JMSMessageConsumer.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.flume.source.jms;

import java.util.ArrayList;
import java.util.List;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.Session;

import org.apache.flume.Event;
import org.apache.flume.FlumeException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;

class JMSMessageConsumer {
  private static final Logger logger = LoggerFactory
      .getLogger(JMSMessageConsumer.class);

  private final int batchSize;
  private final long pollTimeout;
  private final JMSMessageConverter messageConverter;

  private final Connection connection;
  private final Session session;
  private final Destination destination;
  private final MessageConsumer messageConsumer;

  JMSMessageConsumer(ConnectionFactory connectionFactory,
      String destinationName, JMSDestinationType destinationType,
      String messageSelector, int batchSize, long pollTimeout,
      JMSMessageConverter messageConverter, Optional<String> userName,
      Optional<String> password) {
    this.batchSize = batchSize;
    this.pollTimeout = pollTimeout;
    this.messageConverter = messageConverter;
    Preconditions.checkArgument(batchSize > 0, "Batch size must be greater "
        + "than zero");
    Preconditions.checkArgument(pollTimeout >= 0, "Poll timeout cannot be " +
        "negative");
    try {
      if(userName.isPresent()) {
        connection = connectionFactory.createConnection(userName.get(),
            password.get());
      } else {
        connection = connectionFactory.createConnection();
      }
      connection.start();
    } catch (JMSException e) {
      throw new FlumeException("Could not create connection to broker", e);
    }

    try {
      session = connection.createSession(true, Session.SESSION_TRANSACTED);
    } catch (JMSException e) {
      throw new FlumeException("Could not create session", e);
    }
    try {
      switch (destinationType) {
        case QUEUE:
          destination = session.createQueue(destinationName);
          break;
        case TOPIC:
          destination = session.createTopic(destinationName);
          break;
        default:
          throw new IllegalStateException(String.valueOf(destinationType));
      }
    } catch (JMSException e) {
      throw new FlumeException("Could not create destination "
          + destinationName, e);
    }

    try {
      messageConsumer = session.createConsumer(destination,
          messageSelector.isEmpty() ? null: messageSelector);
    } catch (JMSException e) {
      throw new FlumeException("Could not create consumer", e);
    }
    String startupMsg = String.format("Connected to '%s' of type '%s' with " +
        "user '%s', batch size '%d', selector '%s' ", destinationName,
        destinationType, userName.isPresent() ? userName.get() : "null",
            batchSize, messageSelector.isEmpty() ? null : messageSelector);
    logger.info(startupMsg);
  }

  List<Event> take() throws JMSException {
    List<Event> result = new ArrayList<Event>(batchSize);
    Message message;
    message = messageConsumer.receive(pollTimeout);
    if(message != null) {
      result.addAll(messageConverter.convert(message));
      int max = batchSize - 1;
      for (int i = 0; i < max; i++) {
        message = messageConsumer.receiveNoWait();
        if(message == null) {
          break;
        }
        result.addAll(messageConverter.convert(message));
      }
    }
    if(logger.isDebugEnabled()) {
      logger.debug(String.format("Took batch of %s from %s", result.size(),
          destination));
    }
    return result;
  }
  void commit() {
    try {
      session.commit();
    } catch (JMSException jmsException) {
      logger.warn("JMS Exception processing commit", jmsException);
    }
  }

  void rollback() {
    try {
      session.rollback();
    } catch (JMSException jmsException) {
      logger.warn("JMS Exception processing rollback", jmsException);
    }
  }

  void close() {
    try {
      if (session != null) {
        session.close();
      }
    } catch (JMSException e) {
      logger.error("Could not destroy session", e);
    }
    try {
      if (connection != null) {
        connection.close();
      }
    } catch (JMSException e) {
      logger.error("Could not destroy connection", e);
    }
  }
}