001 /**
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one or more
004 * contributor license agreements. See the NOTICE file distributed with
005 * this work for additional information regarding copyright ownership.
006 * The ASF licenses this file to You under the Apache License, Version 2.0
007 * (the "License"); you may not use this file except in compliance with
008 * the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 package org.apache.camel.impl;
019
020 import org.apache.camel.Consumer;
021 import org.apache.camel.Endpoint;
022 import org.apache.camel.Exchange;
023 import org.apache.camel.Processor;
024 import org.apache.camel.PollingConsumer;
025 import org.apache.camel.processor.Logger;
026 import org.apache.camel.spi.ExceptionHandler;
027 import org.apache.commons.logging.Log;
028 import org.apache.commons.logging.LogFactory;
029
030 import java.util.concurrent.ArrayBlockingQueue;
031 import java.util.concurrent.BlockingQueue;
032 import java.util.concurrent.TimeUnit;
033
034 /**
035 * A default implementation of the {@link PollingConsumer} which uses the normal asynchronous consumer mechanism
036 * along with a {@link BlockingQueue} to allow the caller to pull messages on demand.
037 *
038 * @version $Revision: 1.1 $
039 */
040 public class DefaultPollingConsumer<E extends Exchange> extends PollingConsumerSupport<E> implements 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 }
064 catch (InterruptedException e) {
065 handleInteruptedException(e);
066 }
067 }
068 return null;
069 }
070
071 public E receive(long timeout) {
072 try {
073 return queue.poll(timeout, TimeUnit.MILLISECONDS);
074 }
075 catch (InterruptedException e) {
076 handleInteruptedException(e);
077 return null;
078 }
079 }
080
081 public void process(Exchange exchange) throws Exception {
082 queue.offer((E) exchange);
083 }
084
085 public ExceptionHandler getInteruptedExceptionHandler() {
086 return interuptedExceptionHandler;
087 }
088
089 public void setInteruptedExceptionHandler(ExceptionHandler interuptedExceptionHandler) {
090 this.interuptedExceptionHandler = interuptedExceptionHandler;
091 }
092
093 protected void handleInteruptedException(InterruptedException e) {
094 getInteruptedExceptionHandler().handleException(e);
095 }
096
097 protected void doStart() throws Exception {
098 // lets add ourselves as a consumer
099 consumer = getEndpoint().createConsumer(this);
100 consumer.start();
101 }
102
103 protected void doStop() throws Exception {
104 if (consumer != null) {
105 try {
106 consumer.stop();
107 }
108 finally {
109 consumer = null;
110 }
111 }
112 }
113 }