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.processor.resequencer;
018
019 import java.lang.reflect.InvocationHandler;
020 import java.lang.reflect.Method;
021 import java.lang.reflect.Proxy;
022 import java.util.concurrent.BlockingQueue;
023
024 import org.apache.camel.Exchange;
025 import org.apache.camel.Processor;
026 import org.apache.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028
029 /**
030 * A thread that takes re-ordered {@link Exchange}s from a blocking queue and
031 * send them to the linked processor.
032 *
033 * @author Martin Krasser
034 *
035 * @version $Revision
036 */
037 public class SequenceSender extends Thread {
038
039 private static final transient Log LOG = LogFactory.getLog(SequenceSender.class);
040 private static final Exchange STOP = createStopSignal();
041
042 private BlockingQueue<Exchange> queue;
043 private Processor processor;
044
045 /**
046 * Creates a new {@link SequenceSender} thread.
047 *
048 * @param processor
049 * the processor to send re-ordered {@link Exchange}s.
050 */
051 public SequenceSender(Processor processor) {
052 this.processor = processor;
053 }
054
055 /**
056 * Sets the {@link BlockingQueue} to take messages from.
057 *
058 * @param queue
059 * the {@link BlockingQueue} to take messages from.
060 */
061 public void setQueue(BlockingQueue<Exchange> queue) {
062 this.queue = queue;
063 }
064
065 public void run() {
066 while (true) {
067 try {
068 Exchange exchange = queue.take();
069 if (exchange == STOP) {
070 LOG.info("exit processing loop after cancellation");
071 return;
072 }
073 processor.process(exchange);
074 } catch (InterruptedException e) {
075 LOG.info("exit processing loop after interrupt");
076 return;
077 } catch (Exception e) {
078 LOG.warn("exception during exchange processing");
079 }
080 }
081 }
082
083 /**
084 * Cancels this thread.
085 */
086 public void cancel() throws InterruptedException {
087 queue.put(STOP);
088 }
089
090 private static Exchange createStopSignal() {
091 return (Exchange)Proxy.newProxyInstance(SequenceSender.class.getClassLoader(),
092 new Class[] {Exchange.class}, createStopHandler());
093 }
094
095 private static InvocationHandler createStopHandler() {
096 return new InvocationHandler() {
097 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
098 throw new RuntimeException("illegal method invocation on stop signal");
099 }
100 };
101 }
102
103 }