Pipe: discard batched events before restarting pipes

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/payload/evolvable/batch/PipeTabletEventBatch.java

@@ -20,6 +20,7 @@
 package org.apache.iotdb.db.pipe.connector.payload.evolvable.batch;
 
 import org.apache.iotdb.commons.pipe.event.EnrichedEvent;
+import org.apache.iotdb.db.pipe.connector.protocol.thrift.async.IoTDBDataRegionAsyncConnector;
 import org.apache.iotdb.db.storageengine.dataregion.wal.exception.WALPipeException;
 import org.apache.iotdb.pipe.api.event.Event;
 import org.apache.iotdb.pipe.api.event.dml.insertion.TabletInsertionEvent;
@@ -115,7 +116,23 @@ public synchronized void close() {
     events.clear();
   }
 
-  public void decreaseEventsReferenceCount(final String holderMessage, final boolean shouldReport) {
+  /**
+   * Discard all events of the given pipe. This method only clears the reference count of the events
+   * and discard them, but do not modify other objects (such as buffers) for simplicity.
+   */
+  public synchronized void discardEventsOfPipe(final String pipeNameToDrop) {
+    events.removeIf(
+        event -> {
+          if (pipeNameToDrop.equals(event.getPipeName())) {
+            event.clearReferenceCount(IoTDBDataRegionAsyncConnector.class.getName());
+            return true;
+          }
+          return false;
+        });
+  }
+
+  public synchronized void decreaseEventsReferenceCount(
+      final String holderMessage, final boolean shouldReport) {
     events.forEach(event -> event.decreaseReferenceCount(holderMessage, shouldReport));
   }
 

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/payload/evolvable/batch/PipeTransferBatchReqBuilder.java

@@ -184,6 +184,11 @@ public boolean isEmpty() {
         && endPointToBatch.values().stream().allMatch(PipeTabletEventPlainBatch::isEmpty);
   }
 
+  public synchronized void discardEventsOfPipe(final String pipeNameToDrop) {
+    defaultBatch.discardEventsOfPipe(pipeNameToDrop);
+    endPointToBatch.values().forEach(batch -> batch.discardEventsOfPipe(pipeNameToDrop));
+  }
+
   @Override
   public synchronized void close() {
     defaultBatch.close();

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/protocol/thrift/async/IoTDBDataRegionAsyncConnector.java

@@ -515,11 +515,9 @@ public synchronized void clearRetryEventsReferenceCount() {
 
   //////////////////////////// Operations for close ////////////////////////////
 
-  /**
-   * When a pipe is dropped, the connector maybe reused and will not be closed. So we just discard
-   * its queued events in the output pipe connector.
-   */
+  @Override
   public synchronized void discardEventsOfPipe(final String pipeNameToDrop) {
+    tabletBatchBuilder.discardEventsOfPipe(pipeNameToDrop);
     retryEventQueue.removeIf(
         event -> {
           if (event instanceof EnrichedEvent

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/connector/protocol/thrift/sync/IoTDBDataRegionSyncConnector.java

@@ -492,6 +492,11 @@ private void doTransfer(
     LOGGER.info("Successfully transferred file {}.", tsFile);
   }
 
+  @Override
+  public synchronized void discardEventsOfPipe(final String pipeNameToDrop) {
+    tabletBatchBuilder.discardEventsOfPipe(pipeNameToDrop);
+  }
+
   @Override
   public void close() {
     if (tabletBatchBuilder != null) {

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/task/subtask/connector/PipeConnectorSubtask.java

@@ -21,6 +21,7 @@
 
 import org.apache.iotdb.commons.exception.pipe.PipeRuntimeException;
 import org.apache.iotdb.commons.pipe.config.PipeConfig;
+import org.apache.iotdb.commons.pipe.connector.protocol.IoTDBConnector;
 import org.apache.iotdb.commons.pipe.event.EnrichedEvent;
 import org.apache.iotdb.commons.pipe.task.connection.UnboundedBlockingPendingQueue;
 import org.apache.iotdb.commons.pipe.task.subtask.PipeAbstractConnectorSubtask;
@@ -268,8 +269,8 @@ public void discardEventsOfPipe(final String pipeNameToDrop) {
       }
     }
 
-    if (outputPipeConnector instanceof IoTDBDataRegionAsyncConnector) {
-      ((IoTDBDataRegionAsyncConnector) outputPipeConnector).discardEventsOfPipe(pipeNameToDrop);
+    if (outputPipeConnector instanceof IoTDBConnector) {
+      ((IoTDBConnector) outputPipeConnector).discardEventsOfPipe(pipeNameToDrop);
     }
   }
 

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/task/subtask/connector/PipeConnectorSubtaskLifeCycle.java

@@ -89,7 +89,7 @@ public synchronized void register() {
    *     the {@link PipeConnectorSubtask} should never be used again
    * @throws IllegalStateException if {@link PipeConnectorSubtaskLifeCycle#registeredTaskCount} <= 0
    */
-  public synchronized boolean deregister(String pipeNameToDeregister) {
+  public synchronized boolean deregister(final String pipeNameToDeregister) {
     if (registeredTaskCount <= 0) {
       throw new IllegalStateException("registeredTaskCount <= 0");
     }

iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/pipe/connector/protocol/IoTDBConnector.java

@@ -452,6 +452,14 @@ public void rateLimitIfNeeded(
     GLOBAL_RATE_LIMITER.acquire(bytesLength);
   }
 
+  /**
+   * When a pipe is dropped, the connector maybe reused and will not be closed. We need to discard
+   * its batched or queued events in the output pipe connector.
+   */
+  public synchronized void discardEventsOfPipe(final String pipeName) {
+    // Do nothing by default
+  }
+
   public PipeReceiverStatusHandler statusHandler() {
     return receiverStatusHandler;
   }