Commit Graph

32 Commits

Author SHA1 Message Date
Arthur Silva Sens df7fa49417
Extend Counters, Summaries and Histograms with creation timestamp (#1313)
* Extend Counters, Summaries and Histograms with creation timestamp

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

* Backport created timestamp to existing tests

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

* Last touches (readability and consistency)

Changes:

* Comments for "now" are more explicit and not inlined.
* populateMetrics is simpler and bit more efficient without timestamp to time to timestamp conversionts for more common code.
* Test consistency and simplicity - the fewer variables the better.
* Fixed inconsistency for v2 and MetricVec - let's pass opt.now consistently.
* We don't need TestCounterXXXTimestamp - we test CT in many other places already.
* Added more involved test for counter vectors with created timestamp.
* Refactored normalization for simplicity.
* Make histogram, summaries now consistent.
* Simplified histograms CT flow and implemented proper CT on reset.

TODO for next PRs:
* NewConstSummary and NewConstHistogram - ability to specify CTs there.

Signed-off-by: bwplotka <bwplotka@gmail.com>

* Update prometheus/counter_test.go

Co-authored-by: Arthur Silva Sens <arthursens2005@gmail.com>
Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

---------

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>
Signed-off-by: bwplotka <bwplotka@gmail.com>
Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>
Co-authored-by: bwplotka <bwplotka@gmail.com>
2023-09-21 10:46:54 +01:00
zhsj 7f99379117
Replace deprecated github.com/golang/protobuf package (#1183)
This replaces usage of proto.{Float64,Int32,Int64,String,Uint32,Uint64},
which doesn't break the interface.

And remove usage of proto.MarshalTextString in wrap_test.go

Updates: #1175

Signed-off-by: Shengjing Zhu <zhsj@debian.org>

Signed-off-by: Shengjing Zhu <zhsj@debian.org>
2022-12-22 16:14:00 +01:00
Balint Zsilavecz dcea97eee2
Fix `CumulativeCount` value of `+Inf` bucket created from exemplar (#1148)
* Fix `CumulativeCount` value of `+Inf` bucket created from exemplar

Signed-off-by: Balint Zsilavecz <balint.zsilavecz@skyscanner.net>

* Update prometheus/metric_test.go

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Signed-off-by: Balint Zsilavecz <balint.zsilavecz@skyscanner.net>

* Clarify description of implicit `+Inf` bucket count

Signed-off-by: Balint Zsilavecz <balint.zsilavecz@skyscanner.net>

* Fix test variables

Signed-off-by: Balint Zsilavecz <balint.zsilavecz@skyscanner.net>

Signed-off-by: Balint Zsilavecz <balint.zsilavecz@skyscanner.net>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
2022-10-13 13:52:19 +02:00
Bartlomiej Plotka 3faf3bae70
Fixed support for unordered input of exemplars. (#1100)
Signed-off-by: bwplotka <bwplotka@gmail.com>
2022-08-02 11:32:30 +02:00
Arun Mahendra 807b1ee73c
explicitly add +inf bucket in withExemplarsMetric (#1094)
* explicitly adding +inf bucket to withExemplarsMetric

Signed-off-by: Arun Mahendra <arun.mahendra@shopify.com>

* Update prometheus/metric_test.go

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Update prometheus/metric.go

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>

* updated comment and removed unnecessary test

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
2022-08-02 10:48:18 +02:00
William Perron 66837e3298
Add exemplar support for const histogram and const metric (#986)
* Add support for exemplars on constHistogram

Co-authored-by: William Perron <william.perron@shopify.com>
Signed-off-by: William Perron <william.perron@shopify.com>

* remove GetExemplars function

Signed-off-by: William Perron <william.perron@shopify.com>

* fixed linting warnings

reduce repetition in constHistogram w/ exemplar

Signed-off-by: William Perron <william.perron@shopify.com>

* Add values to correct bucket

Signed-off-by: William Perron <william.perron@shopify.com>

* Misc fixes

Co-authored-by: Francis Bogsanyi <francis.bogsanyi@shopify.com>

Signed-off-by: William Perron <william.perron@shopify.com>

* avoid panic when there are fewer buckets than exemplars

Co-authored-by: Arun Mahendra <arun.mahendra@shopify.com>

Signed-off-by: William Perron <william.perron@shopify.com>

* Added MustNewMetricWithExemplars that wraps metrics with exemplar (#3)

Changes:
* Make sure to not "leak" dto.Metric
* Reused upper bounds we already have for histogram
* Common code for all types.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Co-authored-by: Arun Mahendra <arun.mahendra@shopify.com>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
2022-03-17 11:30:41 +00:00
Bartlomiej Plotka 1f81b3e913
Added Transactional Gatherer allowed cached solutions (#989)
* Added cached collector.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

update.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Attempt 2

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Added blocking registry, with raw collector and transactional handler.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Added fast path to normal (empty) registry to save 8 allocs and 3K5B per Gather.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Simplified API, added tests.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Fix.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Simplified implementation.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Added benchmark.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

Optimized.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Optimization attempt.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Revert "Optimization attempt."

