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.List;
  import java.util.Objects;
  import org.apache.beam.sdk.transforms.windowing.Trigger.OnceTrigger;
  import org.checkerframework.checker.nullness.qual.Nullable;
  import org.joda.time.Instant;
  
  /**
   * A {@link Trigger} that fires at some point after a specified number of input elements have
   * arrived.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class AfterPane extends OnceTrigger {
  
    private final int countElems;
  
    private AfterPane(int countElems) {
      super(null);
      this.countElems = countElems;
    }
  
    /** The number of elements after which this trigger may fire. */
    public int getElementCount() {
      return countElems;
    }
  
    /** Creates a trigger that fires when the pane contains at least {@code countElems} elements. */
    public static AfterPane elementCountAtLeast(int countElems) {
      return new AfterPane(countElems);
    }
  
    @Override
    public boolean isCompatible(Trigger other) {
      return this.equals(other);
    }
  
    @Override
    public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) {
      return BoundedWindow.TIMESTAMP_MAX_VALUE;
    }
  
    @Override
    protected OnceTrigger getContinuationTrigger(List<Trigger> continuationTriggers) {
      return AfterPane.elementCountAtLeast(1);
    }
  
    @Override
    public String toString() {
      return "AfterPane.elementCountAtLeast(" + countElems + ")";
    }
  
    @Override
    public boolean equals(@Nullable Object obj) {
      if (this == obj) {
        return true;
      }
      if (!(obj instanceof AfterPane)) {
        return false;
      }
      AfterPane that = (AfterPane) obj;
      return this.countElems == that.countElems;
    }
  
    @Override
    public int hashCode() {
      return Objects.hash(countElems);
    }
  }
  