1 /* 2 * Copyright (C) 2018 The Dagger Authors. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package dagger.producers; 18 19 import static java.lang.annotation.ElementType.TYPE; 20 import static java.lang.annotation.RetentionPolicy.CLASS; 21 22 import dagger.internal.Beta; 23 import java.lang.annotation.Documented; 24 import java.lang.annotation.Retention; 25 import java.lang.annotation.Target; 26 27 /** 28 * Annotates a production component or subcomponent to specify its policy when a child component is 29 * cancelled. 30 * 31 * <p>When a future returned from an entry point on a production component is cancelled, the 32 * component is cancelled: all producers in the component (including those for other entry points) 33 * are cancelled. 34 * 35 * <p>When a child component is cancelled, its parent component <i>is not</i> cancelled unless the 36 * parent component is annotated with {@code @CancellationPolicy(fromSubcomponents = PROPAGATE)}. If 37 * that parent component has a parent (the grandparent of the cancelled child component), it will 38 * not be cancelled unless it also has a {@code @CancellationPolicy} annotation allowing 39 * cancellation to propagate to it from subcomponents. 40 */ 41 @Documented 42 @Target(TYPE) 43 @Retention(CLASS) 44 @Beta 45 public @interface CancellationPolicy { 46 /** 47 * Defines whether the annotated production component is cancelled when a child component is 48 * cancelled. 49 * 50 * <p>The default, if no cancellation policy annotation is provided, is {@link 51 * Propagation#IGNORE}. 52 */ fromSubcomponents()53 Propagation fromSubcomponents(); 54 55 /** 56 * Enumeration of the options for what happens to a parent component when one of its child 57 * components is cancelled. 58 */ 59 enum Propagation { 60 /** Cancel the annotated component when a child component is cancelled. */ 61 PROPAGATE, 62 63 /** Do not cancel the annotated component when a child component is cancelled. */ 64 IGNORE 65 } 66 } 67