[ISSUE #10968] Copy transaction message properties directly instead of encode/decode roundtrip

[wang-jiahua]

Which Issue(s) This PR Fixes

Fixes #10968

Brief Description

EndTransactionProcessor#endMessageTransaction deep-copied the prepare message's properties by encoding them to a String and immediately decoding that String back to a map:

MessageAccessor.setProperties(msgInner,
    MessageDecoder.string2messageProperties(MessageDecoder.messageProperties2String(msgExt.getProperties())));

That is a full map traversal + StringBuilder + String, then a second traversal + per-entry substring allocations — on every transaction commit/rollback — just to copy a map. This PR replaces the round-trip with MessageAccessor.deepCopyProperties(...). The real encode after clearProperty (which produces the wire-format propertiesString) is untouched, so the stored message is byte-identical.

Behavior parity note: the old round-trip silently dropped entries with null/empty values, but at this call site msgExt is decoded from the store — the properties parser never yields null/empty values and putUserProperty rejects blank values, so that path is unreachable here.

How Did You Test This Change?

• EndTransactionProcessorTest passes (7/7).
• A/B benchmark on a 4-node cluster (8C32G, ESSD): benchmark.TransactionProducer, 32 threads, 1 KiB body, all-commit; per arm clean store + broker restart + page cache drop; 25 s warmup + 60 s collect; 3 interleaved trials:

trial	arm	TPS	young GC	GC / million msgs	send failed
1	base	64,927	25	6.42	0
1	patch	66,767	24	5.99	0
2	base	66,078	26	6.56	0
2	patch	64,868	24	6.17	0
3	base	66,781	25	6.24	0
3	patch	65,184	24	6.14	0

Broker young GC per million messages: median 6.42 -> 6.14 (-4.4%), patch below base in all three trials; TPS flat; zero send failures.

[Copilot]

Pull request overview

This PR optimizes transaction end-message handling in the broker by replacing a properties encode/decode round-trip (used solely for deep-copying) with a direct map copy via MessageAccessor.deepCopyProperties(...), reducing unnecessary allocations during transaction commit/rollback.

Changes:

• Replace MessageDecoder.messageProperties2String(...) + MessageDecoder.string2messageProperties(...) copy round-trip with MessageAccessor.deepCopyProperties(...) in EndTransactionProcessor#endMessageTransaction.
• Preserve the existing final propertiesString encode after clearProperty, keeping persisted wire-format behavior unchanged.

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[RockteMQ-AI]

LGTM. Replacing the encode/decode roundtrip with MessageAccessor.deepCopyProperties(...) is a clean improvement. The method already exists and is used in TimerMessageStore and TimerMessageRocksDBStore, so this is consistent with established patterns. The behavior parity analysis in the PR description is thorough — the null/empty value path is indeed unreachable at this call site since msgExt properties come from the store decoder.

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Automated review by github-manager-bot

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 48.50%. Comparing base (e348efa) to head (8c664ed).

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #10970      +/-   ##
=============================================
- Coverage      48.56%   48.50%   -0.07%     
+ Complexity     13672    13652      -20     
=============================================
  Files           1381     1381              
  Lines         101475   101475              
  Branches       13190    13190              
=============================================
- Hits           49286    49216      -70     
- Misses         46185    46243      +58     
- Partials        6004     6016      +12     

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