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 org.apache.camel.AsyncCallback;
020    import org.apache.camel.AsyncProcessor;
021    import org.apache.camel.Exchange;
022    import org.apache.camel.impl.DefaultUnitOfWork;
023    import static org.apache.camel.util.ObjectHelper.wrapRuntimeCamelException;
024    
025    /** 
026     * Handles calling the UnitOfWork.done() method when processing of an exchange
027     * is complete.
028     */
029    public final class UnitOfWorkProcessor extends DelegateAsyncProcessor {
030    
031        public UnitOfWorkProcessor(AsyncProcessor processor) {
032            super(processor);
033        }
034        
035        public boolean process(final Exchange exchange, final AsyncCallback callback) {
036            if (exchange.getUnitOfWork() == null) {
037                // If there is no existing UoW, then we should start one and
038                // terminate it once processing is completed for the exchange.
039                final DefaultUnitOfWork uow = new DefaultUnitOfWork();
040                exchange.setUnitOfWork(uow);
041                try {
042                    uow.start();
043                } catch (Exception e) {
044                    throw wrapRuntimeCamelException(e);
045                }
046                // return the process code where we do stop and cleanup
047                return processor.process(exchange, new AsyncCallback() {
048                    public void done(boolean sync) {
049                        // Order here matters. We need to complete the callbacks
050                        // since they will likely update the exchange with 
051                        // some final results.
052                        callback.done(sync);
053                        exchange.getUnitOfWork().done(exchange);
054                        try {
055                            uow.stop();
056                        } catch (Exception e) {
057                            throw wrapRuntimeCamelException(e);
058                        }
059                        exchange.setUnitOfWork(null);
060                    }
061                });
062            } else {
063                // There was an existing UoW, so we should just pass through..
064                // so that the guy the initiated the UoW can terminate it.
065                return processor.process(exchange, callback);
066            }
067        }
068    
069    }