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;
  
  import java.util.List;
  import java.util.Set;
  import org.apache.beam.runners.core.DoFnRunner;
  import org.apache.beam.runners.core.KeyedWorkItem;
  import org.apache.beam.runners.core.KeyedWorkItems;
  import org.apache.beam.runners.core.StateNamespaces;
  import org.apache.beam.runners.core.StateTag;
  import org.apache.beam.runners.core.StateTags;
  import org.apache.beam.runners.core.StepContext;
  import org.apache.beam.runners.core.TimerInternals.TimerData;
  import org.apache.beam.runners.dataflow.worker.util.ValueInEmptyWindows;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.state.BagState;
  import org.apache.beam.sdk.state.TimeDomain;
  import org.apache.beam.sdk.state.ValueState;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Lists;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Sets;
  import org.joda.time.Instant;
  
  /**
   * A customized {@link DoFnRunner} that handles side inputs for a {@link KeyedWorkItem} input {@link
   * GroupAlsoByWindowFn}.
   *
   * <p>Input elements are postponed if the corresponding side inputs are not ready. It requires input
   * elements' windows are pre-expended.
   *
   * <p>{@link KeyedWorkItem KeyedWorkItems} are always in empty windows.
   *
   * @param <K> key type
   * @param <InputT> input value element type
   * @param <OutputT> output element type
   * @param <W> window type
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class StreamingKeyedWorkItemSideInputDoFnRunner<K, InputT, OutputT, W extends BoundedWindow>
      implements DoFnRunner<KeyedWorkItem<K, InputT>, OutputT> {
    private final DoFnRunner<KeyedWorkItem<K, InputT>, OutputT> simpleDoFnRunner;
    private final StreamingSideInputFetcher<InputT, W> sideInputFetcher;
    private final StateTag<ValueState<K>> keyAddr;
    private final StepContext stepContext;
    private final Set<K> storedKeys;
  
    public StreamingKeyedWorkItemSideInputDoFnRunner(
        DoFnRunner<KeyedWorkItem<K, InputT>, OutputT> simpleDoFnRunner,
        Coder<K> keyCoder,
        StreamingSideInputFetcher<InputT, W> sideInputFetcher,
        StepContext stepContext) {
      this.simpleDoFnRunner = simpleDoFnRunner;
      this.sideInputFetcher = sideInputFetcher;
      this.keyAddr = StateTags.makeSystemTagInternal(StateTags.value("key", keyCoder));
      this.stepContext = stepContext;
      this.storedKeys = Sets.newHashSet();
    }
  
    @Override
    public void startBundle() {
      simpleDoFnRunner.startBundle();
  
      // Find the set of ready windows.
      Set<W> readyWindows = sideInputFetcher.getReadyWindows();
  
      Iterable<BagState<WindowedValue<InputT>>> elementsBags =
          sideInputFetcher.prefetchElements(readyWindows);
      Iterable<BagState<TimerData>> timersBags = sideInputFetcher.prefetchTimers(readyWindows);
  
      K key = keyValue().read();
      Iterable<TimerData> timers = Iterables.concat(Iterables.transform(timersBags, BagState::read));
  
      Iterable<WindowedValue<InputT>> elements =
          Iterables.concat(Iterables.transform(elementsBags, BagState::read));
  
      if (!isEmpty(timers, elements)) {
        simpleDoFnRunner.processElement(
            new ValueInEmptyWindows<>(KeyedWorkItems.workItem(key, timers, elements)));
        for (BagState<WindowedValue<InputT>> bag : elementsBags) {
          bag.clear();
        }
        for (BagState<TimerData> bag : timersBags) {
          bag.clear();
        }
      }
      sideInputFetcher.releaseBlockedWindows(readyWindows);
    }
  
    @Override
    public void processElement(WindowedValue<KeyedWorkItem<K, InputT>> elem) {
      final K key = elem.getValue().key();
      if (!storedKeys.contains(key)) {
        keyValue().write(key);
        storedKeys.add(key);
      }
  
      List<WindowedValue<InputT>> readyInputs =
          Lists.newArrayList(
              Iterables.filter(
                  elem.getValue().elementsIterable(),
                  input -> !sideInputFetcher.storeIfBlocked(input)));
  
      List<TimerData> readyTimers =
          Lists.newArrayList(
              Iterables.filter(
                  elem.getValue().timersIterable(),
                  timer -> !sideInputFetcher.storeIfBlocked(timer)));
  
      if (!readyTimers.isEmpty() || !readyInputs.isEmpty()) {
        KeyedWorkItem<K, InputT> keyedWorkItem =
            KeyedWorkItems.workItem(elem.getValue().key(), readyTimers, readyInputs);
        simpleDoFnRunner.processElement(elem.withValue(keyedWorkItem));
      }
    }
  
    @Override
    public <KeyT> void onTimer(
        String timerId,
        String timerFamilyId,
        KeyT key,
        BoundedWindow window,
        Instant timestamp,
        Instant outputTimestamp,
        TimeDomain timeDomain) {
      throw new UnsupportedOperationException(
          "Attempt to deliver a timer to a DoFn, but timers are not supported in Dataflow.");
    }
  
    @Override
    public void finishBundle() {
      simpleDoFnRunner.finishBundle();
      sideInputFetcher.persist();
    }
  
    @Override
    public <KeyT> void onWindowExpiration(BoundedWindow window, Instant timestamp, KeyT key) {
      simpleDoFnRunner.onWindowExpiration(window, timestamp, key);
    }
  
    ValueState<K> keyValue() {
      return stepContext.stateInternals().state(StateNamespaces.global(), keyAddr);
    }
  
    private boolean isEmpty(Iterable<TimerData> timers, Iterable<WindowedValue<InputT>> elements) {
      return !timers.iterator().hasNext() && !elements.iterator().hasNext();
    }
  
    @Override
    public DoFn<KeyedWorkItem<K, InputT>, OutputT> getFn() {
      return simpleDoFnRunner.getFn();
    }
  }
  