -two
+	//  three
+	//  four
+	// -fmt.Printf("%s,%T",a,b)
+}
+
+func rep(s string, count int) string {
+	return strings.Repeat(s, count)
+}
+
+func TestWithAsciiOneInsert(t *testing.T) {
+	sm := NewMatcher(splitChars(rep("b", 100)),
+		splitChars("a"+rep("b", 100)))
+	assertAlmostEqual(t, sm.Ratio(), 0.995, 3)
+	assertEqual(t, sm.GetOpCodes(),
+		[]OpCode{{'i', 0, 0, 0, 1}, {'e', 0, 100, 1, 101}})
+	assertEqual(t, len(sm.bPopular), 0)
+
+	sm = NewMatcher(splitChars(rep("b", 100)),
+		splitChars(rep("b", 50)+"a"+rep("b", 50)))
+	assertAlmostEqual(t, sm.Ratio(), 0.995, 3)
+	assertEqual(t, sm.GetOpCodes(),
+		[]OpCode{{'e', 0, 50, 0, 50}, {'i', 50, 50, 50, 51}, {'e', 50, 100, 51, 101}})
+	assertEqual(t, len(sm.bPopular), 0)
+}
+
+func TestWithAsciiOnDelete(t *testing.T) {
+	sm := NewMatcher(splitChars(rep("a", 40)+"c"+rep("b", 40)),
+		splitChars(rep("a", 40)+rep("b", 40)))
+	assertAlmostEqual(t, sm.Ratio(), 0.994, 3)
+	assertEqual(t, sm.GetOpCodes(),
+		[]OpCode{{'e', 0, 40, 0, 40}, {'d', 40, 41, 40, 40}, {'e', 41, 81, 40, 80}})
+}
+
+func TestWithAsciiBJunk(t *testing.T) {
+	isJunk := func(s string) bool {
+		return s == " "
+	}
+	sm := NewMatcherWithJunk(splitChars(rep("a", 40)+rep("b", 40)),
+		splitChars(rep("a", 44)+rep("b", 40)), true, isJunk)
+	assertEqual(t, sm.bJunk, map[string]struct{}{})
+
+	sm = NewMatcherWithJunk(splitChars(rep("a", 40)+rep("b", 40)),
+		splitChars(rep("a", 44)+rep("b", 40)+rep(" ", 20)), false, isJunk)
+	assertEqual(t, sm.bJunk, map[string]struct{}{" ": {}})
+
+	isJunk = func(s string) bool {
+		return s == " " || s == "b"
+	}
+	sm = NewMatcherWithJunk(splitChars(rep("a", 40)+rep("b", 40)),
+		splitChars(rep("a", 44)+rep("b", 40)+rep(" ", 20)), false, isJunk)
+	assertEqual(t, sm.bJunk, map[string]struct{}{" ": {}, "b": {}})
+}
+
+func TestSFBugsRatioForNullSeqn(t *testing.T) {
+	sm := NewMatcher(nil, nil)
+	assertEqual(t, sm.Ratio(), 1.0)
+	assertEqual(t, sm.QuickRatio(), 1.0)
+	assertEqual(t, sm.RealQuickRatio(), 1.0)
+}
+
+func TestSFBugsComparingEmptyLists(t *testing.T) {
+	groups := NewMatcher(nil, nil).GetGroupedOpCodes(-1)
+	assertEqual(t, len(groups), 0)
+	diff := UnifiedDiff{
+		FromFile: "Original",
+		ToFile:   "Current",
+		Context:  3,
+	}
+	result, err := GetUnifiedDiffString(diff)
+	assertEqual(t, err, nil)
+	assertEqual(t, result, "")
+}
+
+func TestOutputFormatRangeFormatUnified(t *testing.T) {
+	// Per the diff spec at http://www.unix.org/single_unix_specification/
+	//
+	// Each <range> field shall be of the form:
+	//   %1d", <beginning line number>  if the range contains exactly one line,
+	// and:
+	//  "%1d,%1d", <beginning line number>, <number of lines> otherwise.
+	// If a range is empty, its beginning line number shall be the number of
+	// the line just before the range, or 0 if the empty range starts the file.
+	fm := formatRangeUnified
+	assertEqual(t, fm(3, 3), "3,0")
+	assertEqual(t, fm(3, 4), "4")
+	assertEqual(t, fm(3, 5), "4,2")
+	assertEqual(t, fm(3, 6), "4,3")
+	assertEqual(t, fm(0, 0), "0,0")
+}
+
+func TestSplitLines(t *testing.T) {
+	allTests := []struct {
+		input string
+		want  []string
+	}{
+		{"foo", []string{"foo\n"}},
+		{"foo\nbar", []string{"foo\n", "bar\n"}},
+		{"foo\nbar\n", []string{"foo\n", "bar\n", "\n"}},
+	}
+	for _, test := range allTests {
+		assertEqual(t, SplitLines(test.input), test.want)
+	}
+}
+
+func benchmarkSplitLines(b *testing.B, count int) {
+	str := strings.Repeat("foo\n", count)
+
+	b.ResetTimer()
+
+	n := 0
+	for i := 0; i < b.N; i++ {
+		n += len(SplitLines(str))
+	}
+}
+
+func BenchmarkSplitLines100(b *testing.B) {
+	benchmarkSplitLines(b, 100)
+}
+
+func BenchmarkSplitLines10000(b *testing.B) {
+	benchmarkSplitLines(b, 10000)
+}

prometheus/internal/go_collector_options.go

@@ -0,0 +1,32 @@
+// Copyright 2021 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import "regexp"
+
+type GoCollectorRule struct {
+	Matcher *regexp.Regexp
+	Deny    bool
+}
+
+// GoCollectorOptions should not be used be directly by anything, except `collectors` package.
+// Use it via collectors package instead. See issue
+// https://git.internal/re/client_golang/issues/1030.
+//
+// This is internal, so external users only can use it via `collector.WithGoCollector*` methods
+type GoCollectorOptions struct {
+	DisableMemStatsLikeMetrics bool
+	RuntimeMetricSumForHist    map[string]string
+	RuntimeMetricRules         []GoCollectorRule
+}

prometheus/internal/go_runtime_metrics.go

@@ -61,9 +61,9 @@ func RuntimeMetricsToProm(d *metrics.Description) (string, string, string, bool)
 	// name has - replaced with _ and is concatenated with the unit and
 	// other data.
 	name = strings.ReplaceAll(name, "-", "_")
-	name = name + "_" + unit
+	name += "_" + unit
 	if d.Cumulative && d.Kind != metrics.KindFloat64Histogram {
-		name = name + "_total"
+		name += "_total"
 	}
 
 	valid := model.IsValidMetricName(model.LabelValue(namespace + "_" + subsystem + "_" + name))

prometheus/internal/metric.go

@@ -19,18 +19,34 @@ import (
 	dto "github.com/prometheus/client_model/go"
 )
 
-// metricSorter is a sortable slice of *dto.Metric.
+// LabelPairSorter implements sort.Interface. It is used to sort a slice of
-type metricSorter []*dto.Metric
+// dto.LabelPair pointers.
+type LabelPairSorter []*dto.LabelPair
 
-func (s metricSorter) Len() int {
+func (s LabelPairSorter) Len() int {
 	return len(s)
 }
 
-func (s metricSorter) Swap(i, j int) {
+func (s LabelPairSorter) Swap(i, j int) {
 	s[i], s[j] = s[j], s[i]
 }
 
-func (s metricSorter) Less(i, j int) bool {
+func (s LabelPairSorter) Less(i, j int) bool {
+	return s[i].GetName() < s[j].GetName()
+}
+
+// MetricSorter is a sortable slice of *dto.Metric.
+type MetricSorter []*dto.Metric
+
+func (s MetricSorter) Len() int {
+	return len(s)
+}
+
+func (s MetricSorter) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s MetricSorter) Less(i, j int) bool {
 	if len(s[i].Label) != len(s[j].Label) {
 		// This should not happen. The metrics are
 		// inconsistent. However, we have to deal with the fact, as
@@ -68,7 +84,7 @@ func (s metricSorter) Less(i, j int) bool {
 // the slice, with the contained Metrics sorted within each MetricFamily.
 func NormalizeMetricFamilies(metricFamiliesByName map[string]*dto.MetricFamily) []*dto.MetricFamily {
 	for _, mf := range metricFamiliesByName {
-		sort.Sort(metricSorter(mf.Metric))
+		sort.Sort(MetricSorter(mf.Metric))
 	}
 	names := make([]string, 0, len(metricFamiliesByName))
 	for name, mf := range metricFamiliesByName {

prometheus/labels.go

@@ -25,7 +25,8 @@ import (
 // Labels represents a collection of label name -> value mappings. This type is
 // commonly used with the With(Labels) and GetMetricWith(Labels) methods of
 // metric vector Collectors, e.g.:
-//     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
+//
+//	myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
 //
 // The other use-case is the specification of constant label pairs in Opts or to
 // create a Desc.
@@ -39,7 +40,7 @@ var errInconsistentCardinality = errors.New("inconsistent label cardinality")
 
 func makeInconsistentCardinalityError(fqName string, labels, labelValues []string) error {
 	return fmt.Errorf(
-		"%s: %q has %d variable labels named %q but %d values %q were provided",
+		"%w: %q has %d variable labels named %q but %d values %q were provided",
 		errInconsistentCardinality, fqName,
 		len(labels), labels,
 		len(labelValues), labelValues,
@@ -49,7 +50,7 @@ func makeInconsistentCardinalityError(fqName string, labels, labelValues []strin
 func validateValuesInLabels(labels Labels, expectedNumberOfValues int) error {
 	if len(labels) != expectedNumberOfValues {
 		return fmt.Errorf(
-			"%s: expected %d label values but got %d in %#v",
+			"%w: expected %d label values but got %d in %#v",
 			errInconsistentCardinality, expectedNumberOfValues,
 			len(labels), labels,
 		)
@@ -67,7 +68,7 @@ func validateValuesInLabels(labels Labels, expectedNumberOfValues int) error {
 func validateLabelValues(vals []string, expectedNumberOfValues int) error {
 	if len(vals) != expectedNumberOfValues {
 		return fmt.Errorf(
-			"%s: expected %d label values but got %d in %#v",
+			"%w: expected %d label values but got %d in %#v",
 			errInconsistentCardinality, expectedNumberOfValues,
 			len(vals), vals,
 		)

prometheus/metric.go

@@ -14,6 +14,9 @@
 package prometheus
 
 import (
+	"errors"
+	"math"
+	"sort"
 	"strings"
 	"time"
 
