[Timelock Partitioning] Part 32: Client aware event recorders

[felixdesouza]

Goals (and why):
As part of leadership paxos, there is the LeadershipEventRecorder which tracks metrics on leadership events and notifies any observers. Such metrics should be tagged with the client.

Implementation Description (bullets):

• Rely on hierarchical TaggedMetricRegistry which has client populated in it already
• Downside is that we don't get this for logs, toyed with the idea of using a Proxy, that would append a client for the logger calls, but that feels fragile and easy to forget, so just ended up passing in a list of safe args that will be additionally logged.

Testing (What was existing testing like? What have you done to improve it?):
Removed smoke tests that are no longer applicable, not particularly valuable + we can't get tagged metrics out of dropwizard.

Concerns (what feedback would you like?):

• This is a break for large internal product, but should be a fairly minor one that I can fix up.

Priority (whenever / two weeks / yesterday):
🚒

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Type

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

Description

PaxosLeadershipEventRecorder now takes in a TaggedMetricRegistry instead of a MetricRegistry. The names of the metrics remain the same.

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[jeremyk-91]

Looks good - though one question: it doesn't look like we pass in the client arg yet?

[jeremyk-91]

Would still be good to look at the naming suggestions, but otherwise this looks good!