Fix pipe consensus compatibility during rolling upgrade

[Pengzna]

Summary

• add compatibility aliases for legacy pipe-consensus builtin processor and async connector/sink names
• normalize persisted IoTConsensusV2 protocol class names on DataNode and ConfigNode restart and rewrite system properties for compatibility
• add DataNode plugin agent coverage for the legacy pipe-consensus plugin names

[Copilot]

Pull request overview

Adds rolling-upgrade compatibility for legacy pipe-consensus plugin/protocol names by introducing aliases and normalizing persisted consensus protocol class names so mixed-version clusters can restart cleanly.

Changes:

• Add builtin pipe plugin aliases for legacy pipe-consensus-* processor/connector/sink names.
• Normalize persisted IoTConsensusV2-related consensus protocol class names on DataNode/ConfigNode restart and rewrite system properties when needed.
• Extend DataNode plugin agent test coverage for legacy pipe-consensus names (processor/connector).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/pipe/agent/plugin/builtin/BuiltinPipePlugin.java	Adds legacy pipe-consensus-* builtin plugin name aliases mapping to IoTConsensusV2 implementations.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/agent/plugin/dataregion/PipeDataRegionProcessorConstructor.java	Registers the legacy processor alias so DataNode can instantiate the correct processor.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/agent/plugin/dataregion/PipeDataRegionSinkConstructor.java	Registers the legacy async connector/sink aliases so DataNode can instantiate the correct sink.
iotdb-core/datanode/src/test/java/org/apache/iotdb/db/pipe/agent/plugin/PipeDataNodePluginAgentTest.java	Adds assertions to validate legacy processor/connector alias resolution in the DataNode plugin agent.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/conf/IoTDBStartCheck.java	Normalizes persisted DataNode consensus protocol class names and rewrites system properties for compatibility.
iotdb-core/consensus/src/main/java/org/apache/iotdb/consensus/ConsensusFactory.java	Adds normalization helper and applies it before consensus implementation construction.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/conf/SystemPropertiesUtils.java	Normalizes persisted ConfigNode consensus protocol class names and rewrites system properties for compatibility.

Comments suppressed due to low confidence (1)

iotdb-core/consensus/src/main/java/org/apache/iotdb/consensus/ConsensusFactory.java:77

• getConsensusImpl now normalizes className, but if className is null/blank the subsequent Class.forName(className) will throw a NullPointerException, which is not caught here (only checked exceptions are caught). Add an explicit null/blank guard after normalization that logs a clear error and returns Optional.empty() to prevent startup crashes with confusing stack traces.

  public static Optional<IConsensus> getConsensusImpl(
      String className, ConsensusConfig config, IStateMachine.Registry registry) {
    try {
      className = normalizeConsensusProtocolClass(className);
      // special judge for IoTConsensusV2
      if (IOT_CONSENSUS_V2.equals(className)) {
        className = REAL_IOT_CONSENSUS_V2;
        // initialize iotConsensusV2's thrift component
        IoTV2GlobalComponentContainer.build();
        // initialize iotConsensusV2's metric component
        IoTConsensusV2SyncLagManager.build();
      }
      Class<?> executor = Class.forName(className);
      Constructor<?> executorConstructor =

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[Copilot]

In checkSystemProperties, persisted*ConsensusProtocolClass is read with a null default. If the key is missing (e.g., upgrading from an older/partial system properties file), normalizeConsensusProtocolClass(null) returns null, and the code will end up calling conf.set*ConsensusProtocolClass(null), which can later lead to a NullPointerException when constructing the consensus implementation. Consider falling back to the current conf value (or a known default) when the persisted value is null/blank, and avoid ever writing/setting a null consensus protocol class.

[Copilot]

The new compatibility alias PIPE_CONSENSUS_ASYNC_SINK is added in the constructors, but the test only verifies the legacy processor and connector aliases. Consider adding an assertion that reflectSink also resolves when the sink key is set to BuiltinPipePlugin.PIPE_CONSENSUS_ASYNC_SINK.getPipePluginName() (i.e., cover the sink alias path, not just connector).

Suggested change

	.getClass());
	.getClass());
	Assert.assertEquals(
	IoTConsensusV2AsyncSink.class,
	agent
	.dataRegion()
	.reflectSink(
	new PipeParameters(
	new HashMap<String, String>() {
	{
	put(
	PipeSinkConstant.SINK_KEY,
	BuiltinPipePlugin.PIPE_CONSENSUS_ASYNC_SINK.getPipePluginName());
	}
	}))
	.getClass());