event: changes to support context in start

Start now has a fluent builder, this makes constructing start events conceptually the same as all other types.
It also allows the span builder to carry the context, which is then passed to the handler.
Handler now has a method per kind rather than a single Handle method, and Kind has been removed from event.
This (amongst other things) allows Start to have a different signature so it can take and return a context.
It is also the fastest implementation so far across all benchmarks.
Disabled is now implemented by build tag instead of boolean.

Change-Id: Id00a22633a35bfaccf20ea5fcc1f918f849411fd
Reviewed-on: https://go-review.googlesource.com/c/exp/+/319070
Trust: Ian Cottrell <iancottrell@google.com>
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
18 files changed
tree: 6df884b1d8e7234472d6bf0d53fba1ae8d5842bb
  1. .gitattributes
  2. .gitignore
  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/



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.