| /* |
| * 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.joda.time.Instant; |
| |
| /** |
| * A {@link Trigger} that fires according to its subtrigger forever. |
| * |
| * <p>For example, to fire after the end of the window, and every time late data arrives: |
| * |
| * <pre>{@code |
| * Repeatedly.forever(AfterWatermark.pastEndOfWindow()); |
| * }</pre> |
| * |
| * <p>{@code Repeatedly.forever(someTrigger)} behaves like an infinite {@code |
| * AfterEach.inOrder(someTrigger, someTrigger, someTrigger, ...)}. |
| * |
| * <p>You can use {@link #orFinally(OnceTrigger)} to let another trigger interrupt the repetition. |
| */ |
| public class Repeatedly extends Trigger { |
| |
| private static final int REPEATED = 0; |
| |
| /** |
| * Create a composite trigger that repeatedly executes the trigger {@code repeated}, firing each |
| * time it fires and ignoring any indications to finish. |
| * |
| * <p>Unless used with {@link Trigger#orFinally} the composite trigger will never finish. |
| * |
| * @param repeated the trigger to execute repeatedly. |
| */ |
| public static Repeatedly forever(Trigger repeated) { |
| return new Repeatedly(repeated); |
| } |
| |
| private Trigger repeatedTrigger; |
| |
| private Repeatedly(Trigger repeatedTrigger) { |
| super(Arrays.asList(repeatedTrigger)); |
| this.repeatedTrigger = repeatedTrigger; |
| } |
| |
| public Trigger getRepeatedTrigger() { |
| return repeatedTrigger; |
| } |
| |
| @Override |
| public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) { |
| // This trigger fires once the repeated trigger fires. |
| return subTriggers.get(REPEATED).getWatermarkThatGuaranteesFiring(window); |
| } |
| |
| @Override |
| public boolean mayFinish() { |
| return false; |
| } |
| |
| @Override |
| protected Trigger getContinuationTrigger(List<Trigger> continuationTriggers) { |
| return new Repeatedly(continuationTriggers.get(REPEATED)); |
| } |
| |
| @Override |
| public String toString() { |
| return String.format("Repeatedly.forever(%s)", subTriggers.get(REPEATED)); |
| } |
| } |