at.ac.tuwien.dsg.cloud.utilities.messaging.lightweight.rabbitMq.RabbitMqConsumer.java Source code

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Here is the source code for at.ac.tuwien.dsg.cloud.utilities.messaging.lightweight.rabbitMq.RabbitMqConsumer.java

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/* 
 * Copyright 2015 Svetoslav Videnov <s.videnov@dsg.tuwien.ac.at>.
 *
 * 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 at.ac.tuwien.dsg.cloud.utilities.messaging.lightweight.rabbitMq;

import at.ac.tuwien.dsg.cloud.utilities.messaging.api.Consumer;
import at.ac.tuwien.dsg.cloud.utilities.messaging.api.Message;
import at.ac.tuwien.dsg.cloud.utilities.messaging.api.MessageReceivedListener;
import at.ac.tuwien.dsg.cloud.utilities.messaging.lightweight.rabbitMq.channel.ReceivingChannel;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.apache.commons.collections4.queue.CircularFifoQueue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *
 * @author Svetoslav Videnov <s.videnov@dsg.tuwien.ac.at>
 */
public class RabbitMqConsumer implements Consumer, Runnable {

    private static Logger logger = LoggerFactory.getLogger(RabbitMqConsumer.class);
    private HashMap<String, List<MessageReceivedListener>> messageListeners;
    private ExecutorService threadPool;
    private ReceivingChannel channel;
    private Queue<String> messageFifo;

    public RabbitMqConsumer(ReceivingChannel channel) {
        this.messageListeners = new HashMap<>();
        this.threadPool = Executors.newFixedThreadPool(1);
        this.channel = channel;
        this.messageFifo = new CircularFifoQueue<>(100);
    }

    @Override
    public RabbitMqConsumer withType(String type) {
        this.channel.bindType(type);
        logger.trace("Started listening to {}.", type);
        return this;
    }

    @Override
    public Message getMessage() {
        Message msg = this.channel.getDelivery();
        logger.trace("Received following message: {}", new String(msg.getMessage(), StandardCharsets.UTF_8));
        return msg;
    }

    @Override
    public RabbitMqConsumer addMessageReceivedListener(MessageReceivedListener listener) {
        List<MessageReceivedListener> list = null;

        synchronized (this.messageListeners) {
            if (this.messageListeners.containsKey(listener.getType())) {
                list = this.messageListeners.get(listener.getType());
            } else {
                list = new ArrayList<>();
                this.messageListeners.put(listener.getType(), list);
                this.withType(listener.getType());
            }

            if (this.messageListeners.size() == 1) {
                this.threadPool.execute(this);
            }
        }

        synchronized (list) {
            list.add(listener);
        }

        return this;
    }

    @Override
    public RabbitMqConsumer removeMessageReceivedListener(MessageReceivedListener listener) {
        synchronized (this.messageListeners) {
            if (!this.messageListeners.containsKey(listener.getType())) {
                return this;
            }

            List<MessageReceivedListener> list = this.messageListeners.get(listener.getType());

            synchronized (list) {
                list.remove(listener);
            }

            if (list.isEmpty()) {
                this.messageListeners.remove(listener.getType());
            }
        }
        return this;
    }

    private void fireForType(String type, Message msg) {
        List<MessageReceivedListener> list = null;
        synchronized (this.messageListeners) {
            list = this.messageListeners.get(type);
        }

        if (list != null) {
            synchronized (list) {
                list.forEach(listener -> {
                    listener.messageReceived(msg);
                });
            }
        }
    }

    private void fireMessageReceived(Message msg) {
        for (String type : msg.getTypes()) {
            this.fireForType(type, msg);
        }

        this.fireForType(MessageReceivedListener.defaultType, msg);
    }

    @Override
    public void run() {
        while (!this.messageListeners.isEmpty()) {
            Message msg = this.getMessage();

            if (this.messageFifo.contains(msg.getMessageKey())) {
                msg = null;
            }

            if (msg != null) {
                this.messageFifo.add(msg.getMessageKey());
                this.fireMessageReceived(msg);
            }
        }
    }
}