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.direct;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkNotNull;
  
  import org.apache.beam.runners.direct.DirectRunner.Enforcement;
  import org.apache.beam.runners.local.StructuralKey;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.coders.CoderException;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.util.IllegalMutationException;
  import org.apache.beam.sdk.util.MutationDetector;
  import org.apache.beam.sdk.util.MutationDetectors;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.HashMultimap;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.SetMultimap;
  import org.joda.time.Instant;
  
  /**
   * A {@link BundleFactory} that ensures that elements added to it are not mutated after being
   * output. Immutability checks are enforced at the time {@link UncommittedBundle#commit(Instant)} is
   * called, checking the value at that time against the value at the time the element was added. All
   * elements added to the bundle will be encoded by the {@link Coder} of the underlying {@link
   * PCollection}.
   *
   * <p>This catches errors during the execution of a {@link DoFn} caused by modifying an element
   * after it is added to an output {@link PCollection}.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class ImmutabilityCheckingBundleFactory implements BundleFactory {
    /**
     * Create a new {@link ImmutabilityCheckingBundleFactory} that uses the underlying {@link
     * BundleFactory} to create the output bundle.
     */
    public static ImmutabilityCheckingBundleFactory create(
        BundleFactory underlying, DirectGraph graph) {
      return new ImmutabilityCheckingBundleFactory(underlying, graph);
    }
  
    private final BundleFactory underlying;
    private final DirectGraph graph;
  
    private ImmutabilityCheckingBundleFactory(BundleFactory underlying, DirectGraph graph) {
      this.underlying = checkNotNull(underlying);
      this.graph = graph;
    }
  
    /**
     * {@inheritDoc}.
     *
     * @return a root bundle created by the underlying {@link PCollection}. Root bundles belong to the
     *     runner, which is required to use the contents in a way that is mutation-safe.
     */
    @Override
    public <T> UncommittedBundle<T> createRootBundle() {
      return underlying.createRootBundle();
    }
  
    @Override
    public <T> UncommittedBundle<T> createBundle(PCollection<T> output) {
      if (Enforcement.IMMUTABILITY.appliesTo(output, graph)) {
        return new ImmutabilityEnforcingBundle<>(underlying.createBundle(output));
      }
      return underlying.createBundle(output);
    }
  
    @Override
    public <K, T> UncommittedBundle<T> createKeyedBundle(
        StructuralKey<K> key, PCollection<T> output) {
      if (Enforcement.IMMUTABILITY.appliesTo(output, graph)) {
        return new ImmutabilityEnforcingBundle<>(underlying.createKeyedBundle(key, output));
      }
      return underlying.createKeyedBundle(key, output);
    }
  
    private class ImmutabilityEnforcingBundle<T> implements UncommittedBundle<T> {
      private final UncommittedBundle<T> underlying;
      private final SetMultimap<WindowedValue<T>, MutationDetector> mutationDetectors;
      private Coder<T> coder;
  
      public ImmutabilityEnforcingBundle(UncommittedBundle<T> underlying) {
        this.underlying = underlying;
        mutationDetectors = HashMultimap.create();
        coder = getPCollection().getCoder();
      }
  
      @Override
      public PCollection<T> getPCollection() {
        return underlying.getPCollection();
      }
  
      @Override
      public UncommittedBundle<T> add(WindowedValue<T> element) {
        try {
          mutationDetectors.put(
              element, MutationDetectors.forValueWithCoder(element.getValue(), coder));
        } catch (CoderException e) {
          throw new RuntimeException(e);
        }
        underlying.add(element);
        return this;
      }
  
      @Override
      public CommittedBundle<T> commit(Instant synchronizedProcessingTime) {
        for (MutationDetector detector : mutationDetectors.values()) {
          try {
            detector.verifyUnmodified();
          } catch (IllegalMutationException exn) {
            throw new IllegalMutationException(
                String.format(
                    "PTransform %s mutated value %s after it was output (new value was %s)."
                        + " Values must not be mutated in any way after being output.",
                    graph.getProducer(underlying.getPCollection()).getFullName(),
                    exn.getSavedValue(),
                    exn.getNewValue()),
                exn.getSavedValue(),
                exn.getNewValue(),
                exn);
          }
        }
        return underlying.commit(synchronizedProcessingTime);
      }
    }
  }
  