001 /*
002 * Copyright (C) 2008 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package com.google.common.util.concurrent;
018
019 import java.util.concurrent.Callable;
020 import java.util.concurrent.Executor;
021 import java.util.concurrent.FutureTask;
022
023 import javax.annotation.Nullable;
024
025 /**
026 * A {@link FutureTask} that also implements the {@link ListenableFuture}
027 * interface. Unlike {@code FutureTask}, {@code ListenableFutureTask} does not
028 * provide an overrideable {@link FutureTask#done() done()} method. For similar
029 * functionality, call {@link #addListener}.
030 *
031 * @author Sven Mawson
032 * @since 1.0
033 */
034 public final class ListenableFutureTask<V> extends FutureTask<V>
035 implements ListenableFuture<V> {
036
037 // The execution list to hold our listeners.
038 private final ExecutionList executionList = new ExecutionList();
039
040 /**
041 * Creates a {@code ListenableFutureTask} that will upon running, execute the
042 * given {@code Callable}.
043 *
044 * @param callable the callable task
045 * @since 10.0
046 */
047 public static <V> ListenableFutureTask<V> create(Callable<V> callable) {
048 return new ListenableFutureTask<V>(callable);
049 }
050
051 /**
052 * Creates a {@code ListenableFutureTask} that will upon running, execute the
053 * given {@code Runnable}, and arrange that {@code get} will return the
054 * given result on successful completion.
055 *
056 * @param runnable the runnable task
057 * @param result the result to return on successful completion. If you don't
058 * need a particular result, consider using constructions of the form:
059 * {@code ListenableFuture<?> f = ListenableFutureTask.create(runnable,
060 * null)}
061 * @since 10.0
062 */
063 public static <V> ListenableFutureTask<V> create(
064 Runnable runnable, @Nullable V result) {
065 return new ListenableFutureTask<V>(runnable, result);
066 }
067
068 private ListenableFutureTask(Callable<V> callable) {
069 super(callable);
070 }
071
072 private ListenableFutureTask(Runnable runnable, @Nullable V result) {
073 super(runnable, result);
074 }
075
076 @Override
077 public void addListener(Runnable listener, Executor exec) {
078 executionList.add(listener, exec);
079 }
080
081 /**
082 * Internal implementation detail used to invoke the listeners.
083 */
084 @Override
085 protected void done() {
086 executionList.execute();
087 }
088 }