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;
018
019 import java.util.concurrent.Callable;
020 import java.util.concurrent.ExecutorService;
021 import java.util.concurrent.Future;
022
023 import org.apache.camel.Exchange;
024 import org.apache.camel.Processor;
025 import org.apache.camel.WaitForTaskToComplete;
026 import org.apache.camel.util.ExchangeHelper;
027 import org.apache.camel.util.concurrent.ExecutorServiceHelper;
028
029 /**
030 * Threads processor that leverage a thread pool for processing exchanges.
031 * <p/>
032 * The original caller thread will receive a <tt>Future<Exchange></tt> in the OUT message body.
033 * It can then later use this handle to obtain the async response.
034 * <p/>
035 * Camel also provides type converters so you can just ask to get the desired object type and Camel
036 * will automatic wait for the async task to complete to return the response.
037 *
038 * @version $Revision: 792977 $
039 */
040 public class ThreadsProcessor extends DelegateProcessor implements Processor {
041
042 protected static final int DEFAULT_THREADPOOL_SIZE = 5;
043 protected ExecutorService executorService;
044 protected WaitForTaskToComplete waitForTaskToComplete;
045
046 public ThreadsProcessor(Processor output, ExecutorService executorService, WaitForTaskToComplete waitForTaskToComplete) {
047 super(output);
048 this.executorService = executorService;
049 this.waitForTaskToComplete = waitForTaskToComplete;
050 }
051
052 public void process(final Exchange exchange) throws Exception {
053 final Processor output = getProcessor();
054 if (output == null) {
055 // no output then return
056 return;
057 }
058
059 // use a new copy of the exchange to route async and handover the on completion to the new copy
060 // so its the new copy that performs the on completion callback when its done
061 final Exchange copy = exchange.copy(true);
062
063 // let it execute async and return the Future
064 Callable<Exchange> task = createTask(output, copy);
065
066 // sumbit the task
067 Future<Exchange> future = getExecutorService().submit(task);
068
069 // compute if we should wait for task to complete or not
070 WaitForTaskToComplete wait = waitForTaskToComplete;
071 if (exchange.getProperty(Exchange.ASYNC_WAIT) != null) {
072 wait = exchange.getProperty(Exchange.ASYNC_WAIT, WaitForTaskToComplete.class);
073 }
074
075 if (wait == WaitForTaskToComplete.Always) {
076 // wait for task to complete
077 Exchange response = future.get();
078 ExchangeHelper.copyResults(exchange, response);
079 } else if (wait == WaitForTaskToComplete.IfReplyExpected && ExchangeHelper.isOutCapable(exchange)) {
080 // wait for task to complete as we expect a reply
081 Exchange response = future.get();
082 ExchangeHelper.copyResults(exchange, response);
083 } else {
084 // no we do not expect a reply so lets continue, set a handle to the future task
085 // in case end user need it later
086 exchange.getOut().setBody(future);
087 }
088 }
089
090 protected Callable<Exchange> createTask(final Processor output, final Exchange copy) {
091 return new Callable<Exchange>() {
092 public Exchange call() throws Exception {
093 // must use a copy of the original exchange for processing async
094 output.process(copy);
095 return copy;
096 }
097 };
098 }
099
100 public ExecutorService getExecutorService() {
101 if (executorService == null) {
102 executorService = createExecutorService();
103 }
104 return executorService;
105 }
106
107 protected ExecutorService createExecutorService() {
108 return ExecutorServiceHelper.newScheduledThreadPool(DEFAULT_THREADPOOL_SIZE, "AsyncProcessor", true);
109 }
110
111 protected void doStop() throws Exception {
112 super.doStop();
113 if (executorService != null) {
114 executorService.shutdown();
115 }
116 }
117
118 public String toString() {
119 return "Threads";
120 }
121
122 }