001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.mina.core.future;
021
022import java.util.concurrent.atomic.AtomicInteger;
023
024import org.apache.mina.core.IoUtil;
025
026/**
027 * An {@link IoFuture} of {@link IoFuture}s.  It is useful when you want to
028 * get notified when all {@link IoFuture}s are complete.  It is not recommended
029 * to use {@link CompositeIoFuture} if you just want to wait for all futures.
030 * In that case, please use {@link IoUtil#await(Iterable)} instead
031 * for better performance.
032 * 
033 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
034 *
035 * @param <E> the type of the child futures.
036 */
037public class CompositeIoFuture<E extends IoFuture> extends DefaultIoFuture {
038
039    private final NotifyingListener listener = new NotifyingListener();
040
041    private final AtomicInteger unnotified = new AtomicInteger();
042
043    private volatile boolean constructionFinished;
044
045    public CompositeIoFuture(Iterable<E> children) {
046        super(null);
047
048        for (E f : children) {
049            f.addListener(listener);
050            unnotified.incrementAndGet();
051        }
052
053        constructionFinished = true;
054        if (unnotified.get() == 0) {
055            setValue(true);
056        }
057    }
058
059    private class NotifyingListener implements IoFutureListener<IoFuture> {
060        public void operationComplete(IoFuture future) {
061            if (unnotified.decrementAndGet() == 0 && constructionFinished) {
062                setValue(true);
063            }
064        }
065    }
066}