@@ -115,22 +118,6 @@ func BuildFQName(namespace, subsystem, name string) string {
 	return name
 }
 
-// labelPairSorter implements sort.Interface. It is used to sort a slice of
-// dto.LabelPair pointers.
-type labelPairSorter []*dto.LabelPair
-
-func (s labelPairSorter) Len() int {
-	return len(s)
-}
-
-func (s labelPairSorter) Swap(i, j int) {
-	s[i], s[j] = s[j], s[i]
-}
-
-func (s labelPairSorter) Less(i, j int) bool {
-	return s[i].GetName() < s[j].GetName()
-}
-
 type invalidMetric struct {
 	desc *Desc
 	err  error
@@ -174,3 +161,96 @@ func (m timestampedMetric) Write(pb *dto.Metric) error {
 func NewMetricWithTimestamp(t time.Time, m Metric) Metric {
 	return timestampedMetric{Metric: m, t: t}
 }
+
+type withExemplarsMetric struct {
+	Metric
+
+	exemplars []*dto.Exemplar
+}
+
+func (m *withExemplarsMetric) Write(pb *dto.Metric) error {
+	if err := m.Metric.Write(pb); err != nil {
+		return err
+	}
+
+	switch {
+	case pb.Counter != nil:
+		pb.Counter.Exemplar = m.exemplars[len(m.exemplars)-1]
+	case pb.Histogram != nil:
+		for _, e := range m.exemplars {
+			// pb.Histogram.Bucket are sorted by UpperBound.
+			i := sort.Search(len(pb.Histogram.Bucket), func(i int) bool {
+				return pb.Histogram.Bucket[i].GetUpperBound() >= e.GetValue()
+			})
+			if i < len(pb.Histogram.Bucket) {
+				pb.Histogram.Bucket[i].Exemplar = e
+			} else {
+				// The +Inf bucket should be explicitly added if there is an exemplar for it, similar to non-const histogram logic in https://git.internal/re/client_golang/blob/main/prometheus/histogram.go#L357-L365.
+				b := &dto.Bucket{
+					CumulativeCount: proto.Uint64(pb.Histogram.GetSampleCount()),
+					UpperBound:      proto.Float64(math.Inf(1)),
+					Exemplar:        e,
+				}
+				pb.Histogram.Bucket = append(pb.Histogram.Bucket, b)
+			}
+		}
+	default:
+		// TODO(bwplotka): Implement Gauge?
+		return errors.New("cannot inject exemplar into Gauge, Summary or Untyped")
+	}
+
+	return nil
+}
+
+// Exemplar is easier to use, user-facing representation of *dto.Exemplar.
+type Exemplar struct {
+	Value  float64
+	Labels Labels
+	// Optional.
+	// Default value (time.Time{}) indicates its empty, which should be
+	// understood as time.Now() time at the moment of creation of metric.
+	Timestamp time.Time
+}
+
+// NewMetricWithExemplars returns a new Metric wrapping the provided Metric with given
+// exemplars. Exemplars are validated.
+//
+// Only last applicable exemplar is injected from the list.
+// For example for Counter it means last exemplar is injected.
+// For Histogram, it means last applicable exemplar for each bucket is injected.
+//
+// NewMetricWithExemplars works best with MustNewConstMetric and
+// MustNewConstHistogram, see example.
+func NewMetricWithExemplars(m Metric, exemplars ...Exemplar) (Metric, error) {
+	if len(exemplars) == 0 {
+		return nil, errors.New("no exemplar was passed for NewMetricWithExemplars")
+	}
+
+	var (
+		now = time.Now()
+		exs = make([]*dto.Exemplar, len(exemplars))
+		err error
+	)
+	for i, e := range exemplars {
+		ts := e.Timestamp
+		if ts == (time.Time{}) {
+			ts = now
+		}
+		exs[i], err = newExemplar(e.Value, ts, e.Labels)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return &withExemplarsMetric{Metric: m, exemplars: exs}, nil
+}
+
+// MustNewMetricWithExemplars is a version of NewMetricWithExemplars that panics where
+// NewMetricWithExemplars would have returned an error.
+func MustNewMetricWithExemplars(m Metric, exemplars ...Exemplar) Metric {
+	ret, err := NewMetricWithExemplars(m, exemplars...)
+	if err != nil {
+		panic(err)
+	}
+	return ret
+}

prometheus/metric_test.go

@@ -13,7 +13,14 @@
 
 package prometheus
 
-import "testing"
+import (
+	"math"
+	"testing"
+
+	//nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility.
+	"github.com/golang/protobuf/proto"
+	dto "github.com/prometheus/client_model/go"
+)
 
 func TestBuildFQName(t *testing.T) {
 	scenarios := []struct{ namespace, subsystem, name, result string }{
@@ -33,3 +40,53 @@ func TestBuildFQName(t *testing.T) {
 		}
 	}
 }
+
+func TestWithExemplarsMetric(t *testing.T) {
+	t.Run("histogram", func(t *testing.T) {
+		// Create a constant histogram from values we got from a 3rd party telemetry system.
+		h := MustNewConstHistogram(
+			NewDesc("http_request_duration_seconds", "A histogram of the HTTP request durations.", nil, nil),
+			4711, 403.34,
+			// Four buckets, but we expect five as the +Inf bucket will be created if we see value outside of those buckets.
+			map[float64]uint64{25: 121, 50: 2403, 100: 3221, 200: 4233},
+		)
+
+		m := &withExemplarsMetric{Metric: h, exemplars: []*dto.Exemplar{
+			{Value: proto.Float64(2000.0)}, // Unordered exemplars.
+			{Value: proto.Float64(500.0)},
+			{Value: proto.Float64(42.0)},
+			{Value: proto.Float64(157.0)},
+			{Value: proto.Float64(100.0)},
+			{Value: proto.Float64(89.0)},
+			{Value: proto.Float64(24.0)},
+			{Value: proto.Float64(25.1)},
+		}}
+		metric := dto.Metric{}
+		if err := m.Write(&metric); err != nil {
+			t.Fatal(err)
+		}
+		if want, got := 5, len(metric.GetHistogram().Bucket); want != got {
+			t.Errorf("want %v, got %v", want, got)
+		}
+
+		expectedExemplarVals := []float64{24.0, 25.1, 89.0, 157.0, 500.0}
+		for i, b := range metric.GetHistogram().Bucket {
+			if b.Exemplar == nil {
+				t.Errorf("Expected exemplar for bucket %v, got nil", i)
+			}
+			if want, got := expectedExemplarVals[i], *metric.GetHistogram().Bucket[i].Exemplar.Value; want != got {
+				t.Errorf("%v: want %v, got %v", i, want, got)
+			}
+		}
+
+		infBucket := metric.GetHistogram().Bucket[len(metric.GetHistogram().Bucket)-1]
+
+		if want, got := math.Inf(1), infBucket.GetUpperBound(); want != got {
+			t.Errorf("want %v, got %v", want, got)
+		}
+
+		if want, got := uint64(4711), infBucket.GetCumulativeCount(); want != got {
+			t.Errorf("want %v, got %v", want, got)
+		}
+	})
+}

prometheus/num_threads.go

@@ -0,0 +1,25 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !js || wasm
+// +build !js wasm
+
+package prometheus
+
+import "runtime"
+
+// getRuntimeNumThreads returns the number of open OS threads.
+func getRuntimeNumThreads() float64 {
+	n, _ := runtime.ThreadCreateProfile(nil)
+	return float64(n)
+}

prometheus/num_threads_gopherjs.go

@@ -0,0 +1,22 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build js && !wasm
+// +build js,!wasm
+
+package prometheus
+
+// getRuntimeNumThreads returns the number of open OS threads.
+func getRuntimeNumThreads() float64 {
+	return 1
+}

prometheus/observer.go

@@ -58,7 +58,7 @@ type ObserverVec interface {
 // current time as timestamp, and the provided Labels. Empty Labels will lead to
 // a valid (label-less) exemplar. But if Labels is nil, the current exemplar is
 // left in place. ObserveWithExemplar panics if any of the provided labels are
-// invalid or if the provided labels contain more than 64 runes in total.
+// invalid or if the provided labels contain more than 128 runes in total.
 type ExemplarObserver interface {
 	ObserveWithExemplar(value float64, exemplar Labels)
 }

prometheus/process_collector.go

@@ -16,7 +16,6 @@ package prometheus
 import (
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"strconv"
 	"strings"
@@ -104,8 +103,7 @@ func NewProcessCollector(opts ProcessCollectorOpts) Collector {
 	}
 
 	if opts.PidFn == nil {
-		pid := os.Getpid()
+		c.pidFn = getPIDFn()
-		c.pidFn = func() (int, error) { return pid, nil }
 	} else {
 		c.pidFn = opts.PidFn
 	}
@@ -152,13 +150,13 @@ func (c *processCollector) reportError(ch chan<- Metric, desc *Desc, err error)
 // It is meant to be used for the PidFn field in ProcessCollectorOpts.
 func NewPidFileFn(pidFilePath string) func() (int, error) {
 	return func() (int, error) {
-		content, err := ioutil.ReadFile(pidFilePath)
+		content, err := os.ReadFile(pidFilePath)
 		if err != nil {
-			return 0, fmt.Errorf("can't read pid file %q: %+v", pidFilePath, err)
+			return 0, fmt.Errorf("can't read pid file %q: %w", pidFilePath, err)
 		}
 		pid, err := strconv.Atoi(strings.TrimSpace(string(content)))
 		if err != nil {
-			return 0, fmt.Errorf("can't parse pid file %q: %+v", pidFilePath, err)
+			return 0, fmt.Errorf("can't parse pid file %q: %w", pidFilePath, err)
 		}
 
 		return pid, nil

prometheus/process_collector_js.go

@@ -1,4 +1,4 @@
-// Copyright 2021 The Prometheus Authors
+// Copyright 2019 The Prometheus Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -11,21 +11,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.15
+//go:build js
-// +build go1.15
+// +build js
 
-package collectors
+package prometheus
 
-import (
+func canCollectProcess() bool {
-	"database/sql"
+	return false
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-func (c *dbStatsCollector) describeNewInGo115(ch chan<- *prometheus.Desc) {
-	ch <- c.maxIdleTimeClosed
 }
 
