txn: support shared lock for pessimistic / prewrite / commit schedulers by you06 · Pull Request #19282 · tikv/tikv

you06 · 2026-01-13T10:57:47Z

What is changed and how it works?

Issue Number: ref #19087

What's Changed:

This PR implement the acquire_pessimistic_lock / prewrite / commit schedulers for shared lock.

Related changes

PR to update pingcap/docs/pingcap/docs-cn:
Need to cherry-pick to the release branch

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

Release note

None

Copilot

Pull request overview

This pull request implements support for shared locks in the pessimistic transaction model for TiKV. The PR adds shared lock functionality to the acquire_pessimistic_lock, prewrite, and commit schedulers/actions.

Changes:

Adds SharedLock variant to Mutation enum and related type handling
Implements shared lock acquisition logic in acquire_pessimistic_lock action
Updates prewrite logic to handle shared lock mutations and merge them with existing shared locks
Modifies commit logic to handle shared lock entries, removing locks individually while keeping remaining entries
Adds scheduler support for tracking whether lock requests are for shared locks
Implements SharedLocks type with methods for managing multiple transaction locks on the same key

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
components/txn_types/src/types.rs	Adds SharedLock mutation type and helper methods
components/txn_types/src/lock.rs	Implements SharedLocks structure with lock management methods and for_update_ts tracking
components/txn_types/src/lib.rs	Exports SharedLocks type
src/storage/txn/actions/acquire_pessimistic_lock.rs	Refactors lock acquisition to handle shared locks, adds helper functions for existing lock types
src/storage/txn/actions/prewrite.rs	Updates prewrite to handle shared lock mutations, validates incompatibilities with async commit/1PC
src/storage/txn/actions/commit.rs	Modifies commit to remove individual locks from shared lock entries
src/storage/txn/commands/mod.rs	Adds is_shared_lock_request field to WriteResultLockInfo
src/storage/txn/commands/acquire_pessimistic_lock.rs	Passes shared lock flag through command execution
src/storage/txn/commands/acquire_pessimistic_lock_resumed.rs	Updates resumed command to pass shared lock flag
src/storage/txn/commands/prewrite.rs	Updates byte size calculation to include SharedLock mutations
src/storage/txn/commands/flush.rs	Updates byte size calculation to include SharedLock mutations
src/storage/txn/scheduler.rs	Refactors pessimistic lock cleanup logic with better scoping
src/storage/mvcc/txn.rs	Adds put_shared_lock and put_shared_pessimistic_lock methods
src/storage/mvcc/mod.rs	Exports SharedLocks and adds test helper function
src/storage/mvcc/metrics.rs	Adds metric for shared lock acquisition
src/storage/mvcc/reader/reader.rs	Updates test to pass new shared lock parameter
tests/failpoints/cases/test_storage.rs	Adds comprehensive integration test for shared/exclusive lock conflicts

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src/storage/txn/actions/prewrite.rs

components/txn_types/src/lock.rs

tests/failpoints/cases/test_storage.rs

src/storage/txn/actions/acquire_pessimistic_lock.rs

src/storage/mvcc/txn.rs

src/storage/txn/actions/commit.rs

Signed-off-by: you06 <you1474600@gmail.com>

you06 · 2026-01-14T08:13:17Z

/retest

Copilot

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

tests/failpoints/cases/test_storage.rs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Signed-off-by: you06 <you1474600@gmail.com>

Signed-off-by: you06 <you1474600@gmail.com> update type hint Signed-off-by: you06 <you1474600@gmail.com> update kvproto Signed-off-by: you06 <you1474600@gmail.com> fix: adapt into_lock_info for current branch design The cherry-picked PR had Lock::into_lock_info handling LockType::Shared, but in the current branch Lock and SharedLocks are separate types. This commit: - Simplifies Lock::into_lock_info to panic on LockType::Shared (shouldn't happen) - Updates SharedLocks::into_lock_info to properly set SharedPessimisticLock/SharedLock types Signed-off-by: you06 <you1474600@gmail.com> fix lock type Signed-off-by: you06 <you1474600@gmail.com>

cfzjywxk · 2026-01-15T02:33:30Z

src/storage/txn/actions/acquire_pessimistic_lock.rs

    // do it when val exists
-    if !lock_only_if_exists || val.is_some() {
+    if is_shared_lock_req {
+        txn.put_shared_pessimistic_lock(key, current_shared_locks, lock);


Would the other path like cleanup.rs, scan_locks panic because of LockType::Shared is unimplemented! for them by now?

