Combine hit and miss cache metrics into single tagged metric

[pkoenig10]

We already broke the cache.hit and cache.miss metrics when we changed them to meters in #1897. We can take this opportunity to improve these metrics by combining them into a single cache.request metric tagged by result.

This makes it easier for consumers to make queries for things like the total number of requests or the hit rate, without having to know/assume that "requests = hits + misses".

[changelog-app]

Generate changelog in changelog/@unreleased

What do the change types mean?

• feature: A new feature of the service.
• improvement: An incremental improvement in the functionality or operation of the service.
• fix: Remedies the incorrect behaviour of a component of the service in a backwards-compatible way.
• break: Has the potential to break consumers of this service's API, inclusive of both Palantir services
  and external consumers of the service's API (e.g. customer-written software or integrations).
• deprecation: Advertises the intention to remove service functionality without any change to the
  operation of the service itself.
• manualTask: Requires the possibility of manual intervention (running a script, eyeballing configuration,
  performing database surgery, ...) at the time of upgrade for it to succeed.
• migration: A fully automatic upgrade migration task with no engineer input required.

Note: only one type should be chosen.

How are new versions calculated?

• ❗The break and manual task changelog types will result in a major release!
• 🐛 The fix changelog type will result in a minor release in most cases, and a patch release version for patch branches. This behaviour is configurable in autorelease.
• ✨ All others will result in a minor version release.

Type

• Feature
• Improvement
• Fix
• Break
• Deprecation
• Manual task
• Migration

Description

The cache.hit and cache.miss metrics have been combined into a single cache.request metric tagged by result.

Check the box to generate changelog(s)

• Generate changelog entry

[pkoenig10]

This is unused

[schlosna]

Agree that hit/miss tag makes metric easier to consume, will just need to update some dashboards anyway

Invalidated by push of 92a0ac1

[pkoenig10]

@carterkozak @schlosna can I get another +1? Looks like the changelog commit invalidated the approval.

[svc-autorelease]

Released 0.87.0

[schlosna]

@carterkozak @schlosna can I get another +1? Looks like the changelog commit invalidated the approval.

👍

We should figure out if policybot should be invalidating on changelog

[pkoenig10]

I suspect we do this for our open source repos because commits may be authored by non-Palantir contributors.