-func (c *dbStatsCollector) collectNewInGo115(ch chan<- prometheus.Metric, stats sql.DBStats) {
+func (c *processCollector) processCollect(ch chan<- Metric) {
-	ch <- prometheus.MustNewConstMetric(c.maxIdleTimeClosed, prometheus.CounterValue, float64(stats.MaxIdleTimeClosed))
+	// noop on this platform
+	return
 }

prometheus/process_collector_other.go

@@ -11,8 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !windows
+//go:build !windows && !js
-// +build !windows
+// +build !windows,!js
 
 package prometheus
 

prometheus/promauto/auto.go

@@ -14,114 +14,114 @@
 // Package promauto provides alternative constructors for the fundamental
 // Prometheus metric types and their …Vec and …Func variants. The difference to
 // their counterparts in the prometheus package is that the promauto
-// constructors return Collectors that are already registered with a
+// constructors register the Collectors with a registry before returning them.
-// registry. There are two sets of constructors. The constructors in the first
+// There are two sets of constructors. The constructors in the first set are
-// set are top-level functions, while the constructors in the other set are
+// top-level functions, while the constructors in the other set are methods of
-// methods of the Factory type. The top-level function return Collectors
+// the Factory type. The top-level function return Collectors registered with
-// registered with the global registry (prometheus.DefaultRegisterer), while the
+// the global registry (prometheus.DefaultRegisterer), while the methods return
-// methods return Collectors registered with the registry the Factory was
+// Collectors registered with the registry the Factory was constructed with. All
-// constructed with. All constructors panic if the registration fails.
+// constructors panic if the registration fails.
 //
 // The following example is a complete program to create a histogram of normally
 // distributed random numbers from the math/rand package:
 //
-//      package main
+//	package main
 //
-//      import (
+//	import (
-//              "math/rand"
+//	        "math/rand"
-//              "net/http"
+//	        "net/http"
 //
-//              "github.com/prometheus/client_golang/prometheus"
+//	        "git.internal/re/client_golang/prometheus"
-//              "github.com/prometheus/client_golang/prometheus/promauto"
+//	        "git.internal/re/client_golang/prometheus/promauto"
-//              "github.com/prometheus/client_golang/prometheus/promhttp"
+//	        "git.internal/re/client_golang/prometheus/promhttp"
-//      )
+//	)
 //
-//      var histogram = promauto.NewHistogram(prometheus.HistogramOpts{
+//	var histogram = promauto.NewHistogram(prometheus.HistogramOpts{
-//              Name:    "random_numbers",
+//	        Name:    "random_numbers",
-//              Help:    "A histogram of normally distributed random numbers.",
+//	        Help:    "A histogram of normally distributed random numbers.",
-//              Buckets: prometheus.LinearBuckets(-3, .1, 61),
+//	        Buckets: prometheus.LinearBuckets(-3, .1, 61),
-//      })
+//	})
 //
-//      func Random() {
+//	func Random() {
-//              for {
+//	        for {
-//                      histogram.Observe(rand.NormFloat64())
+//	                histogram.Observe(rand.NormFloat64())
-//              }
+//	        }
-//      }
+//	}
 //
-//      func main() {
+//	func main() {
-//              go Random()
+//	        go Random()
-//              http.Handle("/metrics", promhttp.Handler())
+//	        http.Handle("/metrics", promhttp.Handler())
-//              http.ListenAndServe(":1971", nil)
+//	        http.ListenAndServe(":1971", nil)
-//      }
+//	}
 //
 // Prometheus's version of a minimal hello-world program:
 //
-//      package main
+//	package main
 //
-//      import (
+//	import (
-//      	"fmt"
+//		"fmt"
-//      	"net/http"
+//		"net/http"
 //
-//      	"github.com/prometheus/client_golang/prometheus"
+//		"git.internal/re/client_golang/prometheus"
-//      	"github.com/prometheus/client_golang/prometheus/promauto"
+//		"git.internal/re/client_golang/prometheus/promauto"
-//      	"github.com/prometheus/client_golang/prometheus/promhttp"
+//		"git.internal/re/client_golang/prometheus/promhttp"
-//      )
+//	)
 //
-//      func main() {
+//	func main() {
-//      	http.Handle("/", promhttp.InstrumentHandlerCounter(
+//		http.Handle("/", promhttp.InstrumentHandlerCounter(
-//      		promauto.NewCounterVec(
+//			promauto.NewCounterVec(
-//      			prometheus.CounterOpts{
+//				prometheus.CounterOpts{
-//      				Name: "hello_requests_total",
+//					Name: "hello_requests_total",
-//      				Help: "Total number of hello-world requests by HTTP code.",
+//					Help: "Total number of hello-world requests by HTTP code.",
-//      			},
+//				},
-//      			[]string{"code"},
+//				[]string{"code"},
-//      		),
+//			),
-//      		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+//			http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-//      			fmt.Fprint(w, "Hello, world!")
+//				fmt.Fprint(w, "Hello, world!")
-//      		}),
+//			}),
-//      	))
+//		))
-//      	http.Handle("/metrics", promhttp.Handler())
+//		http.Handle("/metrics", promhttp.Handler())
-//      	http.ListenAndServe(":1971", nil)
+//		http.ListenAndServe(":1971", nil)
-//      }
+//	}
 //
 // A Factory is created with the With(prometheus.Registerer) function, which
 // enables two usage pattern. With(prometheus.Registerer) can be called once per
 // line:
 //
-//        var (
+//	var (
-//        	reg           = prometheus.NewRegistry()
+//		reg           = prometheus.NewRegistry()
-//        	randomNumbers = promauto.With(reg).NewHistogram(prometheus.HistogramOpts{
+//		randomNumbers = promauto.With(reg).NewHistogram(prometheus.HistogramOpts{
-//        		Name:    "random_numbers",
+//			Name:    "random_numbers",
-//        		Help:    "A histogram of normally distributed random numbers.",
+//			Help:    "A histogram of normally distributed random numbers.",
-//        		Buckets: prometheus.LinearBuckets(-3, .1, 61),
+//			Buckets: prometheus.LinearBuckets(-3, .1, 61),
-//        	})
+//		})
-//        	requestCount = promauto.With(reg).NewCounterVec(
+//		requestCount = promauto.With(reg).NewCounterVec(
-//        		prometheus.CounterOpts{
+//			prometheus.CounterOpts{
-//        			Name: "http_requests_total",
+//				Name: "http_requests_total",
-//        			Help: "Total number of HTTP requests by status code and method.",
+//				Help: "Total number of HTTP requests by status code and method.",
-//        		},
+//			},
-//        		[]string{"code", "method"},
+//			[]string{"code", "method"},
-//        	)
+//		)
-//        )
+//	)
 //
 // Or it can be used to create a Factory once to be used multiple times:
 //
-//        var (
+//	var (
-//        	reg           = prometheus.NewRegistry()
+//		reg           = prometheus.NewRegistry()
-//        	factory       = promauto.With(reg)
+//		factory       = promauto.With(reg)
-//        	randomNumbers = factory.NewHistogram(prometheus.HistogramOpts{
+//		randomNumbers = factory.NewHistogram(prometheus.HistogramOpts{
-//        		Name:    "random_numbers",
+//			Name:    "random_numbers",
-//        		Help:    "A histogram of normally distributed random numbers.",
+//			Help:    "A histogram of normally distributed random numbers.",
-//        		Buckets: prometheus.LinearBuckets(-3, .1, 61),
+//			Buckets: prometheus.LinearBuckets(-3, .1, 61),
-//        	})
+//		})
-//        	requestCount = factory.NewCounterVec(
+//		requestCount = factory.NewCounterVec(
-//        		prometheus.CounterOpts{
+//			prometheus.CounterOpts{
-//        			Name: "http_requests_total",
+//				Name: "http_requests_total",
-//        			Help: "Total number of HTTP requests by status code and method.",
+//				Help: "Total number of HTTP requests by status code and method.",
-//        		},
+//			},
-//        		[]string{"code", "method"},
+//			[]string{"code", "method"},
-//        	)
+//		)
-//        )
+//	)
 //
 // This appears very handy. So why are these constructors locked away in a
 // separate package?
@@ -159,7 +159,7 @@
 // Enjoy promauto responsibly!
 package promauto
 
-import "github.com/prometheus/client_golang/prometheus"
+import "git.internal/re/client_golang/prometheus"
 
 // NewCounter works like the function of the same name in the prometheus package
 // but it automatically registers the Counter with the

prometheus/promauto/auto_test.go

@@ -16,7 +16,7 @@ package promauto
 import (
 	"testing"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 func TestNil(t *testing.T) {

prometheus/promhttp/delegator.go

@@ -76,16 +76,19 @@ func (r *responseWriterDelegator) Write(b []byte) (int, error) {
 	return n, err
 }
 
-type closeNotifierDelegator struct{ *responseWriterDelegator }
+type (
-type flusherDelegator struct{ *responseWriterDelegator }
+	closeNotifierDelegator struct{ *responseWriterDelegator }
-type hijackerDelegator struct{ *responseWriterDelegator }
+	flusherDelegator       struct{ *responseWriterDelegator }
-type readerFromDelegator struct{ *responseWriterDelegator }
+	hijackerDelegator      struct{ *responseWriterDelegator }
-type pusherDelegator struct{ *responseWriterDelegator }
+	readerFromDelegator    struct{ *responseWriterDelegator }
+	pusherDelegator        struct{ *responseWriterDelegator }
+)
 
 func (d closeNotifierDelegator) CloseNotify() <-chan bool {
 	//nolint:staticcheck // Ignore SA1019. http.CloseNotifier is deprecated but we keep it here to not break existing users.
 	return d.ResponseWriter.(http.CloseNotifier).CloseNotify()
 }
+
 func (d flusherDelegator) Flush() {
 	// If applicable, call WriteHeader here so that observeWriteHeader is
 	// handled appropriately.
@@ -94,9 +97,11 @@ func (d flusherDelegator) Flush() {
 	}
 	d.ResponseWriter.(http.Flusher).Flush()
 }
+
 func (d hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) {
 	return d.ResponseWriter.(http.Hijacker).Hijack()
 }
+
 func (d readerFromDelegator) ReadFrom(re io.Reader) (int64, error) {
 	// If applicable, call WriteHeader here so that observeWriteHeader is
 	// handled appropriately.
@@ -107,6 +112,7 @@ func (d readerFromDelegator) ReadFrom(re io.Reader) (int64, error) {
 	d.written += n
 	return n, err
 }
+
 func (d pusherDelegator) Push(target string, opts *http.PushOptions) error {
 	return d.ResponseWriter.(http.Pusher).Push(target, opts)
 }
@@ -261,7 +267,7 @@ func init() {
 			http.Flusher
 		}{d, pusherDelegator{d}, hijackerDelegator{d}, flusherDelegator{d}}
 	}
-	pickDelegator[pusher+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { //23
+	pickDelegator[pusher+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 23
 		return struct {
 			*responseWriterDelegator
 			http.Pusher

prometheus/promhttp/http.go

@@ -33,6 +33,7 @@ package promhttp
 
 import (
 	"compress/gzip"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -42,7 +43,7 @@ import (
 
