commit 368a25b2f0c9ccbda5f31d04e6df9f23e294b8b0
author Jonathan Amsterdam <jba@google.com> Wed Jun 09 07:17:19 2021 -0400
committer Jonathan Amsterdam <jba@google.com> Thu Jun 10 11:50:08 2021 +0000
tree 94de84485e6f4fda09dd2934f52c30273429cd7a
parent 8a7358d1686588689ef59e61e3382115c0cc301f

event: metric-specific builders

This CL imagines that each kind of metric is its own type, and has its
own builder.

Notes:

- Metric values are checked by the language. For example, we can enforce that
  counter values are unsigned integers.
  That means, however, that we either have to provide metric types for each common
  value type, or we have to wait for generics to allow a variety of types.

- Builder methods can be tailored to metrics. For example, metric
  builders have no way to override the metric's namespace. But it's
  not clear that's the right choice, and I think that's the only
  method that we might want to omit.

- In theory, users can define their own metric types. In practice,
  they'd have to duplicate a lot of our unexported machinery, or we'd
  have to export it somehow.

- You can't add common labels to a single Builder and re-use that builder
  for both metrics and other events.

Change-Id: Ie99cb3b953e1670fb8d6910f9412885e5dcbc219
Reviewed-on: https://go-review.googlesource.com/c/exp/+/326289
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>