statistics: add metrics for statscache lru

[Yisaer]

Signed-off-by: yisaer [email protected]

What problem does this PR solve?

Issue Number: ref #34052

What is changed and how it works?

add metrics for statscache lru

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• hawkingrei
• xuyifangreeneyes

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[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/87c172d7b009c9766fcc01191d5374a7ca3fd8ce

[xuyifangreeneyes]

Why do set costGauge here?

tidb/statistics/handle/handle.go

Lines 544 to 554 in 145058c

	func (h *Handle) updateStatsCache(newCache statsCache) (updated bool) {
	h.statsCache.Lock()
	oldCache := h.statsCache.Load().(statsCache)
	if oldCache.version < newCache.version || (oldCache.version == newCache.version && oldCache.minorVersion < newCache.minorVersion) {
	h.statsCache.memTracker.Consume(newCache.Cost() - oldCache.Cost())
	h.statsCache.Store(newCache)
	updated = true
	}
	h.statsCache.Unlock()
	return
	}

oldCache.Cost() seems to affect cost tracking?

[Yisaer]

nice catch, updated.

[Yisaer]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 336b7f4

[Yisaer]

/run-mysql-test

[sre-bot]

TiDB MergeCI notify

CI Name	Result	Duration	Compare with Parent commit
idc-jenkins-ci/integration-cdc-test	🟢 all 34 tests passed	27 min	Existing passed
idc-jenkins-ci-tidb/integration-common-test	🟢 all 11 tests passed	11 min	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-2	🟢 all 28 tests passed	8 min 40 sec	Existing passed
idc-jenkins-ci-tidb/common-test	🟢 all 12 tests passed	6 min 49 sec	Existing passed
idc-jenkins-ci-tidb/integration-ddl-test	🟢 all 6 tests passed	6 min 39 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-1	🟢 all 26 tests passed	5 min 47 sec	Existing passed
idc-jenkins-ci-tidb/tics-test	🟢 all 1 tests passed	5 min 29 sec	Existing passed
idc-jenkins-ci-tidb/mybatis-test	🟢 all 1 tests passed	4 min 21 sec	Existing passed
idc-jenkins-ci-tidb/integration-compatibility-test	🟢 all 1 tests passed	2 min 58 sec	Existing passed
idc-jenkins-ci-tidb/plugin-test	🟢 build success, plugin test success	4min	Existing passed