Invalidate read-index cache when lock is found (#11016)

[ti-chi-bot]

This is an automated cherry-pick of #11016

What problem does this PR solve?

Issue Number: close #10985

Problem Summary:

When TiFlash local learner read meets a lock, the read-index result for that region may still be cached. Later retries can reuse the old read-index result even though the lock needs a newer apply progress to be resolved, which can cause unnecessary remote reads or repeated lock handling.

What is changed and how it works?

Invalidate read index cache when lock is found
Print first lock info in lock exception

This PR invalidates the read-index cache when a local lock is found, so later retries need to obtain a fresh read-index result for that region.

It also prints the first lock's detailed info in LockException, making it easier to identify the blocking lock from TiFlash logs without dumping every lock.

Check List

Tests

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

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

Fix the issue that TiFlash may reuse stale read-index cache after meeting a local lock.

Summary by CodeRabbit

• Bug Fixes

  • Improved read consistency by clearing cached read-index results when lock resolution detects a conflicting lock.
  • Reduced the risk of stale commit-index data being returned for affected regions.
  • Enhanced lock-related error messages with first-lock details and additional debugging information.
  • Ensured related cached query results are refreshed after invalidation.

• Tests

  • Added coverage confirming invalidated read-index data refreshes and reflects the latest commit index.

[coderabbitai]

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gengliqi, JaySon-Huang

The full list of commands accepted by this bot can be found here.

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Details

Needs approval from an approver in each of these files:

• OWNERS [JaySon-Huang,gengliqi]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-08-10 12:17:40.942345487 +0000 UTC m=+3048846.978440543: ☑️ agreed by JaySon-Huang.
• 2026-08-11 03:58:41.408693094 +0000 UTC m=+3105307.444788150: ☑️ agreed by gengliqi.