com.google.cloud.dataflow.sdk.transforms.windowing.AfterAll Maven / Gradle / Ivy

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/*
 * Copyright (C) 2015 Google Inc.
 *
 * Licensed 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 com.google.cloud.dataflow.sdk.transforms.windowing;

import com.google.cloud.dataflow.sdk.annotations.Experimental;
import com.google.cloud.dataflow.sdk.transforms.windowing.Trigger.OnceTrigger;
import com.google.cloud.dataflow.sdk.util.ExecutableTrigger;
import com.google.common.base.Preconditions;

import org.joda.time.Instant;

import java.util.Arrays;
import java.util.List;

/**
 * Create a {@link Trigger} that fires and finishes once after all of its sub-triggers have fired.
 *
 * @param  {@link BoundedWindow} subclass used to represent the windows used by this
 *            {@code Trigger}
 */
@Experimental(Experimental.Kind.TRIGGER)
public class AfterAll extends OnceTrigger {

  private static final long serialVersionUID = 0L;

  private AfterAll(List> subTriggers) {
    super(subTriggers);
    Preconditions.checkArgument(subTriggers.size() > 1);
  }

  @SafeVarargs
  public static  OnceTrigger of(
      OnceTrigger... triggers) {
    return new AfterAll(Arrays.>asList(triggers));
  }

  private TriggerResult result(TriggerContext c) {
    // If all children have finished, then they must have each fired at least once.
    if (c.trigger().areAllSubtriggersFinished()) {
      return TriggerResult.FIRE_AND_FINISH;
    }

    return TriggerResult.CONTINUE;
  }

  @Override
  public TriggerResult onElement(OnElementContext c) throws Exception {
    for (ExecutableTrigger subTrigger : c.trigger().unfinishedSubTriggers()) {
      // Since subTriggers are all OnceTriggers, they must either CONTINUE or FIRE_AND_FINISH.
      // invokeElement will automatically mark the finish bit if they return FIRE_AND_FINISH.
      subTrigger.invokeElement(c);
    }

    return result(c);
  }

  @Override
  public MergeResult onMerge(OnMergeContext c) throws Exception {
    // CONTINUE if merging returns CONTINUE for at least one sub-trigger
    // FIRE_AND_FINISH if merging returns FIRE or FIRE_AND_FINISH for at least one sub-trigger
    //   *and* FIRE, FIRE_AND_FINISH, or FINISH for all other sub-triggers.
    // FINISH if merging returns FINISH for all sub-triggers.
    boolean fired = false;
    for (ExecutableTrigger subTrigger : c.trigger().subTriggers()) {
      MergeResult result = subTrigger.invokeMerge(c);
      if (MergeResult.CONTINUE.equals(result)) {
        return MergeResult.CONTINUE;
      }
      fired |= result.isFire();
    }

    return fired ? MergeResult.FIRE_AND_FINISH : MergeResult.ALREADY_FINISHED;
  }

  @Override
  public TriggerResult onTimer(OnTimerContext c) throws Exception {
    for (ExecutableTrigger subTrigger : c.trigger().unfinishedSubTriggers()) {
      // Since subTriggers are all OnceTriggers, they must either CONTINUE or FIRE_AND_FINISH.
      // invokeTimer will automatically mark the finish bit if they return FIRE_AND_FINISH.
      subTrigger.invokeTimer(c);
    }

    return result(c);
  }

  @Override
  public Instant getWatermarkThatGuaranteesFiring(W window) {
    // This trigger will fire after the latest of its sub-triggers.
    Instant deadline = BoundedWindow.TIMESTAMP_MIN_VALUE;
    for (Trigger subTrigger : subTriggers) {
      Instant subDeadline = subTrigger.getWatermarkThatGuaranteesFiring(window);
      if (deadline.isBefore(subDeadline)) {
        deadline = subDeadline;
      }
    }
    return deadline;
  }

  @Override
  public OnceTrigger getContinuationTrigger(List> continuationTriggers) {
    return new AfterAll(continuationTriggers);
  }
}