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;
  
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.beam.runners.core.InMemoryTimerInternals;
  import org.apache.beam.runners.core.NullSideInputReader;
  import org.apache.beam.runners.core.ReduceFnRunner;
  import org.apache.beam.runners.core.SideInputReader;
  import org.apache.beam.runners.core.StateInternals;
  import org.apache.beam.runners.core.StateInternalsFactory;
  import org.apache.beam.runners.core.StepContext;
  import org.apache.beam.runners.core.SystemReduceFn;
  import org.apache.beam.runners.core.TimerInternals.TimerData;
  import org.apache.beam.runners.core.triggers.ExecutableTriggerStateMachine;
  import org.apache.beam.runners.core.triggers.TriggerStateMachines;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.util.WindowedValueReceiver;
  import org.apache.beam.sdk.util.construction.TriggerTranslation;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.sdk.values.WindowingStrategy;
  import org.joda.time.Instant;
  
  /**
   * The default batch {@link BatchGroupAlsoByWindowFn} implementation, if no specialized "fast path"
   * implementation is applicable.
   */
  public class BatchGroupAlsoByWindowViaOutputBufferFn<K, InputT, OutputT, W extends BoundedWindow>
      extends BatchGroupAlsoByWindowFn<K, InputT, OutputT> {
  
    private final WindowingStrategy<?, W> strategy;
    private final StateInternalsFactory<K> stateInternalsFactory;
    private SystemReduceFn<K, InputT, ?, OutputT, W> reduceFn;
  
    public BatchGroupAlsoByWindowViaOutputBufferFn(
        WindowingStrategy<?, W> windowingStrategy,
        StateInternalsFactory<K> stateInternalsFactory,
        SystemReduceFn<K, InputT, ?, OutputT, W> reduceFn) {
      this.strategy = windowingStrategy;
      this.reduceFn = reduceFn;
      this.stateInternalsFactory = stateInternalsFactory;
    }
  
    @Override
    public void processElement(
        KV<K, Iterable<WindowedValue<InputT>>> element,
        PipelineOptions options,
        StepContext stepContext,
        SideInputReader sideInputReader,
        WindowedValueReceiver<KV<K, OutputT>> output)
        throws Exception {
      K key = element.getKey();
      // Used with Batch, we know that all the data is available for this key. We can't use the
      // timer manager from the context because it doesn't exist. So we create one and emulate the
      // watermark, knowing that we have all data and it is in timestamp order.
      InMemoryTimerInternals timerInternals = new InMemoryTimerInternals();
      timerInternals.advanceProcessingTime(Instant.now());
      timerInternals.advanceSynchronizedProcessingTime(Instant.now());
      StateInternals stateInternals = stateInternalsFactory.stateInternalsForKey(key);
  
      ReduceFnRunner<K, InputT, OutputT, W> reduceFnRunner =
          new ReduceFnRunner<>(
              key,
              strategy,
              ExecutableTriggerStateMachine.create(
                  TriggerStateMachines.stateMachineForTrigger(
                      TriggerTranslation.toProto(strategy.getTrigger()))),
              stateInternals,
              timerInternals,
              output,
              NullSideInputReader.empty(),
              reduceFn,
              options);
  
      // Process the elements.
      reduceFnRunner.processElements(element.getValue());
  
      // Finish any pending windows by advancing the input watermark to infinity.
      timerInternals.advanceInputWatermark(BoundedWindow.TIMESTAMP_MAX_VALUE);
  
      // Finally, advance the processing time to infinity to fire any timers.
      timerInternals.advanceProcessingTime(BoundedWindow.TIMESTAMP_MAX_VALUE);
      timerInternals.advanceSynchronizedProcessingTime(BoundedWindow.TIMESTAMP_MAX_VALUE);
  
      fireEligibleTimers(timerInternals, reduceFnRunner);
  
      reduceFnRunner.persist();
    }
  
    private void fireEligibleTimers(
        InMemoryTimerInternals timerInternals, ReduceFnRunner<K, InputT, OutputT, W> reduceFnRunner)
        throws Exception {
      List<TimerData> timers = new ArrayList<>();
      while (true) {
        TimerData timer;
        while ((timer = timerInternals.removeNextEventTimer()) != null) {
          timers.add(timer);
        }
        while ((timer = timerInternals.removeNextProcessingTimer()) != null) {
          timers.add(timer);
        }
        while ((timer = timerInternals.removeNextSynchronizedProcessingTimer()) != null) {
          timers.add(timer);
        }
        if (timers.isEmpty()) {
          break;
        }
        reduceFnRunner.onTimers(timers);
        timers.clear();
      }
    }
  }
  