 	"github.com/prometheus/common/expfmt"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 const (
@@ -84,6 +85,13 @@ func Handler() http.Handler {
 // instrumentation. Use the InstrumentMetricHandler function to apply the same
 // kind of instrumentation as it is used by the Handler function.
 func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
+	return HandlerForTransactional(prometheus.ToTransactionalGatherer(reg), opts)
+}
+
+// HandlerForTransactional is like HandlerFor, but it uses transactional gather, which
+// can safely change in-place returned *dto.MetricFamily before call to `Gather` and after
+// call to `done` of that `Gather`.
+func HandlerForTransactional(reg prometheus.TransactionalGatherer, opts HandlerOpts) http.Handler {
 	var (
 		inFlightSem chan struct{}
 		errCnt      = prometheus.NewCounterVec(
@@ -103,7 +111,8 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
 		errCnt.WithLabelValues("gathering")
 		errCnt.WithLabelValues("encoding")
 		if err := opts.Registry.Register(errCnt); err != nil {
-			if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
+			are := &prometheus.AlreadyRegisteredError{}
+			if errors.As(err, are) {
 				errCnt = are.ExistingCollector.(*prometheus.CounterVec)
 			} else {
 				panic(err)
@@ -123,7 +132,8 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
 				return
 			}
 		}
-		mfs, err := reg.Gather()
+		mfs, done, err := reg.Gather()
+		defer done()
 		if err != nil {
 			if opts.ErrorLog != nil {
 				opts.ErrorLog.Println("error gathering metrics:", err)
@@ -242,7 +252,8 @@ func InstrumentMetricHandler(reg prometheus.Registerer, handler http.Handler) ht
 	cnt.WithLabelValues("500")
 	cnt.WithLabelValues("503")
 	if err := reg.Register(cnt); err != nil {
-		if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
+		are := &prometheus.AlreadyRegisteredError{}
+		if errors.As(err, are) {
 			cnt = are.ExistingCollector.(*prometheus.CounterVec)
 		} else {
 			panic(err)
@@ -254,7 +265,8 @@ func InstrumentMetricHandler(reg prometheus.Registerer, handler http.Handler) ht
 		Help: "Current number of scrapes being served.",
 	})
 	if err := reg.Register(gge); err != nil {
-		if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
+		are := &prometheus.AlreadyRegisteredError{}
+		if errors.As(err, are) {
 			gge = are.ExistingCollector.(prometheus.Gauge)
 		} else {
 			panic(err)

prometheus/promhttp/http_test.go

@@ -16,6 +16,7 @@ package promhttp
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"log"
 	"net/http"
 	"net/http/httptest"
@@ -23,7 +24,9 @@ import (
 	"testing"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+
+	"git.internal/re/client_golang/prometheus"
 )
 
 type errorCollector struct{}
@@ -56,8 +59,19 @@ func (b blockingCollector) Collect(ch chan<- prometheus.Metric) {
 	<-b.Block
 }
 
-func TestHandlerErrorHandling(t *testing.T) {
+type mockTransactionGatherer struct {
+	g             prometheus.Gatherer
+	gatherInvoked int
+	doneInvoked   int
+}
 
+func (g *mockTransactionGatherer) Gather() (_ []*dto.MetricFamily, done func(), err error) {
+	g.gatherInvoked++
+	mfs, err := g.g.Gather()
+	return mfs, func() { g.doneInvoked++ }, err
+}
+
+func TestHandlerErrorHandling(t *testing.T) {
 	// Create a registry that collects a MetricFamily with two elements,
 	// another with one, and reports an error. Further down, we'll use the
 	// same registry in the HandlerOpts.
@@ -90,21 +104,30 @@ func TestHandlerErrorHandling(t *testing.T) {
 	request, _ := http.NewRequest("GET", "/", nil)
 	request.Header.Add("Accept", "test/plain")
 
-	errorHandler := HandlerFor(reg, HandlerOpts{
+	mReg := &mockTransactionGatherer{g: reg}
+	errorHandler := HandlerForTransactional(mReg, HandlerOpts{
 		ErrorLog:      logger,
 		ErrorHandling: HTTPErrorOnError,
 		Registry:      reg,
 	})
-	continueHandler := HandlerFor(reg, HandlerOpts{
+	continueHandler := HandlerForTransactional(mReg, HandlerOpts{
 		ErrorLog:      logger,
 		ErrorHandling: ContinueOnError,
 		Registry:      reg,
 	})
-	panicHandler := HandlerFor(reg, HandlerOpts{
+	panicHandler := HandlerForTransactional(mReg, HandlerOpts{
 		ErrorLog:      logger,
 		ErrorHandling: PanicOnError,
 		Registry:      reg,
 	})
+	// Expect gatherer not touched.
+	if got := mReg.gatherInvoked; got != 0 {
+		t.Fatalf("unexpected number of gather invokes, want 0, got %d", got)
+	}
+	if got := mReg.doneInvoked; got != 0 {
+		t.Fatalf("unexpected number of done invokes, want 0, got %d", got)
+	}
+
 	wantMsg := `error gathering metrics: error collecting metric Desc{fqName: "invalid_metric", help: "not helpful", constLabels: {}, variableLabels: []}: collect error
 `
 	wantErrorBody := `An error has occurred while serving metrics:
@@ -140,25 +163,39 @@ the_count 0
 `
 
 	errorHandler.ServeHTTP(writer, request)
+	if got := mReg.gatherInvoked; got != 1 {
+		t.Fatalf("unexpected number of gather invokes, want 1, got %d", got)
+	}
+	if got := mReg.doneInvoked; got != 1 {
+		t.Fatalf("unexpected number of done invokes, want 1, got %d", got)
+	}
 	if got, want := writer.Code, http.StatusInternalServerError; got != want {
 		t.Errorf("got HTTP status code %d, want %d", got, want)
 	}
-	if got := logBuf.String(); got != wantMsg {
+	if got, want := logBuf.String(), wantMsg; got != want {
-		t.Errorf("got log message:\n%s\nwant log message:\n%s\n", got, wantMsg)
+		t.Errorf("got log buf %q, want %q", got, want)
 	}
-	if got := writer.Body.String(); got != wantErrorBody {
+	if got, want := writer.Body.String(), wantErrorBody; got != want {
-		t.Errorf("got body:\n%s\nwant body:\n%s\n", got, wantErrorBody)
+		t.Errorf("got body %q, want %q", got, want)
 	}
+
 	logBuf.Reset()
 	writer.Body.Reset()
 	writer.Code = http.StatusOK
 
 	continueHandler.ServeHTTP(writer, request)
+
+	if got := mReg.gatherInvoked; got != 2 {
+		t.Fatalf("unexpected number of gather invokes, want 2, got %d", got)
+	}
+	if got := mReg.doneInvoked; got != 2 {
+		t.Fatalf("unexpected number of done invokes, want 2, got %d", got)
+	}
 	if got, want := writer.Code, http.StatusOK; got != want {
 		t.Errorf("got HTTP status code %d, want %d", got, want)
 	}
-	if got := logBuf.String(); got != wantMsg {
+	if got, want := logBuf.String(), wantMsg; got != want {
-		t.Errorf("got log message %q, want %q", got, wantMsg)
+		t.Errorf("got log buf %q, want %q", got, want)
 	}
 	if got := writer.Body.String(); got != wantOKBody1 && got != wantOKBody2 {
 		t.Errorf("got body %q, want either %q or %q", got, wantOKBody1, wantOKBody2)
@@ -168,20 +205,34 @@ the_count 0
 		if err := recover(); err == nil {
 			t.Error("expected panic from panicHandler")
 		}
+		if got := mReg.gatherInvoked; got != 3 {
+			t.Fatalf("unexpected number of gather invokes, want 3, got %d", got)
+		}
+		if got := mReg.doneInvoked; got != 3 {
+			t.Fatalf("unexpected number of done invokes, want 3, got %d", got)
+		}
 	}()
 	panicHandler.ServeHTTP(writer, request)
 }
 
 func TestInstrumentMetricHandler(t *testing.T) {
 	reg := prometheus.NewRegistry()
-	handler := InstrumentMetricHandler(reg, HandlerFor(reg, HandlerOpts{}))
+	mReg := &mockTransactionGatherer{g: reg}
+	handler := InstrumentMetricHandler(reg, HandlerForTransactional(mReg, HandlerOpts{}))
 	// Do it again to test idempotency.
-	InstrumentMetricHandler(reg, HandlerFor(reg, HandlerOpts{}))
+	InstrumentMetricHandler(reg, HandlerForTransactional(mReg, HandlerOpts{}))
 	writer := httptest.NewRecorder()
 	request, _ := http.NewRequest("GET", "/", nil)
 	request.Header.Add("Accept", "test/plain")
 
 	handler.ServeHTTP(writer, request)
+	if got := mReg.gatherInvoked; got != 1 {
+		t.Fatalf("unexpected number of gather invokes, want 1, got %d", got)
+	}
+	if got := mReg.doneInvoked; got != 1 {
+		t.Fatalf("unexpected number of done invokes, want 1, got %d", got)
+	}
+
 	if got, want := writer.Code, http.StatusOK; got != want {
 		t.Errorf("got HTTP status code %d, want %d", got, want)
 	}
@@ -195,19 +246,28 @@ func TestInstrumentMetricHandler(t *testing.T) {
 		t.Errorf("got body %q, does not contain %q", got, want)
 	}
 
-	writer.Body.Reset()
+	for i := 0; i < 100; i++ {
-	handler.ServeHTTP(writer, request)
+		writer.Body.Reset()
-	if got, want := writer.Code, http.StatusOK; got != want {
+		handler.ServeHTTP(writer, request)
-		t.Errorf("got HTTP status code %d, want %d", got, want)
-	}
 
