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.PollingConsumerAware; 027 import org.apache.camel.Processor; 028 import org.apache.camel.processor.Logger; 029 import org.apache.camel.spi.ExceptionHandler; 030 import org.apache.commons.logging.Log; 031 import org.apache.commons.logging.LogFactory; 032 033 /** 034 * A default implementation of the {@link org.apache.camel.PollingConsumer} which uses the normal 035 * asynchronous consumer mechanism along with a {@link BlockingQueue} to allow 036 * the caller to pull messages on demand. 037 * 038 * @version $Revision: 761579 $ 039 */ 040 public class EventDrivenPollingConsumer extends PollingConsumerSupport implements Processor { 041 private static final transient Log LOG = LogFactory.getLog(EventDrivenPollingConsumer.class); 042 private BlockingQueue<Exchange> queue; 043 private ExceptionHandler interuptedExceptionHandler = new LoggingExceptionHandler(new Logger(LOG)); 044 private Consumer consumer; 045 046 public EventDrivenPollingConsumer(Endpoint endpoint) { 047 this(endpoint, new ArrayBlockingQueue<Exchange>(1000)); 048 } 049 050 public EventDrivenPollingConsumer(Endpoint endpoint, BlockingQueue<Exchange> queue) { 051 super(endpoint); 052 this.queue = queue; 053 } 054 055 public Exchange receiveNoWait() { 056 return receive(0); 057 } 058 059 public Exchange receive() { 060 while (isRunAllowed()) { 061 try { 062 return queue.take(); 063 } catch (InterruptedException e) { 064 handleInteruptedException(e); 065 } 066 } 067 if (LOG.isTraceEnabled()) { 068 LOG.trace("Consumer is not running, so returning null"); 069 } 070 return null; 071 } 072 073 public Exchange receive(long timeout) { 074 try { 075 return queue.poll(timeout, TimeUnit.MILLISECONDS); 076 } catch (InterruptedException e) { 077 handleInteruptedException(e); 078 return null; 079 } 080 } 081 082 public void process(Exchange exchange) throws Exception { 083 if (exchange instanceof PollingConsumerAware) { 084 // callback that this exchange has been polled 085 ((PollingConsumerAware)exchange).exchangePolled(exchange); 086 } 087 queue.offer(exchange); 088 } 089 090 public ExceptionHandler getInteruptedExceptionHandler() { 091 return interuptedExceptionHandler; 092 } 093 094 public void setInteruptedExceptionHandler(ExceptionHandler interuptedExceptionHandler) { 095 this.interuptedExceptionHandler = interuptedExceptionHandler; 096 } 097 098 protected void handleInteruptedException(InterruptedException e) { 099 getInteruptedExceptionHandler().handleException(e); 100 } 101 102 protected void doStart() throws Exception { 103 // lets add ourselves as a consumer 104 consumer = getEndpoint().createConsumer(this); 105 consumer.start(); 106 } 107 108 protected void doStop() throws Exception { 109 if (consumer != null) { 110 try { 111 consumer.stop(); 112 } finally { 113 consumer = null; 114 } 115 } 116 } 117 }