Fix streak length metric reporting

[Tom-Newton]

Tracking issue

Closes #5170

Why are the changes needed?

Accurate metrics are useful.

What changes were proposed in this pull request?

Fix the streak length metric reporting by avoiding use of defer. Included slightly simplifying the branching logic.

How was this patch tested?

I've been using it in production.

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly - not applicable
• All new and existing tests passed
• All commits are signed-off.

Related PRs

Docs link

[eapolinario]

Golang's defer semantics allows us to use this idiom with a slight change. From the spec:

Each time a "defer" statement executes, the function value and parameters to the call are evaluated as usual and saved anew but the actual function is not invoked.

This means that we can define a function that closes over streak like so:

defer func() { p.metrics.StreakLength.Add(ctx, float64(streak)) }()

[Tom-Newton]

Done. As you can probably tell I don't really know what I'm doing with golang 😅

[Tom-Newton]

I rebased on latest master, which I'm hoping will fix the docs build error

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.06%. Comparing base (f1c2231) to head (e0a414a).
Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5172      +/-   ##
==========================================
- Coverage   59.06%   59.06%   -0.01%     
==========================================
  Files         646      646              
  Lines       55714    55725      +11     
==========================================
+ Hits        32910    32915       +5     
- Misses      20208    20214       +6     
  Partials     2596     2596              

Flag	Coverage Δ
unittests	59.06% <100.00%> (-0.01%)	⬇️

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[Tom-Newton]

Pretty sure I fixed the linter error. Initially I struggled a bit to run linting locally.