[ISSUE #10748] Fix unsupported ProxyChannel command completion

[ai-yang]

Which Issue(s) This PR Fixes

• Fixes [Bug] ProxyChannel leaves unsupported RemotingCommand writes permanently pending #10748

Brief Description

ProxyChannel.writeAndFlush() created an incomplete processFuture before dispatching a RemotingCommand, but the default switch branch only broke out of the switch. No producer remained that could complete the future, so the returned channel future stayed pending forever.

This change:

• completes the existing processing future exceptionally for unsupported remoting command codes;
• includes the unsupported request code in the failure for diagnosis;
• keeps relay services untouched for commands that have no supported dispatch path;
• reports that the command was not delivered instead of returning success or waiting for a response that cannot arrive.

How Did You Test This Change?

• Unmodified develop: the deterministic strengthened regression failed in 5/5 isolated JDK 8 Maven processes.
• Fixed regression: 20 isolated Maven/JVM processes at 1/1 each (20/20 total).
• Complete proxy -am reactor: all 11 modules passed with 0 failures and 0 errors.
• Project Checkstyle: 0 violations.
• SpotBugs: 0 bug instances and 0 errors.
• Maven validate: passed.
• git diff --check: passed.

Compatibility and Failure Semantics

Supported RemotingCommand branches and non-RemotingCommand messages are unchanged. Only the unsupported request-code branch changes: instead of leaving the returned ChannelFuture pending forever, it now completes exceptionally and does not invoke a relay service, allowing callers to observe that the command was not delivered.

[RockteMQ-AI]

Review by github-manager-bot

Summary

Fixes a resource leak where unsupported remoting commands in ProxyChannel.writeAndFlush would leave the processFuture hanging indefinitely by completing it with UnsupportedOperationException in the default switch case.

Findings

• [Info] ProxyChannel.java:114 — Adding processFuture.completeExceptionally() in the default case is the correct fix. Previously, callers waiting on the future for an unsupported command code would block forever, potentially leaking threads and memory.
• [Info] The exception message includes the unsupported command code, which aids debugging.
• [Info] ProxyChannelTest.java — Test verifies that the future completes with failure, the cause is UnsupportedOperationException, and the message contains the command code. Also verifies no interaction with the relay service for unsupported commands.

Suggestions

• None. Simple, correct fix with good test coverage.

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Automated review by github-manager-bot

[RockteMQ-AI]

Summary

Defensive fix with proper validation and test coverage. LGTM.

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Automated review by github-manager-bot

[ai-yang]

@lizhimins @lollipopjin, could you please take a human review when convenient? This is a focused ProxyChannel completion fix: unsupported remoting command codes now fail the returned future instead of leaving it pending, while supported branches remain unchanged. The complete 11-module reactor, Checkstyle, and SpotBugs pass. The remaining GitHub Actions runs are currently awaiting maintainer approval.