event: add a namespace to every event

Add a namespace to every event.

It can be set with Builder.Namespace.

By default we use the import path of the package that builds the
event.

The Exporter memoizes the map from pcs to namespaces. This saves both
the time to extract the frame and parse the fully-qualified function
name, and the allocation that is inevitable because
runtime.CallersFrames takes a slice.

This is significantly slower in the Noop cases (see below), so the
user must enable it with an option.

name                  old time/op    new time/op    delta
LogEventNoExporter-8     616ns ± 2%     612ns ± 2%    -0.67%  (p=0.019 n=17+20)
LogEventNoop-8          1.83µs ± 3%   13.51µs ± 4%  +638.00%  (p=0.000 n=18+19)
LogEventDiscard-8       10.7µs ± 2%    23.7µs ± 2%  +121.35%  (p=0.000 n=20+17)
LogEventfDiscard-8      16.6µs ± 2%    28.8µs ± 1%   +73.47%  (p=0.000 n=19+18)
TraceEventNoop-8        41.5µs ± 3%    78.6µs ± 1%   +89.63%  (p=0.000 n=19+18)
MetricEventNoop-8       16.4µs ± 2%    40.9µs ± 2%  +149.97%  (p=0.000 n=17+20)
Logrus-8                55.4µs ± 2%    54.3µs ± 3%    -1.97%  (p=0.000 n=19+17)
Logrusf-8               46.4µs ± 3%    45.1µs ± 1%    -2.82%  (p=0.000 n=20+18)
Baseline-8               280ns ± 2%     278ns ± 2%    -0.72%  (p=0.025 n=19+20)
LogStdlib-8             8.54µs ± 1%    8.49µs ± 2%    -0.60%  (p=0.043 n=18+18)
LogPrintf-8             13.1µs ± 2%    13.0µs ± 2%    -0.72%  (p=0.010 n=18+18)
LogZap-8                20.4µs ± 3%    20.1µs ± 1%    -1.43%  (p=0.000 n=20+18)
LogZapf-8               21.7µs ± 3%    21.6µs ± 1%      ~     (p=0.797 n=20+19)
LogZerolog-8            7.47µs ± 2%    7.40µs ± 1%    -0.87%  (p=0.006 n=18+19)
LogZerologf-8           12.5µs ± 3%    12.6µs ± 2%      ~     (p=0.171 n=18+19)

Further testing showed that the time is all due to runtime.Callers;
caching the pcs is very effective at eliminating any overhead from
extracting frame information.  (Note that TraceEventNoop and
MetricEventNoop are misnamed; they install a printer that writes to
io.Discard.)

Change-Id: I37bb5e6194be6dcaaa471086dcd3d4850bfd531c
Reviewed-on: https://go-review.googlesource.com/c/exp/+/324291
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
4 files changed
tree: 900d9049d3189e636432e94050bcc54d09bec095
  1. .gitattributes
  2. .gitignore
  3. AUTHORS
  4. CONTRIBUTING.md
  5. CONTRIBUTORS
  6. LICENSE
  7. PATENTS
  8. README.md
  9. apidiff/
  10. cmd/
  11. codereview.cfg
  12. ebnf/
  13. ebnflint/
  14. errors/
  15. event/
  16. fsnotify/
  17. go.mod
  18. go.sum
  19. inotify/
  20. io/
  21. mmap/
  22. rand/
  23. shiny/
  24. shootout/
  25. sumdb/
  26. utf8string/
  27. winfsnotify/
README.md

exp

PkgGoDev

This subrepository holds experimental and deprecated (in the old directory) packages.

The idea for this subrepository originated as the pkg/exp directory of the main repository, but its presence there made it unavailable to users of the binary downloads of the Go installation. The subrepository has therefore been created to make it possible to go get these packages.

Warning: Packages here are experimental and unreliable. Some may one day be promoted to the main repository or other subrepository, or they may be modified arbitrarily or even disappear altogether.

In short, code in this subrepository is not subject to the Go 1 compatibility promise. (No subrepo is, but the promise is even more likely to be violated by go.exp than the others.)

Caveat emptor.