-	want = "promhttp_metric_handler_requests_in_flight 1\n"
+		if got, want := mReg.gatherInvoked, i+2; got != want {
-	if got := writer.Body.String(); !strings.Contains(got, want) {
+			t.Fatalf("unexpected number of gather invokes, want %d, got %d", want, got)
-		t.Errorf("got body %q, does not contain %q", got, want)
+		}
-	}
+		if got, want := mReg.doneInvoked, i+2; got != want {
-	want = "promhttp_metric_handler_requests_total{code=\"200\"} 1\n"
+			t.Fatalf("unexpected number of done invokes, want %d, got %d", want, got)
-	if got := writer.Body.String(); !strings.Contains(got, want) {
+		}
-		t.Errorf("got body %q, does not contain %q", got, want)
+		if got, want := writer.Code, http.StatusOK; got != want {
+			t.Errorf("got HTTP status code %d, want %d", got, want)
+		}
+
+		want := "promhttp_metric_handler_requests_in_flight 1\n"
+		if got := writer.Body.String(); !strings.Contains(got, want) {
+			t.Errorf("got body %q, does not contain %q", got, want)
+		}
+		want = fmt.Sprintf("promhttp_metric_handler_requests_total{code=\"200\"} %d\n", i+1)
+		if got := writer.Body.String(); !strings.Contains(got, want) {
+			t.Errorf("got body %q, does not contain %q", got, want)
+		}
 	}
 }
 

prometheus/promhttp/instrument_client.go

@@ -19,7 +19,7 @@ import (
 	"net/http/httptrace"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 // The RoundTripperFunc type is an adapter to allow the use of ordinary
@@ -38,11 +38,11 @@ func (rt RoundTripperFunc) RoundTrip(r *http.Request) (*http.Response, error) {
 //
 // See the example for ExampleInstrumentRoundTripperDuration for example usage.
 func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripper) RoundTripperFunc {
-	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+	return func(r *http.Request) (*http.Response, error) {
 		gauge.Inc()
 		defer gauge.Dec()
 		return next.RoundTrip(r)
-	})
+	}
 }
 
 // InstrumentRoundTripperCounter is a middleware that wraps the provided
@@ -59,22 +59,28 @@ func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripp
 // If the wrapped RoundTripper panics or returns a non-nil error, the Counter
 // is not incremented.
 //
+// Use with WithExemplarFromContext to instrument the exemplars on the counter of requests.
+//
 // See the example for ExampleInstrumentRoundTripperDuration for example usage.
 func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.RoundTripper, opts ...Option) RoundTripperFunc {
-	rtOpts := &option{}
+	rtOpts := defaultOptions()
 	for _, o := range opts {
-		o(rtOpts)
+		o.apply(rtOpts)
 	}
 
 	code, method := checkLabels(counter)
 
-	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+	return func(r *http.Request) (*http.Response, error) {
 		resp, err := next.RoundTrip(r)
 		if err == nil {
-			counter.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)).Inc()
+			addWithExemplar(
+				counter.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)),
+				1,
+				rtOpts.getExemplarFn(r.Context()),
+			)
 		}
 		return resp, err
-	})
+	}
 }
 
 // InstrumentRoundTripperDuration is a middleware that wraps the provided
@@ -94,24 +100,30 @@ func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.Rou
 // If the wrapped RoundTripper panics or returns a non-nil error, no values are
 // reported.
 //
+// Use with WithExemplarFromContext to instrument the exemplars on the duration histograms.
+//
 // Note that this method is only guaranteed to never observe negative durations
 // if used with Go1.9+.
 func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundTripper, opts ...Option) RoundTripperFunc {
-	rtOpts := &option{}
+	rtOpts := defaultOptions()
 	for _, o := range opts {
-		o(rtOpts)
+		o.apply(rtOpts)
 	}
 
 	code, method := checkLabels(obs)
 
-	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+	return func(r *http.Request) (*http.Response, error) {
 		start := time.Now()
 		resp, err := next.RoundTrip(r)
 		if err == nil {
-			obs.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)).Observe(time.Since(start).Seconds())
+			observeWithExemplar(
+				obs.With(labels(code, method, r.Method, resp.StatusCode, rtOpts.extraMethods...)),
+				time.Since(start).Seconds(),
+				rtOpts.getExemplarFn(r.Context()),
+			)
 		}
 		return resp, err
-	})
+	}
 }
 
 // InstrumentTrace is used to offer flexibility in instrumenting the available
@@ -149,7 +161,7 @@ type InstrumentTrace struct {
 //
 // See the example for ExampleInstrumentRoundTripperDuration for example usage.
 func InstrumentRoundTripperTrace(it *InstrumentTrace, next http.RoundTripper) RoundTripperFunc {
-	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+	return func(r *http.Request) (*http.Response, error) {
 		start := time.Now()
 
 		trace := &httptrace.ClientTrace{
@@ -231,5 +243,5 @@ func InstrumentRoundTripperTrace(it *InstrumentTrace, next http.RoundTripper) Ro
 		r = r.WithContext(httptrace.WithClientTrace(r.Context(), trace))
 
 		return next.RoundTrip(r)
-	})
+	}
 }

prometheus/promhttp/instrument_client_test.go

@@ -18,14 +18,20 @@ import (
 	"log"
 	"net/http"
 	"net/http/httptest"
+	"reflect"
+	"sort"
 	"strings"
 	"testing"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus/testutil"
+
+	dto "github.com/prometheus/client_model/go"
+	"google.golang.org/protobuf/proto"
 )
 
-func makeInstrumentedClient() (*http.Client, *prometheus.Registry) {
+func makeInstrumentedClient(opts ...Option) (*http.Client, *prometheus.Registry) {
 	client := http.DefaultClient
 	client.Timeout = 1 * time.Second
 
@@ -91,13 +97,91 @@ func makeInstrumentedClient() (*http.Client, *prometheus.Registry) {
 	client.Transport = InstrumentRoundTripperInFlight(inFlightGauge,
 		InstrumentRoundTripperCounter(counter,
 			InstrumentRoundTripperTrace(trace,
-				InstrumentRoundTripperDuration(histVec, http.DefaultTransport),
+				InstrumentRoundTripperDuration(histVec, http.DefaultTransport, opts...),
 			),
-		),
+			opts...),
 	)
 	return client, reg
 }
 
+func labelsToLabelPair(l prometheus.Labels) []*dto.LabelPair {
+	ret := make([]*dto.LabelPair, 0, len(l))
+	for k, v := range l {
+		ret = append(ret, &dto.LabelPair{Name: proto.String(k), Value: proto.String(v)})
+	}
+	sort.Slice(ret, func(i, j int) bool {
+		return *ret[i].Name < *ret[j].Name
+	})
+	return ret
+}
+
+func assetMetricAndExemplars(
+	t *testing.T,
+	reg *prometheus.Registry,
+	expectedNumMetrics int,
+	expectedExemplar []*dto.LabelPair,
+) {
+	t.Helper()
+
+	mfs, err := reg.Gather()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if want, got := expectedNumMetrics, len(mfs); want != got {
+		t.Fatalf("unexpected number of metric families gathered, want %d, got %d", want, got)
+	}
+
+	for _, mf := range mfs {
+		if len(mf.Metric) == 0 {
+			t.Errorf("metric family %s must not be empty", mf.GetName())
+		}
+		for _, m := range mf.GetMetric() {
+			if c := m.GetCounter(); c != nil {
+				if len(expectedExemplar) == 0 {
+					if c.Exemplar != nil {
+						t.Errorf("expected no exemplar on the counter %v%v, got %v", mf.GetName(), m.Label, c.Exemplar.String())
+					}
+					continue
+				}
+
+				if c.Exemplar == nil {
+					t.Errorf("expected exemplar %v on the counter %v%v, got none", expectedExemplar, mf.GetName(), m.Label)
+					continue
+				}
+				if got := c.Exemplar.Label; !reflect.DeepEqual(expectedExemplar, got) {
+					t.Errorf("expected exemplar %v on the counter %v%v, got %v", expectedExemplar, mf.GetName(), m.Label, got)
+				}
+				continue
+			}
+			if h := m.GetHistogram(); h != nil {
+				found := false
+				for _, b := range h.GetBucket() {
+					if len(expectedExemplar) == 0 {
+						if b.Exemplar != nil {
+							t.Errorf("expected no exemplar on histogram %v%v bkt %v, got %v", mf.GetName(), m.Label, b.GetUpperBound(), b.Exemplar.String())
+						}
+						continue
+					}
+
+					if b.Exemplar == nil {
+						continue
+					}
+					if got := b.Exemplar.Label; !reflect.DeepEqual(expectedExemplar, got) {
+						t.Errorf("expected exemplar %v on the histogram %v%v on bkt %v, got %v", expectedExemplar, mf.GetName(), m.Label, b.GetUpperBound(), got)
+						continue
+					}
+					found = true
+					break
+				}
+
+				if len(expectedExemplar) > 0 && !found {
+					t.Errorf("expected exemplar %v on at least one bucket of the histogram %v%v, got none", expectedExemplar, mf.GetName(), m.Label)
+				}
+			}
+		}
+	}
+}
+
 func TestClientMiddlewareAPI(t *testing.T) {
 	client, reg := makeInstrumentedClient()
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -111,21 +195,28 @@ func TestClientMiddlewareAPI(t *testing.T) {
 	}
 	defer resp.Body.Close()
 
-	mfs, err := reg.Gather()
+	assetMetricAndExemplars(t, reg, 3, nil)
+}
+
+func TestClientMiddlewareAPI_WithExemplars(t *testing.T) {
+	exemplar := prometheus.Labels{"traceID": "example situation observed by this metric"}
+
+	client, reg := makeInstrumentedClient(WithExemplarFromContext(func(_ context.Context) prometheus.Labels { return exemplar }))
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer backend.Close()
+
+	resp, err := client.Get(backend.URL)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if want, got := 3, len(mfs); want != got {
+	defer resp.Body.Close()
-		t.Fatalf("unexpected number of metric families gathered, want %d, got %d", want, got)
+
-	}
+	assetMetricAndExemplars(t, reg, 3, labelsToLabelPair(exemplar))
-	for _, mf := range mfs {
-		if len(mf.Metric) == 0 {
-			t.Errorf("metric family %s must not be empty", mf.GetName())
-		}
-	}
 }
 
