eu.stratosphere.runtime.io.network.netty.OutboundConnectionQueue.java Source code

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Here is the source code for eu.stratosphere.runtime.io.network.netty.OutboundConnectionQueue.java

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/***********************************************************************************************************************
 * Copyright (C) 2010-2014 by the Stratosphere project (http://stratosphere.eu)
 *
 * 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 eu.stratosphere.runtime.io.network.netty;

import eu.stratosphere.runtime.io.network.Envelope;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.ArrayDeque;
import java.util.concurrent.atomic.AtomicInteger;

public class OutboundConnectionQueue extends ChannelInboundHandlerAdapter implements ChannelFutureListener {

    private static final Log LOG = LogFactory.getLog(OutboundConnectionQueue.class);

    private final Channel channel;

    private final ArrayDeque<Envelope> queuedEnvelopes = new ArrayDeque<Envelope>();

    private final AtomicInteger numQueued = new AtomicInteger(0);

    public OutboundConnectionQueue(Channel channel) {
        this.channel = channel;

        channel.pipeline().addFirst(this);
    }

    /**
     * Enqueues an envelope so be sent later.
     * <p/>
     * This method is always invoked by the task thread that wants the envelope sent.
     *
     * @param env The envelope to be sent.
     */
    public void enqueue(Envelope env) {
        // the user event trigger ensure thread-safe hand-over of the envelope
        this.channel.pipeline().fireUserEventTriggered(env);
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object envelopeToEnqueue) throws Exception {
        boolean triggerWrite = this.queuedEnvelopes.isEmpty();

        this.queuedEnvelopes.addLast((Envelope) envelopeToEnqueue);
        this.numQueued.incrementAndGet();

        if (triggerWrite) {
            writeAndFlushNextEnvelopeIfPossible();
        }
    }

    @Override
    public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
        writeAndFlushNextEnvelopeIfPossible();
    }

    @Override
    public void operationComplete(ChannelFuture future) throws Exception {
        if (future.isSuccess()) {
            writeAndFlushNextEnvelopeIfPossible();
        } else if (future.cause() != null) {
            exceptionOccurred(future.cause());
        } else {
            exceptionOccurred(new Exception("Envelope send aborted."));
        }
    }

    public int getNumQueuedEnvelopes() {
        return this.numQueued.intValue();
    }

    public Channel getChannel() {
        return this.channel;
    }

    private void writeAndFlushNextEnvelopeIfPossible() {
        if (this.channel.isWritable() && !this.queuedEnvelopes.isEmpty()) {
            Envelope nextEnvelope = this.queuedEnvelopes.pollFirst();
            this.numQueued.decrementAndGet();

            this.channel.writeAndFlush(nextEnvelope).addListener(this);
        }
    }

    private void exceptionOccurred(Throwable t) throws Exception {
        LOG.error(String.format("An exception occurred in Channel %s: %s", this.channel, t.getMessage()));
        throw new Exception(t);
    }
}