expression: refactor cache logic for builtinRegexpSubstrFuncSig

[lcwangchao]

What problem does this PR solve?

Issue Number: close #49583

Problem Summary:

See #49583 and #49464

What changed and how does it work?

1. Add CtxID to StatementContext to return a unique ID for statement context.
2. Introduce builtinFuncCache to provide a cache mechanism for built function. It uses context ID to separate cache between different statements so that we can still cache some immediate states even if plan cache is enabled now.
3. Introduce regexpNewBaseFuncSig as a new base for regex related functions. We'll use regexpNewBaseFuncSig to replace the old regexpBaseFuncSig in the next several PRs.
4. refactor builtinRegexpSubstrFuncSig to use regexpNewBaseFuncSig to manage the cache, so that:

• It's implement can decouple with plan cache
• It can still cache the parsed *regexp.Regexp when plan cache is on and regex pattern is read from a variable

Check List

Tests

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

  • I checked and no code files have been changed.

We did a benchmark test and the performance of regexp_substr increased:

func BenchmarkRegexpSubStr(b *testing.B) {
	store := testkit.CreateMockStore(b)
	tk := testkit.NewTestKit(b, store)
	tk.MustExec("use test")
	tk.MustExec("create table t(a varchar(256))")
	for i := 0; i < b.N; i++ {
		tk.MustExec(fmt.Sprintf("insert into t values('pingcaper%d@pingcap.com')", i))
	}
	tk.MustExec(`set @regexp='^\\w+([-+.]\\w+)*@\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*$'`)
	tk.MustExec("prepare s from 'select regexp_substr(a, ?) from t'")

	b.ResetTimer()
	tk.MustQuery("execute s using @regexp")
	b.StopTimer()
}

Master:

go test -bench='^BenchmarkRegexpSubStr$' -run='^$' -benchtime=1000000x --tags=intest
...
 1000000	      1804 ns/op
PASS
ok  	github.com/pingcap/tidb/pkg/expression/integration_test	64.611s

This PR:

go test -bench='^BenchmarkRegexpSubStr$' -run='^$' -benchtime=1000000x --tags=intest
...
 1000000	       333.3 ns/op
PASS
ok  	github.com/pingcap/tidb/pkg/expression/integration_test	64.772s

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

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

improve the performance of function `regexp_substr` in some cases when plan cache enabled

[codecov]

Codecov Report

Merging #49584 (0879ea0) into master (fb9d220) will increase coverage by 0.5730%.
Report is 26 commits behind head on master.
The diff coverage is 63.8888%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #49584        +/-   ##
================================================
+ Coverage   71.0039%   71.5769%   +0.5730%     
================================================
  Files          1368       1423        +55     
  Lines        399378     420521     +21143     
================================================
+ Hits         283574     300996     +17422     
- Misses        96012     100609      +4597     
+ Partials      19792      18916       -876     

Flag	Coverage Δ
integration	43.8174% <63.8888%> (?)
unit	71.0041% <ø> (+0.0002%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9663% <ø> (ø)
parser	∅ <ø> (∅)
br	47.2731% <ø> (-5.6218%)	⬇️

[lcwangchao]

/retest

[lcwangchao]

/retest

[xzhangxian1008]

Why we double check the cache outside of the lock protection?

[lcwangchao]

To achieve a better performance, ensure a concurrent call of getOrInitCache will not block each other.

[YangKeao]

LGTM

[xzhangxian1008]

LGTM

[ti-chi-bot]

@xzhangxian1008: adding LGTM is restricted to approvers and reviewers in OWNERS files.

In response to this:

LGTM

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: XuHuaiyu, xzhangxian1008, YangKeao

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Needs approval from an approver in each of these files:

• OWNERS [XuHuaiyu,YangKeao]
• pkg/expression/OWNERS [XuHuaiyu]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-12-20 09:20:53.99525382 +0000 UTC m=+1039145.032480749: ☑️ agreed by YangKeao.
• 2023-12-20 10:09:08.225141316 +0000 UTC m=+1042039.262368243: ☑️ agreed by XuHuaiyu.