org.apache.flink.streaming.connectors.rabbitmq.RMQSource.java Source code

Introduction

Here is the source code for org.apache.flink.streaming.connectors.rabbitmq.RMQSource.java

Source

/**
 *
 * 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.flink.streaming.connectors.rabbitmq;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.function.source.RichSourceFunction;
import org.apache.flink.util.Collector;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;

public abstract class RMQSource<OUT> extends RichSourceFunction<OUT> {
    private static final long serialVersionUID = 1L;

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

    private final String QUEUE_NAME;
    private final String HOST_NAME;
    private boolean closeWithoutSend = false;
    private boolean sendAndClose = false;

    private transient ConnectionFactory factory;
    private transient Connection connection;
    private transient Channel channel;
    private transient QueueingConsumer consumer;
    private transient QueueingConsumer.Delivery delivery;

    OUT outTuple;

    public RMQSource(String HOST_NAME, String QUEUE_NAME) {
        this.HOST_NAME = HOST_NAME;
        this.QUEUE_NAME = QUEUE_NAME;
    }

    /**
     * Initializes the connection to RMQ.
     */
    private void initializeConnection() {
        factory = new ConnectionFactory();
        factory.setHost(HOST_NAME);
        try {
            connection = factory.newConnection();
            channel = connection.createChannel();
            channel.queueDeclare(QUEUE_NAME, false, false, false, null);
            consumer = new QueueingConsumer(channel);
            channel.basicConsume(QUEUE_NAME, true, consumer);
        } catch (IOException e) {
            throw new RuntimeException("Cannot create RMQ connection with " + QUEUE_NAME + " at " + HOST_NAME, e);
        }
    }

    /**
     * Called to forward the data from the source to the {@link DataStream}.
     * 
     * @param collector
     *            The Collector for sending data to the dataStream
     */
    @Override
    public void invoke(Collector<OUT> collector) throws Exception {
        initializeConnection();

        while (true) {

            try {
                delivery = consumer.nextDelivery();
            } catch (Exception e) {
                if (LOG.isErrorEnabled()) {
                    LOG.error("Cannot receive RMQ message " + QUEUE_NAME + " at " + HOST_NAME);
                }
            }

            outTuple = deserialize(delivery.getBody());
            if (closeWithoutSend) {
                break;
            } else {
                collector.collect(outTuple);
            }
            if (sendAndClose) {
                break;
            }
        }

        try {
            connection.close();
        } catch (IOException e) {
            throw new RuntimeException("Error while closing RMQ connection with " + QUEUE_NAME + " at " + HOST_NAME,
                    e);
        }

    }

    /**
     * Deserializes the incoming data.
     * 
     * @param message
     *            The incoming message in a byte array
     * @return The deserialized message in the required format.
     */
    public abstract OUT deserialize(byte[] message);

    /**
     * Closes the connection immediately and no further data will be sent.
     */
    public void closeWithoutSend() {
        closeWithoutSend = true;
    }

    /**
     * Closes the connection only when the next message is sent after this call.
     */
    public void sendAndClose() {
        sendAndClose = true;
    }

}