Merge release-1.12 branch back into main (#1079)

* Cut v1.12.0

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Bump the day

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Make the Go 1.17 collector thread-safe (#969)

* Use simpler locking in the Go 1.17 collector (#975)

A previous PR made it so that the Go 1.17 collector locked only around
uses of rmSampleBuf, but really that means that Metric values may be
sent over the channel containing some values from future metrics.Read
calls. While generally-speaking this isn't a problem, we lose any
consistency guarantees provided by the runtime/metrics package.

Also, that optimization to not just lock around all of Collect was
premature. Truthfully, Collect is called relatively infrequently, and
its critical path is fairly fast (10s of µs). To prove it, this change
also adds a benchmark.

name            old time/op  new time/op  delta
GoCollector-16  43.7µs ± 2%  43.2µs ± 2%   ~     (p=0.190 n=9+9)

Note that because the benchmark is single-threaded it actually looks
like it might be getting *slightly* faster, because all those Collect
calls for the Metrics are direct calls instead of interface calls.

Signed-off-by: Michael Anthony Knyszek <mknyszek@google.com>

* API client: make http reads more efficient (#976)

Replace `io.ReadAll` with `bytes.Buffer.ReadFrom`.
Both need to resize a buffer until they have finished reading;
the former increases by 1.25x each time while the latter uses 2x.

Also added a benchmark to demonstrate the benefit:
name             old time/op    new time/op    delta
Client/4KB-8       35.9µs ± 4%    35.3µs ± 3%     ~     (p=0.310 n=5+5)
Client/50KB-8      83.1µs ± 8%    69.5µs ± 1%  -16.37%  (p=0.008 n=5+5)
Client/1000KB-8     891µs ± 6%     750µs ± 0%  -15.83%  (p=0.016 n=5+4)
Client/2000KB-8    1.74ms ± 2%    1.35ms ± 1%  -22.72%  (p=0.008 n=5+5)

name             old alloc/op   new alloc/op   delta
Client/4KB-8       20.2kB ± 0%    20.4kB ± 0%   +1.26%  (p=0.008 n=5+5)
Client/50KB-8       218kB ± 0%     136kB ± 0%  -37.65%  (p=0.008 n=5+5)
Client/1000KB-8    5.88MB ± 0%    2.11MB ± 0%  -64.10%  (p=0.008 n=5+5)
Client/2000KB-8    11.7MB ± 0%     4.2MB ± 0%  -63.93%  (p=0.008 n=5+5)

name             old allocs/op  new allocs/op  delta
Client/4KB-8         75.0 ± 0%      72.0 ± 0%   -4.00%  (p=0.008 n=5+5)
Client/50KB-8         109 ± 0%        98 ± 0%  -10.09%  (p=0.079 n=4+5)
Client/1000KB-8       617 ± 0%       593 ± 0%   -3.89%  (p=0.008 n=5+5)
Client/2000KB-8     1.13k ± 0%     1.09k ± 0%   -3.27%  (p=0.008 n=5+5)

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

* Reduce granularity of histogram buckets for Go 1.17 collector (#974)

The Go runtime/metrics package currently exports extremely granular
histograms. Exponentially bucket any histogram with unit "seconds"
or "bytes" instead to dramatically reduce the number of buckets, and
thus the number of metrics.

This change also adds a test to check for expected cardinality to
prevent cardinality surprises in the future.

Signed-off-by: Michael Anthony Knyszek <mknyszek@google.com>

* Cut v1.12.1 (#978)

* Cut v1.12.1

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Apply review suggestions

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Fix deprecated `NewBuildInfoCollector` API

Update `examples/random/main.go`:
  `prometheus.NewBuildInfoCollector` is deprecated. Use `collectors.NewBuildInfoCollector` instead.

Signed-off-by: alissa-tung <alissa-tung@outlook.com>

* gocollector: Added options to Go Collector for changing the (#1031)

* Renamed files.

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

* gocollector: Added options to Go Collector for diffetent collections.

Fixes #983

Also:

* fixed TestMemStatsEquivalence, it was noop before (:
* Removed gc_cpu_fraction metric completely, since it's not working completely for Go1.17+

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

* gocollector: Reverted client_golang v1.12 addition of runtime/metrics metrics by default. (#1033)

Fixes #967

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

* prometheus: Fix convention violating names for generated collector metrics (#1048)

* Fix convention violating names for generated collector metrics

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Add new Go collector example

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Remove -Inf buckets from go collector histograms (#1049)

* Remove -Inf buckets from go collector histograms

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Update prometheus/collectors/go_collector_latest_test.go

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Simplify

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

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

* Cut v1.12.2 (#1052)

* Cut v1.12.2

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Apply suggestions

Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

* Update CHANGELOG.md

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Signed-off-by: Kemal Akkoyun <kakkoyun@gmail.com>

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

Co-authored-by: Kemal Akkoyun <kakkoyun@gmail.com>
Co-authored-by: Michael Knyszek <mknyszek@google.com>
Co-authored-by: Bryan Boreham <bjboreham@gmail.com>
Co-authored-by: Kemal Akkoyun <kakkoyun@users.noreply.github.com>
Co-authored-by: alissa-tung <alissa-tung@outlook.com>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>