| /* |
| * 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 static org.apache.beam.vendor.guava.v20_0.com.google.common.base.Preconditions.checkArgument; |
| |
| import java.util.Arrays; |
| import java.util.List; |
| import org.apache.beam.sdk.annotations.Experimental; |
| import org.apache.beam.vendor.guava.v20_0.com.google.common.base.Joiner; |
| import org.joda.time.Instant; |
| |
| /** |
| * A composite {@link Trigger} that executes its sub-triggers in order. Only one sub-trigger is |
| * executing at a time, and any time it fires the {@code AfterEach} fires. When the currently |
| * executing sub-trigger finishes, the {@code AfterEach} starts executing the next sub-trigger. |
| * |
| * <p>{@code AfterEach.inOrder(t1, t2, ...)} finishes when all of the sub-triggers have finished. |
| * |
| * <p>The following properties hold: |
| * |
| * <ul> |
| * <li>{@code AfterEach.inOrder(AfterEach.inOrder(a, b), c)} behaves the same as {@code |
| * AfterEach.inOrder(a, b, c)} and {@code AfterEach.inOrder(a, AfterEach.inOrder(b, c)}. |
| * <li>{@code AfterEach.inOrder(Repeatedly.forever(a), b)} behaves the same as {@code |
| * Repeatedly.forever(a)}, since the repeated trigger never finishes. |
| * </ul> |
| */ |
| @Experimental(Experimental.Kind.TRIGGER) |
| public class AfterEach extends Trigger { |
| |
| private AfterEach(List<Trigger> subTriggers) { |
| super(subTriggers); |
| checkArgument(subTriggers.size() > 1); |
| } |
| |
| /** Returns an {@code AfterEach} {@code Trigger} with the given subtriggers. */ |
| @SafeVarargs |
| public static AfterEach inOrder(Trigger... triggers) { |
| return new AfterEach(Arrays.asList(triggers)); |
| } |
| |
| /** Returns an {@code AfterEach} {@code Trigger} with the given subtriggers. */ |
| public static AfterEach inOrder(List<Trigger> triggers) { |
| return new AfterEach(triggers); |
| } |
| |
| @Override |
| public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) { |
| // This trigger will fire at least once when the first trigger in the sequence |
| // fires at least once. |
| return subTriggers.get(0).getWatermarkThatGuaranteesFiring(window); |
| } |
| |
| @Override |
| protected Trigger getContinuationTrigger(List<Trigger> continuationTriggers) { |
| return Repeatedly.forever(new AfterFirst(continuationTriggers)); |
| } |
| |
| @Override |
| public String toString() { |
| StringBuilder builder = new StringBuilder("AfterEach.inOrder("); |
| Joiner.on(", ").appendTo(builder, subTriggers); |
| builder.append(")"); |
| |
| return builder.toString(); |
| } |
| } |