If there is a shared lock in the storage engine, some unimplemented! will panic. But no client can write shared locks by now.

src/storage/mvcc/txn.rs

Signed-off-by: you06 <you1474600@gmail.com>

zyguan · 2026-01-15T09:28:53Z

/retest

Signed-off-by: you06 <you1474600@gmail.com>

ti-chi-bot · 2026-01-20T11:42:36Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cfzjywxk, zyguan

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ti-chi-bot · 2026-01-20T11:42:39Z

[LGTM Timeline notifier]

Timeline:

2026-01-16 06:24:38.459903742 +0000 UTC m=+129506.073860598: ☑️ agreed by zyguan.
2026-01-20 11:42:37.519597781 +0000 UTC m=+494185.133554637: ☑️ agreed by cfzjywxk.

…rs (tikv#19282) ref tikv#19087 This PR implement the acquire_pessimistic_lock / prewrite / commit schedulers for shared lock. Signed-off-by: you06 <you1474600@gmail.com>

ref tikv#19087 Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>

ti-chi-bot · 2026-03-04T08:03:39Z

In response to a cherrypick label: new pull request created to branch release-8.5: #19423.
But this PR has conflicts, please resolve them!

…rs (tikv#19282) ref tikv#19087 This PR implement the acquire_pessimistic_lock / prewrite / commit schedulers for shared lock. Signed-off-by: you06 <you1474600@gmail.com>

…rs (#19282) (#19423) ref #19087 This PR implement the acquire_pessimistic_lock / prewrite / commit schedulers for shared lock. Signed-off-by: you06 <you1474600@gmail.com> Co-authored-by: you06 <you1474600@gmail.com>

Copilot AI review requested due to automatic review settings January 13, 2026 10:57

ti-chi-bot bot added release-note-none Denotes a PR that doesn't merit a release note. dco-signoff: yes Indicates the PR's author has signed the dco. size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. labels Jan 13, 2026

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you06 added 2 commits January 13, 2026 22:38

cherry pick tikv#19110 to master

5930cd1

Signed-off-by: you06 <you1474600@gmail.com>

fix build & test

57dab48

Signed-off-by: you06 <you1474600@gmail.com>

you06-pingcap force-pushed the master-shared-lock/schedulers-1 branch from 4858a0d to 57dab48 Compare January 13, 2026 16:44

you06 added 3 commits January 14, 2026 12:52

fix tests & remove redundant code

81bf708

Signed-off-by: you06 <you1474600@gmail.com>

clean code

a2d363f

Signed-off-by: you06 <you1474600@gmail.com>

update

65f4d6b

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you06 requested a review from Copilot January 14, 2026 06:55

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tests/failpoints/cases/test_storage.rs Outdated Show resolved Hide resolved

you06 and others added 2 commits January 14, 2026 18:08

Update tests/failpoints/cases/test_storage.rs

11860f2

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Signed-off-by: you06 <you1474600@gmail.com>

cfzjywxk reviewed Jan 15, 2026

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you06 added 4 commits January 15, 2026 16:11

address comment

fbdf346

Signed-off-by: you06 <you1474600@gmail.com>

format

77fd990

Signed-off-by: you06 <you1474600@gmail.com>

Merge branch 'master' into master-shared-lock/schedulers-1

2cf12d0

Signed-off-by: you06 <you1474600@gmail.com>

fix SharedLocks usage

75587ab

Signed-off-by: you06 <you1474600@gmail.com>

you06 added 3 commits January 15, 2026 20:50

fix test

c6b7078

Signed-off-by: you06 <you1474600@gmail.com>

format code

1bf8b66

Signed-off-by: you06 <you1474600@gmail.com>

fix test

a2f0e7b

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zyguan approved these changes Jan 16, 2026

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ti-chi-bot bot added needs-1-more-lgtm Indicates a PR needs 1 more LGTM. approved labels Jan 16, 2026

you06 requested a review from cfzjywxk January 19, 2026 06:47

cfzjywxk approved these changes Jan 20, 2026

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ti-chi-bot bot added the lgtm label Jan 20, 2026

ti-chi-bot bot removed the needs-1-more-lgtm Indicates a PR needs 1 more LGTM. label Jan 20, 2026

ti-chi-bot bot merged commit 94acffc into tikv:master Jan 20, 2026
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ti-chi-bot bot added this to the Pool milestone Jan 20, 2026

you06 added the needs-cherry-pick-release-8.5 Should cherry pick this PR to release-8.5 branch. label Mar 4, 2026

ti-chi-bot pushed a commit to ti-chi-bot/tikv that referenced this pull request Mar 4, 2026

This is an automated cherry-pick of tikv#19282

7bf76c8

ref tikv#19087 Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>

ti-chi-bot mentioned this pull request Mar 4, 2026

txn: support shared lock for pessimistic / prewrite / commit schedulers (#19282) #19423

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you06 mentioned this pull request Mar 4, 2026

Support shared lock for foreign key #19087

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you06 commented Jan 13, 2026

What is changed and how it works?

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[LGTM Timeline notifier]

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