This reverts commit 2fcaf51be9.

Optimization was not worth it:

 benchstat v1.txt v2.txt
name                                                           old time/op    new time/op    delta
CachedTGatherer_Update/Update_of_one_element_without_reset-12    2.64µs ± 0%    4.05µs ± 0%   ~     (p=1.000 n=1+1)
CachedTGatherer_Update/Update_of_all_elements_with_reset-12       701ms ± 0%     358ms ± 0%   ~     (p=1.000 n=1+1)
CachedTGatherer_Update/Gather-12                                  535µs ± 0%  703934µs ± 0%   ~     (p=1.000 n=1+1)

name                                                           old alloc/op   new alloc/op   delta
CachedTGatherer_Update/Update_of_one_element_without_reset-12      208B ± 0%      208B ± 0%   ~     (all equal)
CachedTGatherer_Update/Update_of_all_elements_with_reset-12      40.2MB ± 0%    41.1MB ± 0%   ~     (p=1.000 n=1+1)
CachedTGatherer_Update/Gather-12                                 48.6kB ± 0%    84.3kB ± 0%   ~     (p=1.000 n=1+1)

name                                                           old allocs/op  new allocs/op  delta
CachedTGatherer_Update/Update_of_one_element_without_reset-12      3.00 ± 0%      3.00 ± 0%   ~     (all equal)
CachedTGatherer_Update/Update_of_all_elements_with_reset-12        6.00 ± 0%   4003.00 ± 0%   ~     (p=1.000 n=1+1)
CachedTGatherer_Update/Gather-12                                  1.00k ± 0%     2.01k ± 0%   ~     (p=1.000 n=1+1)

* nit.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Another optimization attempt.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* rename and further optimization.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Hopefully final optimization.

benchstat -delta-test=none v6.txt v9.txt
name                                                           old time/op    new time/op    delta
CachedTGatherer_Update/Update_of_one_element_without_reset-12    13.1ms ± 0%     0.0ms ± 0%  -99.81%
CachedTGatherer_Update/Update_of_all_elements_with_reset-12       309ms ± 0%     282ms ± 0%   -8.77%
CachedTGatherer_Update/Gather-12                                  422ms ± 0%       0ms ± 0%  -99.95%

name                                                           old alloc/op   new alloc/op   delta
CachedTGatherer_Update/Update_of_one_element_without_reset-12      208B ± 0%      208B ± 0%    0.00%
CachedTGatherer_Update/Update_of_all_elements_with_reset-12      2.47kB ± 0%    1.67kB ± 0%  -32.56%
CachedTGatherer_Update/Gather-12                                 52.8kB ± 0%    24.6kB ± 0%  -53.34%

name                                                           old allocs/op  new allocs/op  delta
CachedTGatherer_Update/Update_of_one_element_without_reset-12      3.00 ± 0%      3.00 ± 0%    0.00%
CachedTGatherer_Update/Update_of_all_elements_with_reset-12        0.00           0.00         0.00%
CachedTGatherer_Update/Gather-12                                  1.00k ± 0%     0.00k ± 0%  -99.60%

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Removed obsolete comment

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Fixed tests.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Removed cache.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Fixed tests.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Re-add cache.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Removed cache.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>
2022-02-23 11:22:52 +00:00
beorn7 e92283d644 Fix linter ignores
Signed-off-by: beorn7 <beorn@grafana.com>
2021-03-16 17:19:03 +01:00
debiandebiandebian 9443f4449b Fix typo in comments
Signed-off-by: debiandebiandebian <debiandebiandebiandebian@gmail.com>
2021-02-08 08:58:51 +09:00
beorn7 b54b73c7b1 Remove spurious commas from links to the docs site
I assume older Nanoc versions rendered the anchors with commas, but
the current doesn't.

Also, this adds the same link to another doc comment where it is also
relevant.

