Pipe: Fix connection leak caused by clients not closed after task dropped (2 situations)

[SteveYurongSu]

This pull request introduces several changes across multiple files to improve connection management, enhance error handling, and ensure proper resource cleanup. The most notable updates include replacing direct clientManager calls with a getClientManager() method for safer access, adding checks to prevent operations after closure, and improving logging for debugging purposes.

Connection Management Improvements:

• iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/pipe/connector/protocol/IoTDBSslSyncConnector.java: Replaced direct clientManager access with a getClientManager() method that throws an exception if the client manager is closed, ensuring safer access.
• iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/pipe/connector/protocol/IoTDBSslSyncConnector.java: Updated methods like handshake and sendHandshakeReq to use getClientManager() instead of directly accessing clientManager. [1] [2]

Resource Cleanup Enhancements:

• iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/client/IoTDBDataNodeAsyncClientManager.java: Added logic to close clients and invalidate resources in cases where the manager is closed, preventing connection leaks. [1] [2]
• iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/client/ClientManager.java: Enhanced the returnClient method to handle cases where the node is null, invalidating resources to prevent leaks.

Error Handling Improvements:

• iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/protocol/thrift/async/handler/PipeTransferTsFileHandler.java: Improved error handling and resource cleanup when the connector is closed, with detailed logging for debugging.
• iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/client/async/AsyncPipeDataTransferServiceClient.java: Made the close method public for better resource management.

Operational Safety Enhancements:

• iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/agent/task/subtask/connector/PipeConnectorSubtask.java: Added a check to prevent heartbeat or transfer operations after the connector is closed.
• iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/protocol/thrift/async/IoTDBDataRegionAsyncConnector.java: Updated the heartbeat method to ensure it does not execute if the connector is closed.

These changes collectively enhance the robustness of the system by ensuring safer client management, preventing resource leaks, and improving error handling and operational safety.

[sonarqubecloud]

Quality Gate failed

Failed conditions
B Reliability Rating on New Code (required ≥ A)

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[codecov]

Codecov Report

Attention: Patch coverage is 8.69565% with 42 lines in your changes missing coverage. Please review.

Project coverage is 39.07%. Comparing base (966cfc7) to head (f934d31).
Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
...hrift/async/handler/PipeTransferTsFileHandler.java	0.00%	12 Missing ⚠️
...nector/client/IoTDBDataNodeAsyncClientManager.java	0.00%	10 Missing ⚠️
...pipe/connector/protocol/IoTDBSslSyncConnector.java	0.00%	6 Missing ⚠️
...org/apache/iotdb/commons/client/ClientManager.java	37.50%	5 Missing ⚠️
...connector/protocol/IoTDBConfigRegionConnector.java	0.00%	4 Missing ⚠️
...ol/thrift/async/IoTDBDataRegionAsyncConnector.java	0.00%	2 Missing ⚠️
...ft/async/handler/PipeTransferTrackableHandler.java	0.00%	2 Missing ⚠️
...t/task/subtask/connector/PipeConnectorSubtask.java	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #15910      +/-   ##
============================================
- Coverage     39.09%   39.07%   -0.02%     
  Complexity      198      198              
============================================
  Files          4847     4847              
  Lines        315799   315914     +115     
  Branches      39658    39672      +14     
============================================
- Hits         123448   123434      -14     
- Misses       192351   192480     +129     

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