| /* |
| * 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 org.apache.beam.sdk.annotations.Experimental; |
| import org.joda.time.Instant; |
| |
| /** |
| * A trigger that is equivalent to {@code Repeatedly.forever(AfterWatermark.pastEndOfWindow())}. See |
| * {@link Repeatedly#forever} and {@link AfterWatermark#pastEndOfWindow} for more details. |
| * |
| * <p>This is a distinguished class to make it easy for runners to optimize for this common case. |
| */ |
| @Experimental(Experimental.Kind.TRIGGER) |
| public class DefaultTrigger extends Trigger { |
| |
| private DefaultTrigger() { |
| super(); |
| } |
| |
| /** Returns the default trigger. */ |
| public static DefaultTrigger of() { |
| return new DefaultTrigger(); |
| } |
| |
| @Override |
| public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) { |
| return window.maxTimestamp(); |
| } |
| |
| @Override |
| public boolean isCompatible(Trigger other) { |
| // Semantically, all default triggers are identical |
| return other instanceof DefaultTrigger; |
| } |
| |
| @Override |
| protected Trigger getContinuationTrigger(List<Trigger> continuationTriggers) { |
| return this; |
| } |
| } |