/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.camel.processor;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.WaitForTaskToComplete;
import org.apache.camel.util.ExchangeHelper;
import org.apache.camel.util.concurrent.ExecutorServiceHelper;
/**
* Threads processor that leverage a thread pool for processing exchanges.
* <p/>
* The original caller thread will receive a <tt>Future<Exchange></tt> in the OUT message body.
* It can then later use this handle to obtain the async response.
* <p/>
* Camel also provides type converters so you can just ask to get the desired object type and Camel
* will automatic wait for the async task to complete to return the response.
*
* @version $Revision: 810364 $
*/
public class ThreadsProcessor extends DelegateProcessor implements Processor {
protected static final int DEFAULT_THREADPOOL_SIZE = 10;
protected ExecutorService executorService;
protected WaitForTaskToComplete waitForTaskToComplete;
public ThreadsProcessor(Processor output, ExecutorService executorService, WaitForTaskToComplete waitForTaskToComplete) {
super(output);
this.executorService = executorService;
this.waitForTaskToComplete = waitForTaskToComplete;
}
public void process(final Exchange exchange) throws Exception {
final Processor output = getProcessor();
if (output == null) {
// no output then return
return;
}
// use a new copy of the exchange to route async and handover the on completion to the new copy
// so its the new copy that performs the on completion callback when its done
final Exchange copy = ExchangeHelper.createCorrelatedCopy(exchange, true);
// let it execute async and return the Future
Callable<Exchange> task = createTask(output, copy);
// submit the task
Future<Exchange> future = getExecutorService().submit(task);
// compute if we should wait for task to complete or not
WaitForTaskToComplete wait = waitForTaskToComplete;
if (exchange.getProperty(Exchange.ASYNC_WAIT) != null) {
wait = exchange.getProperty(Exchange.ASYNC_WAIT, WaitForTaskToComplete.class);
}
if (wait == WaitForTaskToComplete.Always) {
// wait for task to complete
Exchange response = future.get();
ExchangeHelper.copyResults(exchange, response);
} else if (wait == WaitForTaskToComplete.IfReplyExpected && ExchangeHelper.isOutCapable(exchange)) {
// wait for task to complete as we expect a reply
Exchange response = future.get();
ExchangeHelper.copyResults(exchange, response);
} else {
// no we do not expect a reply so lets continue, set a handle to the future task
// in case end user need it later
exchange.getOut().setBody(future);
}
}
protected Callable<Exchange> createTask(final Processor output, final Exchange copy) {
return new Callable<Exchange>() {
public Exchange call() throws Exception {
// must use a copy of the original exchange for processing async
output.process(copy);
return copy;
}
};
}
public ExecutorService getExecutorService() {
if (executorService == null) {
executorService = createExecutorService();
}
return executorService;
}
protected ExecutorService createExecutorService() {
return ExecutorServiceHelper.newScheduledThreadPool(DEFAULT_THREADPOOL_SIZE, "Threads", true);
}
protected void doStop() throws Exception {
super.doStop();
if (executorService != null) {
executorService.shutdown();
// must null it so we can restart
executorService = null;
}
}
public String toString() {
return "Threads";
}
}