subprojects/s4-comm/src/main/java/org/apache/s4/comm/QueueingEmitter.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.apache.s4.comm;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

import org.apache.s4.base.Emitter;
import org.apache.s4.base.EventMessage;

import com.google.inject.Inject;
import com.google.inject.name.Named;

public class QueueingEmitter implements Emitter, Runnable {
    private Emitter emitter;
    private BlockingQueue<MessageHolder> queue;
    private long dropCount = 0;
    private volatile Thread thread;

    @Inject
    public QueueingEmitter(@Named("ll") Emitter emitter, @Named("comm.queue_emmiter_size") int queueSize) {
        this.emitter = emitter;
        queue = new LinkedBlockingQueue<MessageHolder>(queueSize);
    }

    public long getDropCount() {
        return dropCount;
    }

    public void start() {
        if (thread != null) {
            throw new IllegalStateException("QueueingEmitter is already started");
        }
        thread = new Thread(this, "QueueingEmitter");
        thread.start();
    }

    public void stop() {
        if (thread == null) {
            throw new IllegalStateException("QueueingEmitter is already stopped");
        }
        thread.interrupt();
        thread = null;
    }

    @Override
    public boolean send(int partitionId, EventMessage message) {
        MessageHolder mh = new MessageHolder(partitionId, message);
        if (!queue.offer(mh)) {
            dropCount++;
            return true;
        } else {
            return false;
        }
    }

    public void run() {
        while (!Thread.interrupted()) {
            try {
                MessageHolder mh = queue.take();
                // System.out.println("QueueingEmitter: Sending message on low-level emitter");
                emitter.send(mh.getPartitionId(), mh.getMessage());
            } catch (InterruptedException ie) {
                Thread.currentThread().interrupt();
            }
        }
    }

    public int getPartitionCount() {
        return emitter.getPartitionCount();
    }

    class MessageHolder {
        private int partitionId;
        private EventMessage message;

        public int getPartitionId() {
            return partitionId;
        }

        public void setPartitionId(int partitionId) {
            this.partitionId = partitionId;
        }

        public EventMessage getMessage() {
            return message;
        }

        public void setMessage(EventMessage message) {
            this.message = message;
        }

        public MessageHolder(int partitionId, EventMessage message) {
            super();
            this.partitionId = partitionId;
            this.message = message;
        }
    }

    @Override
    public void close() {
        // TODO Auto-generated method stub

    }
}