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The Netty project is an effort to provide an asynchronous event-driven network application framework and tools for rapid development of maintainable high performance and high scalability protocol servers and clients. In other words, Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients. It greatly simplifies and streamlines network programming such as TCP and UDP socket server.

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/*
 * Copyright 2012 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:
 *
 *   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 org.jboss.netty.channel;

import static org.jboss.netty.channel.Channels.*;

/**
 * A skeletal {@link ChannelSink} implementation.
 */
public abstract class AbstractChannelSink implements ChannelSink {

    /**
     * Creates a new instance.
     */
    protected AbstractChannelSink() {
    }

    /**
     * Sends an {@link ExceptionEvent} upstream with the specified
     * {@code cause}.
     *
     * @param event the {@link ChannelEvent} which caused a
     *              {@link ChannelHandler} to raise an exception
     * @param cause the exception raised by a {@link ChannelHandler}
     */
    public void exceptionCaught(ChannelPipeline pipeline,
            ChannelEvent event, ChannelPipelineException cause) throws Exception {
        Throwable actualCause = cause.getCause();
        if (actualCause == null) {
            actualCause = cause;
        }
        if (isFireExceptionCaughtLater(event, actualCause)) {
            fireExceptionCaughtLater(event.getChannel(), actualCause);
        } else {
            fireExceptionCaught(event.getChannel(), actualCause);
        }
    }

    /**
     * Returns {@code true} if and only if the specified {@code actualCause}, which was raised while
     * handling the specified {@code event}, must trigger an {@code exceptionCaught()} event in
     * an I/O thread.
     *
     * @param event the event which raised exception
     * @param actualCause the raised exception
     */
    protected boolean isFireExceptionCaughtLater(ChannelEvent event, Throwable actualCause) {
        return false;
    }

    /**
     * This implementation just directly call {@link Runnable#run()}.
     * Sub-classes should override this if they can handle it in a better way
     */
    public ChannelFuture execute(ChannelPipeline pipeline, Runnable task) {
        try {
            task.run();
            return succeededFuture(pipeline.getChannel());
        } catch (Throwable t) {
            return failedFuture(pipeline.getChannel(), t);
        }
    }
}