-func TestClientMiddlewareAPIWithRequestContext(t *testing.T) {
+func TestClientMiddlewareAPI_WithRequestContext(t *testing.T) {
 	client, reg := makeInstrumentedClient()
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusOK)
@@ -160,6 +251,19 @@ func TestClientMiddlewareAPIWithRequestContext(t *testing.T) {
 			t.Errorf("metric family %s must not be empty", mf.GetName())
 		}
 	}
+
+	// make sure counters aren't double-incremented (see #1117)
+	expected := `
+		# HELP client_api_requests_total A counter for requests from the wrapped client.
+		# TYPE client_api_requests_total counter
+		client_api_requests_total{code="200",method="get"} 1
+	`
+
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected),
+		"client_api_requests_total",
+	); err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestClientMiddlewareAPIWithRequestContextTimeout(t *testing.T) {

prometheus/promhttp/instrument_server.go

@@ -22,12 +22,32 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 // magicString is used for the hacky label test in checkLabels. Remove once fixed.
 const magicString = "zZgWfBxLqvG8kc8IMv3POi2Bb0tZI3vAnBx+gBaFi9FyPzB/CzKUer1yufDa"
 
+// observeWithExemplar is a wrapper for [prometheus.ExemplarAdder.ExemplarObserver],
+// which falls back to [prometheus.Observer.Observe] if no labels are provided.
+func observeWithExemplar(obs prometheus.Observer, val float64, labels map[string]string) {
+	if labels == nil {
+		obs.Observe(val)
+		return
+	}
+	obs.(prometheus.ExemplarObserver).ObserveWithExemplar(val, labels)
+}
+
+// addWithExemplar is a wrapper for [prometheus.ExemplarAdder.AddWithExemplar],
+// which falls back to [prometheus.Counter.Add] if no labels are provided.
+func addWithExemplar(obs prometheus.Counter, val float64, labels map[string]string) {
+	if labels == nil {
+		obs.Add(val)
+		return
+	}
+	obs.(prometheus.ExemplarAdder).AddWithExemplar(val, labels)
+}
+
 // InstrumentHandlerInFlight is a middleware that wraps the provided
 // http.Handler. It sets the provided prometheus.Gauge to the number of
 // requests currently handled by the wrapped http.Handler.
@@ -48,7 +68,7 @@ func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handl
 // names are "code" and "method". The function panics otherwise. For the "method"
 // label a predefined default label value set is used to filter given values.
 // Values besides predefined values will count as `unknown` method.
-//`WithExtraMethods` can be used to add more methods to the set. The Observe
+// `WithExtraMethods` can be used to add more methods to the set. The Observe
 // method of the Observer in the ObserverVec is called with the request duration
 // in seconds. Partitioning happens by HTTP status code and/or HTTP method if
 // the respective instance label names are present in the ObserverVec. For
@@ -62,28 +82,37 @@ func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handl
 // Note that this method is only guaranteed to never observe negative durations
 // if used with Go1.9+.
 func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
-	mwOpts := &option{}
+	hOpts := defaultOptions()
 	for _, o := range opts {
-		o(mwOpts)
+		o.apply(hOpts)
 	}
 
 	code, method := checkLabels(obs)
 
 	if code {
-		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		return func(w http.ResponseWriter, r *http.Request) {
 			now := time.Now()
 			d := newDelegator(w, nil)
 			next.ServeHTTP(d, r)
 
-			obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
+			observeWithExemplar(
-		})
+				obs.With(labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)),
+				time.Since(now).Seconds(),
+				hOpts.getExemplarFn(r.Context()),
+			)
+		}
 	}
 
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
 		now := time.Now()
 		next.ServeHTTP(w, r)
-		obs.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
+
-	})
+		observeWithExemplar(
+			obs.With(labels(code, method, r.Method, 0, hOpts.extraMethods...)),
+			time.Since(now).Seconds(),
+			hOpts.getExemplarFn(r.Context()),
+		)
+	}
 }
 
 // InstrumentHandlerCounter is a middleware that wraps the provided http.Handler
@@ -104,25 +133,34 @@ func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler, op
 //
 // See the example for InstrumentHandlerDuration for example usage.
 func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler, opts ...Option) http.HandlerFunc {
-	mwOpts := &option{}
+	hOpts := defaultOptions()
 	for _, o := range opts {
-		o(mwOpts)
+		o.apply(hOpts)
 	}
 
 	code, method := checkLabels(counter)
 
 	if code {
-		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		return func(w http.ResponseWriter, r *http.Request) {
 			d := newDelegator(w, nil)
 			next.ServeHTTP(d, r)
-			counter.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Inc()
+
-		})
+			addWithExemplar(
+				counter.With(labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)),
+				1,
+				hOpts.getExemplarFn(r.Context()),
+			)
+		}
 	}
 
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
 		next.ServeHTTP(w, r)
-		counter.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Inc()
+		addWithExemplar(
-	})
+			counter.With(labels(code, method, r.Method, 0, hOpts.extraMethods...)),
+			1,
+			hOpts.getExemplarFn(r.Context()),
+		)
+	}
 }
 
 // InstrumentHandlerTimeToWriteHeader is a middleware that wraps the provided
@@ -148,20 +186,24 @@ func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler,
 //
 // See the example for InstrumentHandlerDuration for example usage.
 func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
-	mwOpts := &option{}
+	hOpts := defaultOptions()
 	for _, o := range opts {
-		o(mwOpts)
+		o.apply(hOpts)
 	}
 
 	code, method := checkLabels(obs)
 
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
 		now := time.Now()
 		d := newDelegator(w, func(status int) {
-			obs.With(labels(code, method, r.Method, status, mwOpts.extraMethods...)).Observe(time.Since(now).Seconds())
+			observeWithExemplar(
+				obs.With(labels(code, method, r.Method, status, hOpts.extraMethods...)),
+				time.Since(now).Seconds(),
+				hOpts.getExemplarFn(r.Context()),
+			)
 		})
 		next.ServeHTTP(d, r)
-	})
+	}
 }
 
 // InstrumentHandlerRequestSize is a middleware that wraps the provided
@@ -184,27 +226,34 @@ func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Ha
 //
 // See the example for InstrumentHandlerDuration for example usage.
 func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.HandlerFunc {
-	mwOpts := &option{}
+	hOpts := defaultOptions()
 	for _, o := range opts {
-		o(mwOpts)
+		o.apply(hOpts)
 	}
 
 	code, method := checkLabels(obs)
-
 	if code {
-		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		return func(w http.ResponseWriter, r *http.Request) {
 			d := newDelegator(w, nil)
 			next.ServeHTTP(d, r)
 			size := computeApproximateRequestSize(r)
-			obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(float64(size))
+			observeWithExemplar(
-		})
+				obs.With(labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)),
+				float64(size),
+				hOpts.getExemplarFn(r.Context()),
+			)
+		}
 	}
 
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
 		next.ServeHTTP(w, r)
 		size := computeApproximateRequestSize(r)
-		obs.With(labels(code, method, r.Method, 0, mwOpts.extraMethods...)).Observe(float64(size))
+		observeWithExemplar(
-	})
+			obs.With(labels(code, method, r.Method, 0, hOpts.extraMethods...)),
+			float64(size),
+			hOpts.getExemplarFn(r.Context()),
+		)
+	}
 }
 
 // InstrumentHandlerResponseSize is a middleware that wraps the provided
@@ -227,9 +276,9 @@ func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler,
 //
 // See the example for InstrumentHandlerDuration for example usage.
 func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler, opts ...Option) http.Handler {
-	mwOpts := &option{}
+	hOpts := defaultOptions()
 	for _, o := range opts {
-		o(mwOpts)
+		o.apply(hOpts)
 	}
 
 	code, method := checkLabels(obs)
@@ -237,7 +286,11 @@ func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		d := newDelegator(w, nil)
 		next.ServeHTTP(d, r)
-		obs.With(labels(code, method, r.Method, d.Status(), mwOpts.extraMethods...)).Observe(float64(d.Written()))
+		observeWithExemplar(
+			obs.With(labels(code, method, r.Method, d.Status(), hOpts.extraMethods...)),
+			float64(d.Written()),
+			hOpts.getExemplarFn(r.Context()),
+		)
 	})
 }
 
@@ -246,7 +299,7 @@ func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler
 // Collector does not have a Desc or has more than one Desc or its Desc is
 // invalid. It also panics if the Collector has any non-const, non-curried
 // labels that are not named "code" or "method".
-func checkLabels(c prometheus.Collector) (code bool, method bool) {
+func checkLabels(c prometheus.Collector) (code, method bool) {
 	// TODO(beorn7): Remove this hacky way to check for instance labels
 	// once Descriptors can have their dimensionality queried.
 	var (

prometheus/promhttp/instrument_server_test.go

@@ -14,13 +14,14 @@
 package promhttp
 
 import (
+	"context"
 	"io"
 	"log"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 func TestLabelCheck(t *testing.T) {
@@ -145,7 +146,6 @@ func TestLabelCheck(t *testing.T) {
 				},
 				append(sc.varLabels, sc.curriedLabels...),
 			))
-			//nolint:typecheck // Ignore declared but unused error.
 			for _, l := range sc.curriedLabels {
 				c = c.MustCurryWith(prometheus.Labels{l: "dummy"})
 				o = o.MustCurryWith(prometheus.Labels{l: "dummy"})
@@ -279,7 +279,7 @@ func TestLabels(t *testing.T) {
 			ok:         false,
 		},
 	}
-	checkLabels := func(labels []string) (gotCode bool, gotMethod bool) {
+	checkLabels := func(labels []string) (gotCode, gotMethod bool) {
 		for _, label := range labels {
 			switch label {
 			case "code":
@@ -321,7 +321,7 @@ func TestLabels(t *testing.T) {
 	}
 }
 
-func TestMiddlewareAPI(t *testing.T) {
+func makeInstrumentedHandler(handler http.HandlerFunc, opts ...Option) (http.Handler, *prometheus.Registry) {
 	reg := prometheus.NewRegistry()
 
 	inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
@@ -366,25 +366,43 @@ func TestMiddlewareAPI(t *testing.T) {
 		[]string{},
 	)
 
-	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Write([]byte("OK"))
-	})
-
 	reg.MustRegister(inFlightGauge, counter, histVec, responseSize, writeHeaderVec)
 
