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 org.apache.camel.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: 789550 $ 038 */ 039 public class EventDrivenPollingConsumer extends PollingConsumerSupport implements Processor { 040 private static final transient Log LOG = LogFactory.getLog(EventDrivenPollingConsumer.class); 041 private BlockingQueue<Exchange> queue; 042 private ExceptionHandler interuptedExceptionHandler = new LoggingExceptionHandler(new Logger(LOG)); 043 private Consumer consumer; 044 045 public EventDrivenPollingConsumer(Endpoint endpoint) { 046 this(endpoint, new ArrayBlockingQueue<Exchange>(1000)); 047 } 048 049 public EventDrivenPollingConsumer(Endpoint endpoint, BlockingQueue<Exchange> queue) { 050 super(endpoint); 051 this.queue = queue; 052 } 053 054 public Exchange receiveNoWait() { 055 return receive(0); 056 } 057 058 public Exchange receive() { 059 while (isRunAllowed()) { 060 try { 061 return queue.take(); 062 } catch (InterruptedException e) { 063 handleInteruptedException(e); 064 } 065 } 066 if (LOG.isTraceEnabled()) { 067 LOG.trace("Consumer is not running, so returning null"); 068 } 069 return null; 070 } 071 072 public Exchange receive(long timeout) { 073 try { 074 return queue.poll(timeout, TimeUnit.MILLISECONDS); 075 } catch (InterruptedException e) { 076 handleInteruptedException(e); 077 return null; 078 } 079 } 080 081 public void process(Exchange exchange) throws Exception { 082 queue.offer(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 } finally { 108 consumer = null; 109 } 110 } 111 } 112 }