etcdserver: separate maybeCompactRaftLog function to compact raft log independently

[clement2026]

Part of #17098

Goal: separate maybeCompactRaftLog function to compact raft log independently from snapshots.

TODO

• [x] Add tests for the changes
• [x] https://github.com/etcd-io/etcd/issues/17098#issuecomment-2374327464
• [ ] https://github.com/etcd-io/etcd/pull/18637

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[k8s-ci-robot]

Hi @clement2026. Thanks for your PR.

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[clement2026]

@serathius Please take a look. This PR focuses on one task only.

[codecov-commenter]

Codecov Report

:x: Patch coverage is 76.66667% with 7 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 68.88%. Comparing base (59cfd7a) to head (841da6e). :warning: Report is 2079 commits behind head on main.

:warning: Current head 841da6e differs from pull request most recent head f34bee5

Please upload reports for the commit f34bee5 to get more accurate results.

Files with missing lines	Patch %	Lines
server/storage/wal/wal.go	71.42%	2 Missing and 2 partials :warning:
server/etcdserver/server.go	85.71%	1 Missing and 1 partial :warning:
server/storage/wal/file_pipeline.go	0.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

Files with missing lines	Coverage Δ
server/storage/wal/repair.go	56.14% <100.00%> (ø)
server/storage/wal/file_pipeline.go	90.69% <0.00%> (ø)
server/etcdserver/server.go	81.03% <85.71%> (-0.31%)	:arrow_down:
server/storage/wal/wal.go	57.73% <71.42%> (+0.27%)	:arrow_up:

... and 13 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #18635      +/-   ##
==========================================
+ Coverage   68.79%   68.88%   +0.08%     
==========================================
  Files         420      420              
  Lines       35522    35545      +23     
==========================================
+ Hits        24438    24485      +47     
+ Misses       9657     9639      -18     
+ Partials     1427     1421       -6     

---

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[clement2026]

I can't test ep.compacti directly because it's not accessible. However, I checked the logs and confirmed it’s working as expected.

Add log statements

	ep := etcdProgress{
		confState: sn.Metadata.ConfState,
		snapi:     sn.Metadata.Index,
		appliedt:  sn.Metadata.Term,
		appliedi:  sn.Metadata.Index,
		compacti:  fi - 1,
	}
	s.Logger().Info("initial ep.compacti", zap.Uint64("ep.compacti", ep.compacti),zap.Uint64("ep.snapi", ep.snapi))

	compacti := ep.snapi - s.Cfg.SnapshotCatchUpEntries
	if compacti <= ep.compacti {
		return
	}
	s.Logger().Info("compacti > ep.compacti", zap.Uint64("compacti", compacti), zap.Uint64("ep.compacti", ep.compacti))

Start a new etcd instance and make 110 put requests

➜  rm -rf default.etcd;  bin/etcd --experimental-snapshot-catchup-entries=5 --snapshot-count=10  2>&1 | grep 'ep.compacti'

➜ benchmark put --key-space-size=9999999 --val-size=100 --total=110

Logs:

{"level":"info","ts":"2024-09-24T23:38:10.660332+0800","caller":"etcdserver/server.go:823","msg":"initial ep.compacti","ep.compacti":0,"ep.snapi":0}
{"level":"info","ts":"2024-09-24T23:38:16.890460+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":6,"ep.compacti":0}
{"level":"info","ts":"2024-09-24T23:38:16.959513+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":17,"ep.compacti":6}
{"level":"info","ts":"2024-09-24T23:38:17.017577+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":28,"ep.compacti":17}
{"level":"info","ts":"2024-09-24T23:38:17.096548+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":39,"ep.compacti":28}
{"level":"info","ts":"2024-09-24T23:38:17.159693+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":50,"ep.compacti":39}
{"level":"info","ts":"2024-09-24T23:38:17.238754+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":61,"ep.compacti":50}
{"level":"info","ts":"2024-09-24T23:38:17.316651+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":72,"ep.compacti":61}
{"level":"info","ts":"2024-09-24T23:38:17.391588+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":83,"ep.compacti":72}
{"level":"info","ts":"2024-09-24T23:38:17.460776+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":94,"ep.compacti":83}
{"level":"info","ts":"2024-09-24T23:38:17.539552+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":105,"ep.compacti":94}
^C

Restart the etcd instance and make 50 put requests

➜  bin/etcd --experimental-snapshot-catchup-entries=5 --snapshot-count=10  2>&1 | grep 'ep.compacti'

➜ benchmark put --key-space-size=9999999 --val-size=100 --total=50

Logs:

{"level":"info","ts":"2024-09-24T23:38:24.076007+0800","caller":"etcdserver/server.go:823","msg":"initial ep.compacti","ep.compacti":110,"ep.snapi":110}
{"level":"info","ts":"2024-09-24T23:39:16.807112+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":116,"ep.compacti":110}
{"level":"info","ts":"2024-09-24T23:39:16.880017+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":127,"ep.compacti":116}
{"level":"info","ts":"2024-09-24T23:39:16.941133+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":138,"ep.compacti":127}
{"level":"info","ts":"2024-09-24T23:39:17.012076+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":149,"ep.compacti":138}
{"level":"info","ts":"2024-09-24T23:39:17.075207+0800","caller":"etcdserver/server.go:2195","msg":"compacti > ep.compacti","compacti":160,"ep.compacti":149}

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[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed after 21 days if no further activity occurs. Thank you for your contributions.