[songgaoye]

What problem does this PR solve?

Issue Number: resolve

Problem Summary:

RedisClusterChannel makes avoidable copies while parsing commands and
aggregating MGET replies:

• Parsed commands are copied into the command list after construction.
• Each sub-reply is shared into an intermediate vector and then shared again
  into the final Redis reply, causing redundant IOBuf block-reference
  operations.

What is changed and the side effects?

Changed:

• Move completed ParsedCommand objects into the parsed command list.
• Move each MGET sub-reply into the intermediate reply vector.
• Move intermediate replies into the final aggregated reply.

Side effects:

• Performance effects:

  Avoids copying command argument vectors and eliminates two IOBuf
  block-reference copy/release cycles per aggregated MGET element.

• Breaking backward compatibility:

  None.

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Check List:

• Please make sure your changes are compilable.
• When providing us with a new feature, it is best to add related tests.
• Please follow Contributor Covenant Code of Conduct.

[Copilot]

🟡 Changes recommended

The change has an active critical correctness issue that can truncate sufficiently large GET replies, along with an additional efficiency issue in the same construction path.

2 open issues

• Movable conversion truncates values spanning more than two blocks · New
• push_back copies the temporary IOBuf instead of constructing in place · New

What changed in this PR

This PR reduces redundant copying in RedisClusterChannel while parsing commands and aggregating Redis MGET replies.

Changes:

• Moves completed ParsedCommand objects into the command list.
• Moves MGET sub-replies into the intermediate reply collection.
• Moves intermediate replies into the final encoded response.

File	Description	Review findings
src/​brpc/​redis_cluster.cpp	Applies move-based command parsing and MGET reply aggregation.	Critical (1 vote): The push_back conversion from IOBuf::Movable can truncate sufficiently large GET replies and leave the big-view allocation unmanaged; use a transfer operation that preserves big views. Nit (2 votes): Use emplace_back to avoid materializing and copying a temporary IOBuf.

_{Review effort: Lite}