PromiseCombiner.java — netty Source File

Source Code

/*
 * Copyright 2016 The Netty Project
 *
 * The Netty Project licenses this file to you 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:
 *
 *   https://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.netty.util.concurrent;

import io.netty.util.internal.ObjectUtil;

/**
 * <p>A promise combiner monitors the outcome of a number of discrete futures, then notifies a final, aggregate promise
 * when all of the combined futures are finished. The aggregate promise will succeed if and only if all of the combined
 * futures succeed. If any of the combined futures fail, the aggregate promise will fail. The cause failure for the
 * aggregate promise will be the failure for one of the failed combined futures; if more than one of the combined
 * futures fails, exactly which cause of failure will be assigned to the aggregate promise is undefined.</p>
 *
 * <p>Callers may populate a promise combiner with any number of futures to be combined via the
 * {@link PromiseCombiner#add(Future)} and {@link PromiseCombiner#addAll(Future[])} methods. When all futures to be
 * combined have been added, callers must provide an aggregate promise to be notified when all combined promises have
 * finished via the {@link PromiseCombiner#finish(Promise)} method.</p>
 *
 * <p>This implementation is <strong>NOT</strong> thread-safe and all methods must be called
 * from the {@link EventExecutor} thread.</p>
 */
public final class PromiseCombiner {
    private int expectedCount;
    private int doneCount;
    private Promise<Void> aggregatePromise;
    private Throwable cause;
    private final GenericFutureListener<Future<?>> listener = new GenericFutureListener<Future<?>>() {
        @Override
        public void operationComplete(final Future<?> future) {
            if (executor.inEventLoop()) {
                operationComplete0(future);
            } else {
                executor.execute(new Runnable() {
                    @Override
                    public void run() {
                        operationComplete0(future);
                    }
                });
            }
        }

        private void operationComplete0(Future<?> future) {
            assert executor.inEventLoop();
            ++doneCount;
            if (!future.isSuccess() && cause == null) {
                cause = future.cause();
            }
// ... (119 more lines)