-	chain := InstrumentHandlerInFlight(inFlightGauge,
+	return InstrumentHandlerInFlight(inFlightGauge,
 		InstrumentHandlerCounter(counter,
 			InstrumentHandlerDuration(histVec,
 				InstrumentHandlerTimeToWriteHeader(writeHeaderVec,
-					InstrumentHandlerResponseSize(responseSize, handler),
+					InstrumentHandlerResponseSize(responseSize, handler, opts...),
-				),
+					opts...),
-			),
+				opts...),
-		),
+			opts...),
-	)
+	), reg
+}
+
+func TestMiddlewareAPI(t *testing.T) {
+	chain, reg := makeInstrumentedHandler(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("OK"))
+	})
 
 	r, _ := http.NewRequest("GET", "www.example.com", nil)
 	w := httptest.NewRecorder()
 	chain.ServeHTTP(w, r)
+
+	assetMetricAndExemplars(t, reg, 5, nil)
+}
+
+func TestMiddlewareAPI_WithExemplars(t *testing.T) {
+	exemplar := prometheus.Labels{"traceID": "example situation observed by this metric"}
+
+	chain, reg := makeInstrumentedHandler(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte("OK"))
+	}, WithExemplarFromContext(func(_ context.Context) prometheus.Labels { return exemplar }))
+
+	r, _ := http.NewRequest("GET", "www.example.com", nil)
+	w := httptest.NewRecorder()
+	chain.ServeHTTP(w, r)
+
+	assetMetricAndExemplars(t, reg, 5, labelsToLabelPair(exemplar))
 }
 
 func TestInstrumentTimeToFirstWrite(t *testing.T) {

prometheus/promhttp/option.go

@@ -13,19 +13,46 @@
 
 package promhttp
 
-// Option are used to configure a middleware or round tripper..
+import (
-type Option func(*option)
+	"context"
 
-type option struct {
+	"git.internal/re/client_golang/prometheus"
-	extraMethods []string
+)
+
+// Option are used to configure both handler (middleware) or round tripper.
+type Option interface {
+	apply(*options)
 }
 
+// options store options for both a handler or round tripper.
+type options struct {
+	extraMethods  []string
+	getExemplarFn func(requestCtx context.Context) prometheus.Labels
+}
+
+func defaultOptions() *options {
+	return &options{getExemplarFn: func(ctx context.Context) prometheus.Labels { return nil }}
+}
+
+type optionApplyFunc func(*options)
+
+func (o optionApplyFunc) apply(opt *options) { o(opt) }
+
 // WithExtraMethods adds additional HTTP methods to the list of allowed methods.
 // See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods for the default list.
 //
 // See the example for ExampleInstrumentHandlerWithExtraMethods for example usage.
 func WithExtraMethods(methods ...string) Option {
-	return func(o *option) {
+	return optionApplyFunc(func(o *options) {
 		o.extraMethods = methods
-	}
+	})
+}
+
+// WithExemplarFromContext adds allows to put a hook to all counter and histogram metrics.
+// If the hook function returns non-nil labels, exemplars will be added for that request, otherwise metric
+// will get instrumented without exemplar.
+func WithExemplarFromContext(getExemplarFn func(requestCtx context.Context) prometheus.Labels) Option {
+	return optionApplyFunc(func(o *options) {
+		o.getExemplarFn = getExemplarFn
+	})
 }

prometheus/promhttp/option_test.go

@@ -17,7 +17,7 @@ import (
 	"log"
 	"net/http"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 func ExampleInstrumentHandlerWithExtraMethods() {
@@ -50,11 +50,10 @@ func ExampleInstrumentHandlerWithExtraMethods() {
 
 	// Instrument the handlers with all the metrics, injecting the "handler"
 	// label by currying.
-	pullChain :=
+	pullChain := InstrumentHandlerDuration(duration.MustCurryWith(prometheus.Labels{"handler": "pull"}),
-		InstrumentHandlerDuration(duration.MustCurryWith(prometheus.Labels{"handler": "pull"}),
+		InstrumentHandlerCounter(counter, pullHandler, opts),
-			InstrumentHandlerCounter(counter, pullHandler, opts),
+		opts,
-			opts,
+	)
-		)
 
 	http.Handle("/metrics", Handler())
 	http.Handle("/pull", pullChain)

prometheus/push/example_add_from_gatherer_test.go

@@ -17,8 +17,8 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/push"
+	"git.internal/re/client_golang/prometheus/push"
 )
 
 var (

prometheus/push/examples_test.go

@@ -16,8 +16,8 @@ package push_test
 import (
 	"fmt"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/push"
+	"git.internal/re/client_golang/prometheus/push"
 )
 
 func ExamplePusher_Push() {

prometheus/push/push.go

@@ -15,17 +15,17 @@
 // builder approach. Create a Pusher with New and then add the various options
 // by using its methods, finally calling Add or Push, like this:
 //
-//    // Easy case:
+//	// Easy case:
-//    push.New("http://example.org/metrics", "my_job").Gatherer(myRegistry).Push()
+//	push.New("http://example.org/metrics", "my_job").Gatherer(myRegistry).Push()
 //
-//    // Complex case:
+//	// Complex case:
-//    push.New("http://example.org/metrics", "my_job").
+//	push.New("http://example.org/metrics", "my_job").
-//        Collector(myCollector1).
+//	    Collector(myCollector1).
-//        Collector(myCollector2).
+//	    Collector(myCollector2).
-//        Grouping("zone", "xy").
+//	    Grouping("zone", "xy").
-//        Client(&myHTTPClient).
+//	    Client(&myHTTPClient).
-//        BasicAuth("top", "secret").
+//	    BasicAuth("top", "secret").
-//        Add()
+//	    Add()
 //
 // See the examples section for more detailed examples.
 //
@@ -36,10 +36,11 @@ package push
 
 import (
 	"bytes"
+	"context"
 	"encoding/base64"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/url"
 	"strings"
@@ -47,7 +48,7 @@ import (
 	"github.com/prometheus/common/expfmt"
 	"github.com/prometheus/common/model"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 const (
@@ -97,9 +98,7 @@ func New(url, job string) *Pusher {
 	if !strings.Contains(url, "://") {
 		url = "http://" + url
 	}
-	if strings.HasSuffix(url, "/") {
+	url = strings.TrimSuffix(url, "/")
-		url = url[:len(url)-1]
-	}
 
 	return &Pusher{
 		error:      err,
@@ -123,14 +122,28 @@ func New(url, job string) *Pusher {
 // Push returns the first error encountered by any method call (including this
 // one) in the lifetime of the Pusher.
 func (p *Pusher) Push() error {
-	return p.push(http.MethodPut)
+	return p.push(context.Background(), http.MethodPut)
+}
+
+// PushContext is like Push but includes a context.
+//
+// If the context expires before HTTP request is complete, an error is returned.
+func (p *Pusher) PushContext(ctx context.Context) error {
+	return p.push(ctx, http.MethodPut)
 }
 
 // Add works like push, but only previously pushed metrics with the same name
 // (and the same job and other grouping labels) will be replaced. (It uses HTTP
 // method “POST” to push to the Pushgateway.)
 func (p *Pusher) Add() error {
-	return p.push(http.MethodPost)
+	return p.push(context.Background(), http.MethodPost)
+}
+
+// AddContext is like Add but includes a context.
+//
+// If the context expires before HTTP request is complete, an error is returned.
+func (p *Pusher) AddContext(ctx context.Context) error {
+	return p.push(ctx, http.MethodPost)
 }
 
 // Gatherer adds a Gatherer to the Pusher, from which metrics will be gathered
@@ -155,6 +168,11 @@ func (p *Pusher) Collector(c prometheus.Collector) *Pusher {
 	return p
 }
 
+// Error returns the error that was encountered.
+func (p *Pusher) Error() error {
+	return p.error
+}
+
 // Grouping adds a label pair to the grouping key of the Pusher, replacing any
 // previously added label pair with the same label name. Note that setting any
 // labels in the grouping key that are already contained in the metrics to push
@@ -227,13 +245,13 @@ func (p *Pusher) Delete() error {
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusAccepted {
-		body, _ := ioutil.ReadAll(resp.Body) // Ignore any further error as this is for an error message only.
+		body, _ := io.ReadAll(resp.Body) // Ignore any further error as this is for an error message only.
 		return fmt.Errorf("unexpected status code %d while deleting %s: %s", resp.StatusCode, p.fullURL(), body)
 	}
 	return nil
 }
 
-func (p *Pusher) push(method string) error {
+func (p *Pusher) push(ctx context.Context, method string) error {
 	if p.error != nil {
 		return p.error
 	}
@@ -258,9 +276,13 @@ func (p *Pusher) push(method string) error {
 				}
 			}
 		}
-		enc.Encode(mf)
+		if err := enc.Encode(mf); err != nil {
+			return fmt.Errorf(
+				"failed to encode metric familty %s, error is %w",
+				mf.GetName(), err)
+		}
 	}
-	req, err := http.NewRequest(method, p.fullURL(), buf)
+	req, err := http.NewRequestWithContext(ctx, method, p.fullURL(), buf)
 	if err != nil {
 		return err
 	}
@@ -275,7 +297,7 @@ func (p *Pusher) push(method string) error {
 	defer resp.Body.Close()
 	// Depending on version and configuration of the PGW, StatusOK or StatusAccepted may be returned.
 	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusAccepted {
-		body, _ := ioutil.ReadAll(resp.Body) // Ignore any further error as this is for an error message only.
+		body, _ := io.ReadAll(resp.Body) // Ignore any further error as this is for an error message only.
 		return fmt.Errorf("unexpected status code %d while pushing to %s: %s", resp.StatusCode, p.fullURL(), body)
 	}
 	return nil

prometheus/push/push_test.go

@@ -15,18 +15,18 @@ package push
 
 import (
 	"bytes"
-	"io/ioutil"
+	"errors"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
 	"github.com/prometheus/common/expfmt"
 
-	"github.com/prometheus/client_golang/prometheus"
+	"git.internal/re/client_golang/prometheus"
 )
 
 func TestPush(t *testing.T) {
-
 	var (
 		lastMethod string
 		lastBody   []byte
@@ -39,7 +39,7 @@ func TestPush(t *testing.T) {
 		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			lastMethod = r.Method
 			var err error
-			lastBody, err = ioutil.ReadAll(r.Body)
+			lastBody, err = io.ReadAll(r.Body)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -201,8 +201,8 @@ func TestPush(t *testing.T) {
 		Push(); err == nil {
 		t.Error("push with empty job succeeded")
 	} else {
-		if got, want := err, errJobEmpty; got != want {
+		if want := errJobEmpty; !errors.Is(err, want) {
-			t.Errorf("got error %q, want %q", got, want)
+			t.Errorf("got error %q, want %q", err, want)
 		}
 	}
 

prometheus/registry.go

@@ -15,8 +15,8 @@ package prometheus
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -32,7 +32,7 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/client_golang/prometheus/internal"
+	"git.internal/re/client_golang/prometheus/internal"
 )
 
 const (
@@ -252,9 +252,12 @@ func (errs MultiError) MaybeUnwrap() error {
 }
 
 // Registry registers Prometheus collectors, collects their metrics, and gathers
-// them into MetricFamilies for exposition. It implements both Registerer and
+// them into MetricFamilies for exposition. It implements Registerer, Gatherer,
-// Gatherer. The zero value is not usable. Create instances with NewRegistry or
+// and Collector. The zero value is not usable. Create instances with
-// NewPedanticRegistry.
+// NewRegistry or NewPedanticRegistry.
+//
+// Registry implements Collector to allow it to be used for creating groups of
+// metrics. See the Grouping example for how this can be done.
 type Registry struct {
 	mtx                   sync.RWMutex
 	collectorsByID        map[uint64]Collector // ID is a hash of the descIDs.
@@ -289,7 +292,7 @@ func (r *Registry) Register(c Collector) error {
 
