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.sdk.transforms.windowing;
  
  import java.util.Arrays;
  import java.util.List;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
  import org.joda.time.Instant;
  
  /**
   * A {@link Trigger} that executes according to its main trigger until its "finally" trigger fires.
   *
   * <p>Uniquely among triggers, the "finally" trigger's predicate is applied to all input seen so
   * far, not input since the last firing.
   */
  public class OrFinallyTrigger extends Trigger {
  
    private static final int ACTUAL = 0;
    private static final int UNTIL = 1;
  
    @VisibleForTesting
    OrFinallyTrigger(Trigger actual, Trigger.OnceTrigger until) {
      super(Arrays.asList(actual, until));
    }
  
    /**
     * The main trigger, which will continue firing until the "until" trigger fires. See {@link
     * #getUntilTrigger()}
     */
    public Trigger getMainTrigger() {
      return subTriggers().get(ACTUAL);
    }
  
    /** The trigger that signals termination of this trigger. */
    public OnceTrigger getUntilTrigger() {
      return (OnceTrigger) subTriggers().get(UNTIL);
    }
  
    @Override
    public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) {
      // This trigger fires once either the trigger or the until trigger fires.
      Instant actualDeadline = subTriggers.get(ACTUAL).getWatermarkThatGuaranteesFiring(window);
      Instant untilDeadline = subTriggers.get(UNTIL).getWatermarkThatGuaranteesFiring(window);
      return actualDeadline.isBefore(untilDeadline) ? actualDeadline : untilDeadline;
    }
  
    @Override
    public boolean mayFinish() {
      return subTriggers.get(ACTUAL).mayFinish() || subTriggers.get(UNTIL).mayFinish();
    }
  
    @Override
    protected Trigger getContinuationTrigger(List<Trigger> continuationTriggers) {
      // Use OrFinallyTrigger instead of AfterFirst because the continuation of ACTUAL
      // may not be a OnceTrigger.
      return Repeatedly.forever(
          new OrFinallyTrigger(
              continuationTriggers.get(ACTUAL),
              (Trigger.OnceTrigger) continuationTriggers.get(UNTIL)));
    }
  
    @Override
    public String toString() {
      return String.format("%s.orFinally(%s)", subTriggers.get(ACTUAL), subTriggers.get(UNTIL));
    }
  }
  