/**
* 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.activemq.transport;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.apache.activemq.command.Command;
import org.apache.activemq.command.ExceptionResponse;
import org.apache.activemq.command.Response;
import org.apache.activemq.util.IntSequenceGenerator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Adds the incrementing sequence number to commands along with performing the
* corelation of responses to requests to create a blocking request-response
* semantics.
*
* @version $Revision: 1.4 $
*/
public class ResponseCorrelator extends TransportFilter {
private static final Log LOG = LogFactory.getLog(ResponseCorrelator.class);
private final Map<Integer, FutureResponse> requestMap = new HashMap<Integer, FutureResponse>();
private IntSequenceGenerator sequenceGenerator;
private final boolean debug = LOG.isDebugEnabled();
public ResponseCorrelator(Transport next) {
this(next, new IntSequenceGenerator());
}
public ResponseCorrelator(Transport next, IntSequenceGenerator sequenceGenerator) {
super(next);
this.sequenceGenerator = sequenceGenerator;
}
public void oneway(Object o) throws IOException {
Command command = (Command)o;
command.setCommandId(sequenceGenerator.getNextSequenceId());
command.setResponseRequired(false);
next.oneway(command);
}
public FutureResponse asyncRequest(Object o, ResponseCallback responseCallback) throws IOException {
Command command = (Command)o;
command.setCommandId(sequenceGenerator.getNextSequenceId());
command.setResponseRequired(true);
FutureResponse future = new FutureResponse(responseCallback);
synchronized (requestMap) {
requestMap.put(new Integer(command.getCommandId()), future);
}
next.oneway(command);
return future;
}
public Object request(Object command) throws IOException {
FutureResponse response = asyncRequest(command, null);
return response.getResult();
}
public Object request(Object command, int timeout) throws IOException {
FutureResponse response = asyncRequest(command, null);
return response.getResult(timeout);
}
public void onCommand(Object o) {
Command command = (Command)o;
if (command.isResponse()) {
Response response = (Response)command;
FutureResponse future = null;
synchronized (requestMap) {
future = requestMap.remove(Integer.valueOf(response.getCorrelationId()));
}
if (future != null) {
future.set(response);
} else {
if (debug) {
LOG.debug("Received unexpected response for command id: " + response.getCorrelationId());
}
}
} else {
getTransportListener().onCommand(command);
}
}
/**
* If an async exception occurs, then assume no responses will arrive for
* any of current requests. Lets let them know of the problem.
*/
public void onException(IOException error) {
// Copy and Clear the request Map
ArrayList<FutureResponse> requests = new ArrayList<FutureResponse>(requestMap.values());
requestMap.clear();
for (Iterator<FutureResponse> iter = requests.iterator(); iter.hasNext();) {
FutureResponse fr = iter.next();
fr.set(new ExceptionResponse(error));
}
super.onException(error);
}
public IntSequenceGenerator getSequenceGenerator() {
return sequenceGenerator;
}
public String toString() {
return next.toString();
}
}