add txsSyncDurationTotal counter

[karknu]

Description

Add a txsSyncDurationTotal counter for tracking the total time spent syncing the mempool.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Running tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-9.6 and ghc-9.12
• Self-reviewed the diff

Note on CI

If your PR is from a fork, the necessary CI jobs won't trigger automatically for security reasons.
You will need to get someone with write privileges. Please contact IOG node developers to do this
for you.

[nfrisby]

LGTM

My only experience with the counters was from implementing this commit January 9afc1e7

So I primarily just compared to that. The only difference I'm seeing is that this counter would not be maintained when the Mempool tracer is turned off. I think that's probably fine. (But happened to not be something we wanted for the January commit.)

I hesitate to Approve, only because I don't own this repository. But if someone who owns it feels comfortable to Approve based on this Comment, feel free.

[nfrisby]

For reference, I looked this up (for the nth time) just to check: Nothing is increment and Just n is +n

https://github.com/IntersectMBO/hermod-tracing/blob/0af5e41f81a6463a53b9ea109d85436b014de40e/trace-dispatcher/src/Cardano/Logging/Tracer/EKG.hs#L83-L84

[nfrisby]

EKG counters are integral. I think it's fine to round to milliseconds before contributing to the running total.

[nfrisby]

Matches mapForgingStatsTxsProcessed just above ✅

[karknu]

So I primarily just compared to that. The only difference I'm seeing is that this counter would not be maintained when the Mempool tracer is turned off. I think that's probably fine.

I implemented it like the txsProcessedNum counter. It and the other mempool counters/gauges have the same behavior where they depend on the tracer being enabled.

[jutaro]

No findings.

The new txsSyncDurationTotal metric looks consistent with the existing tracing/metrics pattern, and the naming/help-text updates match the behavior. Residual risk: I did not see tests for the new counter, so runtime/exporter behavior should still be checked manually.