public double getTotalCompressedSize() {
    return outputPipeConnector instanceof IoTDBConnector
        ? ((IoTDBConnector) outputPipeConnector).getTotalCompressedSize()
        : 0;
  }
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.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/agent/task/subtask/connector/PipeConnectorSubtask.java