ListenableFutureTask.java

/*
 * Copyright 2002-2013 the original author or 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.xiongyingqi.util.concurrent;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

/**
 * Extension of {@link java.util.concurrent.FutureTask} that implements {@link ListenableFuture}.
 *
 * @author Arjen Poutsma
 * @since 4.0
 */
public class ListenableFutureTask<T> extends FutureTask<T>
        implements ListenableFuture<T> {

    private final ListenableFutureCallbackRegistry<T> callbacks =
            new ListenableFutureCallbackRegistry<T>();

    /**
     * Creates a new {@code ListenableFutureTask} that will, upon running, execute the
     * given {@link java.util.concurrent.Callable}.
     *
     * @param callable the callable task
     */
    public ListenableFutureTask(Callable<T> callable) {
        super(callable);
    }

    /**
     * Creates a {@code ListenableFutureTask} that will, upon running, execute the given
     * {@link Runnable}, and arrange that {@link #get()} will return the given result on
     * successful completion.
     *
     * @param runnable the runnable task
     * @param result   the result to return on successful completion
     */
    public ListenableFutureTask(Runnable runnable, T result) {
        super(runnable, result);
    }

    @Override
    public void addCallback(ListenableFutureCallback<? super T> callback) {
        callbacks.addCallback(callback);
    }

    @Override
    protected final void done() {
        Throwable cause;
        try {
            T result = get();
            callbacks.success(result);
            return;
        } catch (InterruptedException ex) {
            Thread.currentThread().interrupt();
            return;
        } catch (ExecutionException ex) {
            cause = ex.getCause();
            if (cause == null) {
                cause = ex;
            }
        } catch (Throwable t) {
            cause = t;
        }
        callbacks.failure(cause);
    }
}