Signed-off-by: beorn7 <beorn@grafana.com>
2020-09-07 22:31:29 +02:00
beorn7 dba1478b8a Add lint:ignore for protobuf deprecation
`github.com/golang/protobuf/proto` is deprecated in lieu of
`google.golang.org/protobuf/proto`. However, we cannot simply
migrate. Types from the proto package are exposed to users of packages
in this repo. If we migrate here, users have to migrate to. Thus, we
could only migrate with a major version bump.

In different news, with all the inline lint:ignore comments, including
the existing ones, there is no need to repeat the exception in the
Makefile.

A current version of `staticcheck` is happy with the code after this
commit. golangci-lint is broken at the moment, however, and ignores
the lint:ignore comments in the code as well as those via envvar.

Signed-off-by: beorn7 <beorn@grafana.com>
2020-05-14 20:11:22 +02:00
beorn7 19af62dcc8 Use a cleaner initialization of `separatorByteSlice`
The `const separatorByte` wasn't used anymore actually. In `vec.go`,
we were using `model.SeparatorByte`, which is better anyway. So remove
the unused constant and initialize `separatorByteSlice` with
`model.SeparatorByte`, too.

Signed-off-by: beorn7 <beorn@grafana.com>
2019-10-15 19:52:31 +02:00
beorn7 ee1078a03c Move registry hashing to xxhash
This is a much stronger hash function than fnv64a and comparably fast
(with super-fast assembly implementation for amd64).

Performance is not critical here anyway.

The old fnv64a is kept for vectors, where collision detection is in
place and the weakness of the hashing doesn't matter that much. I
implemented a vector version with xxhash and found that xxhash is
slower in all cases except very very high cardinality (where it is
only slightly faster). Also, ``xxhash.New`` comes with an allocation
of 80 bytes. Thus, to keep vectors alloc-free, we needed to add a
`sync.Pool`, which would have an additional performance overhead.

Signed-off-by: beorn7 <beorn@grafana.com>
2019-10-14 21:18:38 +02:00
beorn7 663a9ad019 Make Help strings optional
This is in line with
https://prometheus.io/docs/instrumenting/writing_clientlibs/#metric-description-and-help

Since the zero value of a string in Go is `""`, we cannot distinguish
between a Help string not set and an empty Help string. Thus, we just
make it formally optional here with an encouragement to set it in the
doc comment.

In v0.10, the Help string will probably become a "normal" argument of
the constructor rather than a field in an Opts struct.

Signed-off-by: beorn7 <beorn@soundcloud.com>
2018-09-17 12:07:31 +02:00
beorn7 84d7aa0cd9 Add wrapping of Registerers with labels and prefix
Essentially middleware for Registerers!

Signed-off-by: beorn7 <beorn@soundcloud.com>
2018-09-12 15:34:07 +02:00
beorn7 da330f4281 Un-export prometheus.LabelPairSorter
The only known external usage of it was in prometheus/pushgateway,
where it was removed by
https://github.com/prometheus/pushgateway/pull/200 .

Originally, the expectation was that users would implement the Metric
interface now and then. As we know now, neither it is happening, nor
would it make a lot of sense. (Users implement the Collector interface
instead.) By now, LabelPairSorter is essentially noise in the already
quite cluttered namespace in the prometheus package.

Signed-off-by: beorn7 <beorn@soundcloud.com>
2018-09-03 16:20:55 +02:00
beorn7 abaece07d1 Fix import grouping
Signed-off-by: beorn7 <beorn@soundcloud.com>
2018-08-18 16:02:33 +02:00
beorn7 5240f7e8f5 Add a wrapper to add a timestamp to a metric
Signed-off-by: beorn7 <beorn@soundcloud.com>
2018-08-18 15:56:08 +02:00
Karsten Weiss 587d5265f8 metric.go: Remove unused type hashSorter
Fixes:
metric.go:130:6: type hashSorter is unused (U1000)

Signed-off-by: Karsten Weiss <knweiss@gmail.com>
2018-04-13 23:23:52 +02:00
beorn7 dd20712622 Allow currying of metric vec's
The idea behind it is described in detail in
https://github.com/prometheus/client_golang/issues/320 .

This commit also updates the example given in
promhttp/instrument_server_test.go , which nicely illustrates the
benefit of this change.

