001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.impl;
018
019 import java.util.concurrent.ArrayBlockingQueue;
020 import java.util.concurrent.BlockingQueue;
021 import java.util.concurrent.TimeUnit;
022
023 import org.apache.camel.Consumer;
024 import org.apache.camel.Endpoint;
025 import org.apache.camel.Exchange;
026 import org.apache.camel.Processor;
027 import org.apache.camel.processor.Logger;
028 import org.apache.camel.spi.ExceptionHandler;
029 import org.apache.commons.logging.Log;
030 import org.apache.commons.logging.LogFactory;
031
032 /**
033 * A default implementation of the {@link PollingConsumer} which uses the normal
034 * asynchronous consumer mechanism along with a {@link BlockingQueue} to allow
035 * the caller to pull messages on demand.
036 *
037 * @version $Revision: 1.1 $
038 */
039 public class DefaultPollingConsumer<E extends Exchange> extends PollingConsumerSupport<E> implements
040 Processor {
041 private static final transient Log LOG = LogFactory.getLog(DefaultPollingConsumer.class);
042 private BlockingQueue<E> queue;
043 private ExceptionHandler interuptedExceptionHandler = new LoggingExceptionHandler(new Logger(LOG));
044 private Consumer<E> consumer;
045
046 public DefaultPollingConsumer(Endpoint<E> endpoint) {
047 this(endpoint, new ArrayBlockingQueue<E>(1000));
048 }
049
050 public DefaultPollingConsumer(Endpoint<E> endpoint, BlockingQueue<E> queue) {
051 super(endpoint);
052 this.queue = queue;
053 }
054
055 public E receiveNoWait() {
056 return receive(0);
057 }
058
059 public E receive() {
060 while (!isStopping() && !isStopped()) {
061 try {
062 return queue.take();
063 } catch (InterruptedException e) {
064 handleInteruptedException(e);
065 }
066 }
067 return null;
068 }
069
070 public E receive(long timeout) {
071 try {
072 return queue.poll(timeout, TimeUnit.MILLISECONDS);
073 } catch (InterruptedException e) {
074 handleInteruptedException(e);
075 return null;
076 }
077 }
078
079 public void process(Exchange exchange) throws Exception {
080 queue.offer((E)exchange);
081 }
082
083 public ExceptionHandler getInteruptedExceptionHandler() {
084 return interuptedExceptionHandler;
085 }
086
087 public void setInteruptedExceptionHandler(ExceptionHandler interuptedExceptionHandler) {
088 this.interuptedExceptionHandler = interuptedExceptionHandler;
089 }
090
091 protected void handleInteruptedException(InterruptedException e) {
092 getInteruptedExceptionHandler().handleException(e);
093 }
094
095 protected void doStart() throws Exception {
096 // lets add ourselves as a consumer
097 consumer = getEndpoint().createConsumer(this);
098 consumer.start();
099 }
100
101 protected void doStop() throws Exception {
102 if (consumer != null) {
103 try {
104 consumer.stop();
105 } finally {
106 consumer = null;
107 }
108 }
109 }
110 }