txn: fix retried transactions' statements is not inclueded in TIDB_TRX (#28480)

[ti-srebot]

cherry-pick #28480 to release-5.2
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/28670

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/28670:release-5.2-07eb99dce5eb

---

What problem does this PR solve?

Problem Summary:

Currently the retried transactions' statements won't be inclueded in TIDB_TRX.

The reason is:

If we meet an retryable error here:

tidb/session/session.go

Line 701 in 091ae3b

err = s.doCommit(ctx)

note the origin datasource of TIDB_TRX for this transaction is resetted here inside doCommit:

tidb/session/session.go

Line 489 in 091ae3b

s.txn.changeToInvalid()

(and will be resetted again here if retry more than once):

tidb/session/session.go

Line 972 in 091ae3b

s.txn.changeToInvalid()

But during retrying, we use st.Exec(which may restart the transaction with session.Txn) instead of session.ExecStament, and st.Exec will not record statements.

tidb/session/session.go

Line 929 in 091ae3b

_, err = st.Exec(ctx)

What is changed and how it works?

What's Changed:
Collect them during retry.

Check List

Tests

• Unit test
• Integration test (automated-tests#851)
• Manual test
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory

Documentation

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

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• MyonKeminta
• jackysp

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[ti-srebot]

/run-all-tests

[ti-srebot]

@longfangsong you're already a collaborator in bot's repo.

[zhouqiang-cl]

/merge

[ti-chi-bot]

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

Commit hash: b79d4e7

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