So far, currying could be emulated by creating different metric vec's
with different values in their ConstLabels. This was quite difficult
to grasp - which is essentially what was done in the example mentioned
above. Now that this use case can be solved without ConstLabels, we
can safely declare ConstLabels as rarely used. (Perhaps we can
deprecate them entirely one day, but I'll take a raincheck on that
when the changes of v0.10 have materialized.) This commit thus also
updates the ConstLabel doc comments in the various Opts. (It contained
fairly outdated stuff anyway.)
2017-12-22 15:56:11 +01:00
beorn7 a6321dd0b1 Create a "merge gatherer"
This allows to finally get rid of the infamous injection hook in the
interface. The old SetMetricFamilyInjectionHook still exist as a
deprecated function but is now implemented with the new plumbing under
the hood.

Now that we have multiple Gatherer implementation, I renamed
push.Registry to push.FromGatherer.

This commit also improves the consistency checks, which happened as a
byproduct of the refactoring to allow checking in both the "merge
gatherer" Gatherers as well as in the normal Registry.
2016-08-12 21:34:17 +02:00
beorn7 cf7e1caf17 Create a public registry interface and separate out HTTP exposition
General context and approch
===========================

This is the first part of the long awaited wider refurbishment of
`client_golang/prometheus/...`. After a lot of struggling, I decided
to not go for one breaking big-bang, but cut things into smaller steps
after all, mostly to keep the changes manageable and easy to
review. I'm aiming for having the invasive breaking changes
concentrated in as few steps as possible (ideally one). Some steps
will not be breaking at all, but typically there will be breaking
changes that only affect quite special cases so that 95+% of users
will not be affected. This first step is an example for that, see
details below.

What's happening in this commit?
================================

This step is about finally creating an exported registry
interface. This could not be done by simply export the existing
internal implementation because the interface would be _way_ too
fat. This commit introduces a qutie lean `Registry` interface
(compared to the previous interval implementation). The functions that
act on the default registry are retained (with very few exceptions) so
that most use cases won't see a change. However, several of those are
deprecated now to clean up the namespace in the future.

The default registry is kept in the public variable
`DefaultRegistry`. This follows the example of the http package in the
standard library (cf. `http.DefaultServeMux`, `http.DefaultClient`)
with the same implications. (This pattern is somewhat disputed within
the Go community but I chose to go with the devil you know instead of
creating something more complex or even disallowing any changes to the
default registry. The current approach gives everybody the freedom to
not touch DefaultRegistry or to do everything with a custom registry
to play save.)

Another important part in making the registry lean is the extraction
of the HTTP exposition, which also allows for customization of the
HTTP exposition. Note that the separation of metric collection and
exposition has the side effect that managing the MetricFamily and
Metric protobuf objects in a free-list or pool isn't really feasible
anymore. By now (with better GC in more recent Go versions), the
returns were anyway dimisishing. To be effective at all, scrapes had
to happen more often than GC cycles, and even then most elements of
the protobufs (everything excetp the MetricFamily and Metric structs
themselves) would still cause allocation churn. In a future breaking
change, the signature of the Write method in the Metric interface will
be adjusted accordingly. In this commit, avoiding breakage is more
important.

The following issues are fixed by this commit (some solved "on the
fly" now that I was touching the code anyway and it would have been
stupid to port the bugs):

https://github.com/prometheus/client_golang/issues/46
https://github.com/prometheus/client_golang/issues/100
https://github.com/prometheus/client_golang/issues/170
https://github.com/prometheus/client_golang/issues/205

Documentation including examples have been amended as required.

What future changes does this commit enable?
============================================

The following items are not yet implemented, but this commit opens the
possibility of implementing these independently.

- The separation of the HTTP exposition allows the implementation of
  other exposition methods based on the Registry interface, as known
  from other Prometheus client libraries, e.g. sending the metrics to
  Graphite.
  Cf. https://github.com/prometheus/client_golang/issues/197

- The public `Registry` interface allows the implementation of
  convenience tools for testing metrics collection. Those tools can
  inspect the collected MetricFamily protobufs and compare them to
  expectation. Also, tests can use their own testing instance of a
  registry.
  Cf. https://github.com/prometheus/client_golang/issues/58

Notable non-goals of this commit
================================

Non-goals that will be tackled later
------------------------------------

The following two issues are quite closely connected to the changes in
this commit but the line has been drawn deliberately to address them
in later steps of the refurbishment:

- `InstrumentHandler` has many known problems. The plan is to create a
  saner way to conveniently intrument HTTP handlers and remove the old
  `InstrumentHandler` altogether. To keep breakage low for now, even
  the default handler to expose metrics is still using the old
  `InstrumentHandler`. This leads to weird naming inconsistencies but
  I have deemed it better to not break the world right now but do it
  in the change that provides better ways of instrumenting HTTP
  handlers.
  Cf. https://github.com/prometheus/client_golang/issues/200

- There is work underway to make the whole handling of metric
  descriptors (`Desc`) more intuitive and transparent for the user
  (including an ability for less strict checking,
  cf. https://github.com/prometheus/client_golang/issues/47). That's
  quite invasive from the perspective of the internal code, namely the
  registry. I deliberately kept those changes out of this commit.