 		// Is the descriptor valid at all?
 		if desc.err != nil {
-			return fmt.Errorf("descriptor %s is invalid: %s", desc, desc.err)
+			return fmt.Errorf("descriptor %s is invalid: %w", desc, desc.err)
 		}
 
 		// Is the descID unique?
@@ -407,6 +410,14 @@ func (r *Registry) MustRegister(cs ...Collector) {
 
 // Gather implements Gatherer.
 func (r *Registry) Gather() ([]*dto.MetricFamily, error) {
+	r.mtx.RLock()
+
+	if len(r.collectorsByID) == 0 && len(r.uncheckedCollectors) == 0 {
+		// Fast path.
+		r.mtx.RUnlock()
+		return nil, nil
+	}
+
 	var (
 		checkedMetricChan   = make(chan Metric, capMetricChan)
 		uncheckedMetricChan = make(chan Metric, capMetricChan)
@@ -416,7 +427,6 @@ func (r *Registry) Gather() ([]*dto.MetricFamily, error) {
 		registeredDescIDs   map[uint64]struct{} // Only used for pedantic checks
 	)
 
-	r.mtx.RLock()
 	goroutineBudget := len(r.collectorsByID) + len(r.uncheckedCollectors)
 	metricFamiliesByName := make(map[string]*dto.MetricFamily, len(r.dimHashesByName))
 	checkedCollectors := make(chan Collector, len(r.collectorsByID))
@@ -549,6 +559,31 @@ func (r *Registry) Gather() ([]*dto.MetricFamily, error) {
 	return internal.NormalizeMetricFamilies(metricFamiliesByName), errs.MaybeUnwrap()
 }
 
+// Describe implements Collector.
+func (r *Registry) Describe(ch chan<- *Desc) {
+	r.mtx.RLock()
+	defer r.mtx.RUnlock()
+
+	// Only report the checked Collectors; unchecked collectors don't report any
+	// Desc.
+	for _, c := range r.collectorsByID {
+		c.Describe(ch)
+	}
+}
+
+// Collect implements Collector.
+func (r *Registry) Collect(ch chan<- Metric) {
+	r.mtx.RLock()
+	defer r.mtx.RUnlock()
+
+	for _, c := range r.collectorsByID {
+		c.Collect(ch)
+	}
+	for _, c := range r.uncheckedCollectors {
+		c.Collect(ch)
+	}
+}
+
 // WriteToTextfile calls Gather on the provided Gatherer, encodes the result in the
 // Prometheus text format, and writes it to a temporary file. Upon success, the
 // temporary file is renamed to the provided filename.
@@ -556,7 +591,7 @@ func (r *Registry) Gather() ([]*dto.MetricFamily, error) {
 // This is intended for use with the textfile collector of the node exporter.
 // Note that the node exporter expects the filename to be suffixed with ".prom".
 func WriteToTextfile(filename string, g Gatherer) error {
-	tmp, err := ioutil.TempFile(filepath.Dir(filename), filepath.Base(filename))
+	tmp, err := os.CreateTemp(filepath.Dir(filename), filepath.Base(filename))
 	if err != nil {
 		return err
 	}
@@ -575,7 +610,7 @@ func WriteToTextfile(filename string, g Gatherer) error {
 		return err
 	}
 
-	if err := os.Chmod(tmp.Name(), 0644); err != nil {
+	if err := os.Chmod(tmp.Name(), 0o644); err != nil {
 		return err
 	}
 	return os.Rename(tmp.Name(), filename)
@@ -596,7 +631,7 @@ func processMetric(
 	}
 	dtoMetric := &dto.Metric{}
 	if err := metric.Write(dtoMetric); err != nil {
-		return fmt.Errorf("error collecting metric %v: %s", desc, err)
+		return fmt.Errorf("error collecting metric %v: %w", desc, err)
 	}
 	metricFamily, ok := metricFamiliesByName[desc.fqName]
 	if ok { // Existing name.
@@ -718,12 +753,13 @@ func (gs Gatherers) Gather() ([]*dto.MetricFamily, error) {
 	for i, g := range gs {
 		mfs, err := g.Gather()
 		if err != nil {
-			if multiErr, ok := err.(MultiError); ok {
+			multiErr := MultiError{}
+			if errors.As(err, &multiErr) {
 				for _, err := range multiErr {
-					errs = append(errs, fmt.Errorf("[from Gatherer #%d] %s", i+1, err))
+					errs = append(errs, fmt.Errorf("[from Gatherer #%d] %w", i+1, err))
 				}
 			} else {
-				errs = append(errs, fmt.Errorf("[from Gatherer #%d] %s", i+1, err))
+				errs = append(errs, fmt.Errorf("[from Gatherer #%d] %w", i+1, err))
 			}
 		}
 		for _, mf := range mfs {
@@ -884,11 +920,11 @@ func checkMetricConsistency(
 	h.Write(separatorByteSlice)
 	// Make sure label pairs are sorted. We depend on it for the consistency
 	// check.
-	if !sort.IsSorted(labelPairSorter(dtoMetric.Label)) {
+	if !sort.IsSorted(internal.LabelPairSorter(dtoMetric.Label)) {
 		// We cannot sort dtoMetric.Label in place as it is immutable by contract.
 		copiedLabels := make([]*dto.LabelPair, len(dtoMetric.Label))
 		copy(copiedLabels, dtoMetric.Label)
-		sort.Sort(labelPairSorter(copiedLabels))
+		sort.Sort(internal.LabelPairSorter(copiedLabels))
 		dtoMetric.Label = copiedLabels
 	}
 	for _, lp := range dtoMetric.Label {
@@ -935,7 +971,7 @@ func checkDescConsistency(
 			metricFamily.GetName(), dtoMetric, desc,
 		)
 	}
-	sort.Sort(labelPairSorter(lpsFromDesc))
+	sort.Sort(internal.LabelPairSorter(lpsFromDesc))
 	for i, lpFromDesc := range lpsFromDesc {
 		lpFromMetric := dtoMetric.Label[i]
 		if lpFromDesc.GetName() != lpFromMetric.GetName() ||
@@ -948,3 +984,89 @@ func checkDescConsistency(
 	}
 	return nil
 }
+
+var _ TransactionalGatherer = &MultiTRegistry{}
+
+// MultiTRegistry is a TransactionalGatherer that joins gathered metrics from multiple
+// transactional gatherers.
+//
+// It is caller responsibility to ensure two registries have mutually exclusive metric families,
+// no deduplication will happen.
+type MultiTRegistry struct {
+	tGatherers []TransactionalGatherer
+}
+
+// NewMultiTRegistry creates MultiTRegistry.
+func NewMultiTRegistry(tGatherers ...TransactionalGatherer) *MultiTRegistry {
+	return &MultiTRegistry{
+		tGatherers: tGatherers,
+	}
+}
+
+// Gather implements TransactionalGatherer interface.
+func (r *MultiTRegistry) Gather() (mfs []*dto.MetricFamily, done func(), err error) {
+	errs := MultiError{}
+
+	dFns := make([]func(), 0, len(r.tGatherers))
+	// TODO(bwplotka): Implement concurrency for those?
+	for _, g := range r.tGatherers {
+		// TODO(bwplotka): Check for duplicates?
+		m, d, err := g.Gather()
+		errs.Append(err)
+
+		mfs = append(mfs, m...)
+		dFns = append(dFns, d)
+	}
+
+	// TODO(bwplotka): Consider sort in place, given metric family in gather is sorted already.
+	sort.Slice(mfs, func(i, j int) bool {
+		return *mfs[i].Name < *mfs[j].Name
+	})
+	return mfs, func() {
+		for _, d := range dFns {
+			d()
+		}
+	}, errs.MaybeUnwrap()
+}
+
+// TransactionalGatherer represents transactional gatherer that can be triggered to notify gatherer that memory
+// used by metric family is no longer used by a caller. This allows implementations with cache.
+type TransactionalGatherer interface {
+	// Gather returns metrics in a lexicographically sorted slice
+	// of uniquely named MetricFamily protobufs. Gather ensures that the
+	// returned slice is valid and self-consistent so that it can be used
+	// for valid exposition. As an exception to the strict consistency
+	// requirements described for metric.Desc, Gather will tolerate
+	// different sets of label names for metrics of the same metric family.
+	//
+	// Even if an error occurs, Gather attempts to gather as many metrics as
+	// possible. Hence, if a non-nil error is returned, the returned
+	// MetricFamily slice could be nil (in case of a fatal error that
+	// prevented any meaningful metric collection) or contain a number of
+	// MetricFamily protobufs, some of which might be incomplete, and some
+	// might be missing altogether. The returned error (which might be a
+	// MultiError) explains the details. Note that this is mostly useful for
+	// debugging purposes. If the gathered protobufs are to be used for
+	// exposition in actual monitoring, it is almost always better to not
+	// expose an incomplete result and instead disregard the returned
+	// MetricFamily protobufs in case the returned error is non-nil.
+	//
+	// Important: done is expected to be triggered (even if the error occurs!)
+	// once caller does not need returned slice of dto.MetricFamily.
+	Gather() (_ []*dto.MetricFamily, done func(), err error)
+}
+
+// ToTransactionalGatherer transforms Gatherer to transactional one with noop as done function.
+func ToTransactionalGatherer(g Gatherer) TransactionalGatherer {
+	return &noTransactionGatherer{g: g}
+}
+
+type noTransactionGatherer struct {
+	g Gatherer
+}
+
+// Gather implements TransactionalGatherer interface.
+func (g *noTransactionGatherer) Gather() (_ []*dto.MetricFamily, done func(), err error) {
+	mfs, err := g.g.Gather()
+	return mfs, func() {}, err
+}