content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.beam.runners.dataflow.worker.util.common.worker;
  
  import java.io.Closeable;
  import java.util.List;
  import java.util.ListIterator;
  import org.apache.beam.runners.core.metrics.ExecutionStateTracker;
  import org.apache.beam.runners.dataflow.worker.counters.CounterSet;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Lists;
  import org.checkerframework.checker.nullness.qual.Nullable;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /** An executor for a map task, defined by a list of Operations. */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class MapTaskExecutor implements WorkExecutor {
    private static final Logger LOG = LoggerFactory.getLogger(MapTaskExecutor.class);
  
    /** The operations in the map task, in execution order. */
    public final List<Operation> operations;
  
    private final ExecutionStateTracker executionStateTracker;
  
    private final CounterSet counters;
  
    /**
     * Creates a new MapTaskExecutor.
     *
     * @param operations the operations of the map task, in order of execution
     * @param counters a set of system counters associated with operations, which may get extended
     *     during execution
     */
    public MapTaskExecutor(
        List<Operation> operations,
        CounterSet counters,
        ExecutionStateTracker executionStateTracker) {
      this.counters = counters;
      this.operations = operations;
      this.executionStateTracker = executionStateTracker;
    }
  
    @Override
    public CounterSet getOutputCounters() {
      return counters;
    }
  
    @Override
    public void execute() throws Exception {
      LOG.debug("Executing map task");
  
      try (Closeable stateCloser = executionStateTracker.activate()) {
        try {
          // Start operations, in reverse-execution-order, so that a
          // consumer is started before a producer might output to it.
          // Starting a root operation such as a ReadOperation does the work
          // of processing the input dataset.
          LOG.debug("Starting operations");
          ListIterator<Operation> iterator = operations.listIterator(operations.size());
          while (iterator.hasPrevious()) {
            if (Thread.currentThread().isInterrupted()) {
              throw new InterruptedException("Worker aborted");
            }
            Operation op = iterator.previous();
            op.start();
          }
  
          // Finish operations, in forward-execution-order, so that a
          // producer finishes outputting to its consumers before those
          // consumers are themselves finished.
          LOG.debug("Finishing operations");
          for (Operation op : operations) {
            if (Thread.currentThread().isInterrupted()) {
              throw new InterruptedException("Worker aborted");
            }
            op.finish();
          }
        } catch (Exception | Error exn) {
          LOG.debug("Aborting operations", exn);
          for (Operation op : operations) {
            try {
              op.abort();
            } catch (Exception | Error exn2) {
              exn.addSuppressed(exn2);
              if (exn2 instanceof InterruptedException) {
                Thread.currentThread().interrupt();
              }
            }
          }
          throw exn;
        }
      }
  
      LOG.debug("Map task execution complete");
  
      // TODO: support for success / failure ports?
    }
  
    @Override
    public NativeReader.Progress getWorkerProgress() throws Exception {
      return getReadOperation().getProgress();
    }
  
    @Override
    public NativeReader.@Nullable DynamicSplitResult requestCheckpoint() throws Exception {
      return getReadOperation().requestCheckpoint();
    }
  
    @Override
    public NativeReader.DynamicSplitResult requestDynamicSplit(
        NativeReader.DynamicSplitRequest splitRequest) throws Exception {
      return getReadOperation().requestDynamicSplit(splitRequest);
    }
  
    public ReadOperation getReadOperation() {
      if (operations == null || operations.isEmpty()) {
        throw new IllegalStateException("Map task has no operation.");
      }
  
      Operation readOperation = operations.get(0);
      if (!(readOperation instanceof ReadOperation)) {
        throw new IllegalStateException("First operation in the map task is not a ReadOperation.");
      }
  
      return (ReadOperation) readOperation;
    }
  
    public boolean supportsRestart() {
      for (Operation op : operations) {
        if (!op.supportsRestart()) {
          return false;
        }
      }
      return true;
    }
  
    @Override
    public void abort() {
      // Signal the read loop to abort on the next record and async abort any iterators.
      // TODO: Also interrupt the execution thread.
      for (Operation op : operations) {
        Preconditions.checkState(op instanceof ReadOperation || op instanceof ReceivingOperation);
        if (op instanceof ReadOperation) {
          ((ReadOperation) op).abortReadLoop();
        }
      }
    }
  
    @Override
    public List<Integer> reportProducedEmptyOutput() {
      List<Integer> emptyOutputSinkIndexes = Lists.newArrayList();
      for (Operation op : operations) {
        if (op instanceof WriteOperation) {
          WriteOperation write = (WriteOperation) op;
          int sinkIndex = write.reportSinkIndexIfEmptyOutput();
          if (sinkIndex != WriteOperation.INVALID_SINK_INDEX) {
            emptyOutputSinkIndexes.add(sinkIndex);
          }
        }
      }
      return emptyOutputSinkIndexes;
    }
  }
  