- While this commit adds new external dependency, the effort to vendor
  anything within the library that is not visible in any exported
  types will have to be done later.

Non-goals that _might_ be tackled later
---------------------------------------

There is a strong and understandable urge to divide the `prometheus`
package into a number of sub-packages (like `registry`, `collectors`,
`http`, `metrics`, …). However, to not run into a multitude of
circular import chains, this would need to break every single existing
usage of the library. (As just one example, if the ubiquitious
`prometheus.MustRegister` (with more than 2,000 uses on GitHub alone)
is kept in the `prometheus` package, but the other registry concerns
go into a new `registry` package, then the `prometheus` package would
import the `registry` package (to call the actual register method),
while at the same time the `registry` package needs to import the
`prometheus` package to access `Collector`, `Metric`, `Desc` and
more. If we moved `MustRegister` into the `registry` package,
thousands of code lines would have to be fixed (which would be easy if
the world was a mono repo, but it is not). If we moved everything else
the proposed registry package needs into packages of their own, we
would break thousands of other code lines.)

The main problem is really the top-level functions like
`MustRegister`, `Handler`, …, which effectively pull everything into
one package. Those functions are however very convenient for the easy
and very frequent use-cases.

This problem has to be revisited later.

For now, I'm trying to keep the amount of exported names in the
package as low as possible (e.g. I unexported expvarCollector in this
commit because the NewExpvarCollector constructor is enough to export,
and it is now consistent with other collectors, like the goCollector).

Non-goals that won't be tackled anytime soon
--------------------------------------------

Something that I have played with a lot is "streaming collection",
i.e. allow an implementation of the `Registry` interface that collects
metrics incrementally and serves them while doing so. As it has turned
out, this has many many issues and makes the `Registry` interface very
clunky. Eventually, I made the call that it is unlikely we will really
implement streaming collection; and making the interface more clunky
for something that might not even happen is really a big no-no. Note
that the `Registry` interface only creates the in-memory
representation of the metric family protobufs in one go. The
serializaton onto the wire can still be handled in a streaming fashion
(which hasn't been done so far, without causing any trouble, but might
be done in the future without breaking any interfaces).

What are the breaking changes?
==============================

- Signatures of functions pushing to Pushgateway have changed to allow
  arbitrary grouping (which was planned for a long time anyway, and
  now that I had to work on the Push code anyway for the registry
  refurbishment, I finally did it,
  cf. https://github.com/prometheus/client_golang/issues/100).
  With the gained insight that pushing to the default registry is almost
  never the right thing, and now that we are breaking the Push call
  anyway, all the Push functions were moved to their own package,
  which cleans up the namespace and is more idiomatic (pushing
  Collectors is now literally done by `push.Collectors(...)`).

- The registry is doing more consistency checks by default now. Past
  creators of inconsistent metrics could have masked the problem by
  not setting `EnableCollectChecks`. Those inconsistencies will now be
  detected. (But note that a "best effort" metrics collection is now
  possible with `HandlerOpts.ErrorHandling = ContinueOnError`.)

- `EnableCollectChecks` is gone. The registry is now performing some
  of those checks anyway (see previous item), and a registry with all
  of those checks can now be created with `NewPedanticRegistry` (only
  used for testing).

- `PanicOnCollectError` is gone. This behavior can now be configured
  when creating a custom HTTP handler.
2016-08-02 18:46:22 +02:00
Fabian Reinartz f2de0f589a Remove client_golang/model als direct dependency 2015-08-23 13:51:32 +02:00
Julius Volz 738b69e61a Use non-rewritten Godep imports. 2015-02-27 16:49:40 +01:00
Julius Volz 169c8a68e1 Use godep with import rewriting for vendoring.
The new vendoring was produced by running:

    godep save -r ./examples/... ./prometheus/... ./text/... ./model/... ./extraction/...

