Merge pull request #40 from prometheus/drain-collect-channel

Drain collector channel when returning prematurely.

.travis.yml

@@ -1,7 +1,7 @@
 language: go
 
 go:
- - 1.2.1
+ - 1.4
 
 script:
  - make -f Makefile

Makefile

@@ -18,7 +18,7 @@ MAC_OS_X_VERSION ?= 10.8
 
 BUILD_PATH = $(PWD)/.build
 
-export GO_VERSION = 1.2.1
+export GO_VERSION = 1.4
 export GOOS 	    = $(subst Darwin,darwin,$(subst Linux,linux,$(OS)))
 
 ifeq ($(GOOS),darwin)
@@ -29,6 +29,7 @@ endif
 
 export GOARCH		  = $(subst x86_64,amd64,$(ARCH))
 export GOPKG		  = go$(GO_VERSION).$(GOOS)-$(GOARCH)$(RELEASE_SUFFIX).tar.gz
+export GOURL		  = http://golang.org/dl
 export GOROOT		  = $(BUILD_PATH)/root/go
 export GOPATH		  = $(BUILD_PATH)/root/gopath
 export GOCC		  = $(GOROOT)/bin/go
@@ -57,7 +58,7 @@ $(BUILD_PATH)/root: $(BUILD_PATH)
 	mkdir -vp $(BUILD_PATH)/root
 
 $(BUILD_PATH)/cache/$(GOPKG): $(BUILD_PATH)/cache
-	curl -o $@ http://go.googlecode.com/files/$(GOPKG)
+	curl -o $@ -L $(GOURL)/$(GOPKG)
 
 $(GOCC): $(BUILD_PATH)/root $(BUILD_PATH)/cache/$(GOPKG)
 	tar -C $(BUILD_PATH)/root -xzf $(BUILD_PATH)/cache/$(GOPKG)

prometheus/registry.go

@@ -33,8 +33,8 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"compress/gzip"
 	"code.google.com/p/goprotobuf/proto"
+	"compress/gzip"
 
 	"github.com/prometheus/client_golang/_vendor/goautoneg"
 	"github.com/prometheus/client_golang/model"
@@ -424,6 +424,12 @@ func (r *registry) writePB(w io.Writer, writeEncoded encoder) (int, error) {
 	}
 	r.mtx.RUnlock()
 
+	// Drain metricChan in case of premature return.
+	defer func() {
+		for range metricChan {
+		}
+	}()
+
 	// Gather.
 	for metric := range metricChan {
 		// This could be done concurrently, too, but it required locking