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/*
* Copyright (C) 2008 The Guava Authors
*
* 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 com.google.common.util.concurrent;
import java.util.concurrent.Callable;
import java.util.concurrent.Executor;
import java.util.concurrent.FutureTask;
import javax.annotation.Nullable;
/**
* A {@link FutureTask} that also implements the {@link ListenableFuture}
* interface. Unlike {@code FutureTask}, {@code ListenableFutureTask} does not
* provide an overrideable {@link FutureTask#done() done()} method. For similar
* functionality, call {@link #addListener}.
*
* <p>
*
* @author Sven Mawson
* @since 1.0
*/
public class ListenableFutureTask<V> extends FutureTask<V>
implements ListenableFuture<V> {
// TODO(cpovirk): explore ways of making ListenableFutureTask final. There are
// some valid reasons such as BoundedQueueExecutorService to allow extends but it
// would be nice to make it final to avoid unintended usage.
// The execution list to hold our listeners.
private final ExecutionList executionList = new ExecutionList();
/**
* Creates a {@code ListenableFutureTask} that will upon running, execute the
* given {@code Callable}.
*
* @param callable the callable task
* @since 10.0
*/
public static <V> ListenableFutureTask<V> create(Callable<V> callable) {
return new ListenableFutureTask<V>(callable);
}
/**
* Creates a {@code ListenableFutureTask} that will upon running, execute the
* given {@code Runnable}, and arrange that {@code get} will return the
* given result on successful completion.
*
* @param runnable the runnable task
* @param result the result to return on successful completion. If you don't
* need a particular result, consider using constructions of the form:
* {@code ListenableFuture<?> f = ListenableFutureTask.create(runnable,
* null)}
* @since 10.0
*/
public static <V> ListenableFutureTask<V> create(
Runnable runnable, @Nullable V result) {
return new ListenableFutureTask<V>(runnable, result);
}
ListenableFutureTask(Callable<V> callable) {
super(callable);
}
ListenableFutureTask(Runnable runnable, @Nullable V result) {
super(runnable, result);
}
@Override
public void addListener(Runnable listener, Executor exec) {
executionList.add(listener, exec);
}
/**
* Internal implementation detail used to invoke the listeners.
*/
@Override
protected void done() {
executionList.execute();
}
}
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