Two things to note:

- "extraction/processor0_0_{1,2}_test.go" imported a package from
  "github.com/prometheus/prometheus", all for just one tiny testing
  function. To not have to deal with a circular vendoring dependency, I
  simply replaced the usage of the function by some in-line logic.

- godep grouped the rewritten imports slightly differently for some
  reason, but at least the standard library imports are still in a
  separate section. Not sure if it's worth manually keeping our old
  import grouping scheme or if we should simply use that godep-generated
  one.
2015-02-26 00:47:03 +01:00
Bjoern Rabenstein d7f8eb1083 Change "Prometheus Team" to "The Prometheus Authors". 2015-02-02 15:14:36 +01:00
Bjoern Rabenstein 159e96f6c7 Allow error reporting during metrics collection and simplify Register().
Both are interface changes I want to get in before public
announcement. They only break rare usage cases, and are always easy to
fix, but still we want to avoid breaking changes after a wider
announcement of the project.

The change of Register() simply removes the return of the Collector,
which nobody was using in practice. It was just bloating the call
syntax. Note that this is different from RegisterOrGet(), which is
used at various occasions where you want to register something that
might or might not be registered already, but if it is, you want the
previously registered Collector back (because that's the relevant
one).

WRT error reporting: I first tried the obvious way of letting the
Collector methods Describe() and Collect() return error. However, I
had to conclude that that bloated _many_ calls and their handling in
very obnoxious ways. On the other hand, the case where you actually
want to report errors during registration or collection is very
rare. Hence, this approach has the wrong trade-off. The approach taken
here might at first appear clunky but is in practice quite handy,
mostly because there is almost no change for the "normal" case of "no
special error handling", but also because it plays well with the way
descriptors and metrics are handled (via channels).

Explaining the approach in more detail:

- During registration / describe: Error handling was actually already
  in place (for invalid descriptors, which carry an error anyway). I
  only added a convenience function to create an invalid descriptor
  with a given error on purpose.

- Metrics are now treated in a similar way. The Write method returns
  an error now (the only change in interface). An "invalid metric" is
  provided that can be sent via the channel to signal that that metric
  could not be collected. It alse transports an error.

NON-GOALS OF THIS COMMIT:

This is NOT yet the major improvement of the whole registry part,
where we want a public Registry interface and plenty of modular
configurations (for error handling, various auto-metrics, http
instrumentation, testing, ...). However, we can do that whole thing
without breaking existing interfaces. For now (which is a significant
issue) any error during collection will either cause a 500 HTTP
response or a panic (depending on registry config). Later, we
definitely want to have a possibility to skip (and only report
somehow) non-collectible metrics instead of aborting the whole scrape.
2015-01-12 19:16:09 +01:00
Bjoern Rabenstein 5d40912fd2 Complete rewrite of the exposition library.
This rewrite had may backs and forths. In my git repository, it
consists of 35 commits which I cannot group or merge into reasonable
review buckets. Gerrit breaks fundamental git semantics, so I have to
squash the 35 commits into one for the review.

I'll push this not with refs/for/master, but with refs/for/next so
that we can transition after submission in a controlled fashion.

For the review, I recommend to start with looking at godoc and in
particular the many examples. After that, continue with a line-by-line
detailed review. (The big picture is hopefully as expected after
wrapping up the discussion earlier.)

Change-Id: Ib38cc46493a5139ca29d84020650929d94cac850
2014-06-17 14:08:22 +02:00
Bernerd Schaefer 29ebb580db Add Reset(map[string]string) to Metric interface
Change-Id: I289cf8796adbd6ff55f23bba7730145329de00e1
2014-02-19 15:18:16 +01:00
Matt T. Proud 4956aea5ac Protocol Buffer negotiation support in handler. 2013-07-01 17:14:58 +02:00
Bernerd Schaefer 71dd60e431 Registry and Metrics implement json.Marshaler
* Drop `AsMarshallable()` from the Metric interface. Use
  `json.Marshaler` and `MarshalJSON()`, and leverage JSON struct tags
  where possible.

* Add `MarshalJSON()` to Registry and remove `dumpToWriter`, which
  makes the registry handler much simpler.

In addition to simplifying some of the marshalling behavior, this also
has the nice side effect of cutting down the number of
`map[string]interface{}` instances.
2013-04-19 15:07:24 +02:00
Matt T. Proud f320d28a6c Rearrange file and package per convention.
WIP - Please review but do not merge.
2013-04-04 15:27:09 +02:00