/** * Copyright (c) 2016-present, RxJava Contributors. * * 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 io.reactivex.disposables; import java.util.concurrent.atomic.AtomicReference; import io.reactivex.annotations.Nullable; import io.reactivex.internal.disposables.DisposableHelper; /** * A Disposable container that allows atomically updating/replacing the contained * Disposable with another Disposable, disposing the old one when updating plus * handling the disposition when the container itself is disposed. */ public final class SerialDisposable implements Disposable { final AtomicReference<Disposable> resource; /** * Constructs an empty SerialDisposable. */ public SerialDisposable() { this.resource = new AtomicReference<Disposable>(); } /** * Constructs a SerialDisposable with the given initial Disposable instance. * @param initialDisposable the initial Disposable instance to use, null allowed */ public SerialDisposable(@Nullable Disposable initialDisposable) { this.resource = new AtomicReference<Disposable>(initialDisposable); } /** * Atomically: set the next disposable on this container and dispose the previous * one (if any) or dispose next if the container has been disposed. * @param next the Disposable to set, may be null * @return true if the operation succeeded, false if the container has been disposed * @see #replace(Disposable) */ public boolean set(@Nullable Disposable next) { return DisposableHelper.set(resource, next); } /** * Atomically: set the next disposable on this container but don't dispose the previous * one (if any) or dispose next if the container has been disposed. * @param next the Disposable to set, may be null * @return true if the operation succeeded, false if the container has been disposed * @see #set(Disposable) */ public boolean replace(@Nullable Disposable next) { return DisposableHelper.replace(resource, next); } /** * Returns the currently contained Disposable or null if this container is empty. * @return the current Disposable, may be null */ @Nullable public Disposable get() { Disposable d = resource.get(); if (d == DisposableHelper.DISPOSED) { return Disposables.disposed(); } return d; } @Override public void dispose() { DisposableHelper.dispose(resource); } @Override public boolean isDisposed() { return DisposableHelper.isDisposed(resource.get()); } }