/**
* 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.loadbalancer;
import java.util.List;
import org.apache.camel.AsyncCallback;
import org.apache.camel.AsyncProcessor;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.impl.converter.AsyncProcessorTypeConverter;
import org.apache.camel.util.AsyncProcessorHelper;
/**
* A base class for {@link LoadBalancer} implementations which choose a single
* destination for each exchange (rather like JMS Queues)
*
* @version $Revision: 959391 $
*/
public abstract class QueueLoadBalancer extends LoadBalancerSupport {
public boolean process(final Exchange exchange, final AsyncCallback callback) {
boolean sync;
List<Processor> list = getProcessors();
if (list.isEmpty()) {
throw new IllegalStateException("No processors available to process " + exchange);
}
Processor processor = chooseProcessor(list, exchange);
if (processor == null) {
throw new IllegalStateException("No processors could be chosen to process " + exchange);
} else {
AsyncProcessor albp = AsyncProcessorTypeConverter.convert(processor);
sync = AsyncProcessorHelper.process(albp, exchange, new AsyncCallback() {
public void done(boolean doneSync) {
// only handle the async case
if (doneSync) {
return;
}
callback.done(false);
}
});
}
return sync;
}
public void process(Exchange exchange) throws Exception {
AsyncProcessorHelper.process(this, exchange);
}
protected abstract Processor chooseProcessor(List<Processor> processors, Exchange exchange);
}