/** * Copyright 2014 Netflix, Inc. * * Licensed 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 rx.subscriptions; import java.util.concurrent.atomic.AtomicIntegerFieldUpdater; import rx.Observable; import rx.Subscription; import rx.functions.Action0; /** * Subscription that can be checked for status such as in a loop inside an {@link Observable} to exit the loop * if unsubscribed. */ public final class BooleanSubscription implements Subscription { private final Action0 action; volatile int unsubscribed; static final AtomicIntegerFieldUpdater<BooleanSubscription> UNSUBSCRIBED_UPDATER = AtomicIntegerFieldUpdater.newUpdater(BooleanSubscription.class, "unsubscribed"); public BooleanSubscription() { action = null; } private BooleanSubscription(Action0 action) { this.action = action; } /** * Creates a {@code BooleanSubscription} without unsubscribe behavior. * * @return the created {@code BooleanSubscription} */ public static BooleanSubscription create() { return new BooleanSubscription(); } /** * Creates a {@code BooleanSubscription} with a specified function to invoke upon unsubscribe. * * @param onUnsubscribe * an {@link Action0} to invoke upon unsubscribe * @return the created {@code BooleanSubscription} */ public static BooleanSubscription create(Action0 onUnsubscribe) { return new BooleanSubscription(onUnsubscribe); } @Override public boolean isUnsubscribed() { return unsubscribed != 0; } @Override public final void unsubscribe() { if (UNSUBSCRIBED_UPDATER.compareAndSet(this, 0, 1)) { if (action != null) { action.call(); } } } }