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    
024    /** 
025     * Handles calling the UnitOfWork.done() method when processing of an exchange
026     * is complete.
027     */
028    public final class UnitOfWorkProcessor extends DelegateAsyncProcessor {
029    
030        public UnitOfWorkProcessor(AsyncProcessor processor) {
031            super(processor);
032        }
033        
034        public boolean process(final Exchange exchange, final AsyncCallback callback) {
035            if (exchange.getUnitOfWork() == null) {
036                // If there is no existing UoW, then we should start one and
037                // terminate it once processing is completed for the exchange.
038                exchange.setUnitOfWork(new DefaultUnitOfWork());
039                return processor.process(exchange, new AsyncCallback() {
040                    public void done(boolean sync) {
041                        // Order here matters. We need to complete the callbacks
042                        // since they will likely update the exchange with 
043                        // some final results.
044                        callback.done(sync);
045                        exchange.getUnitOfWork().done(exchange);
046                        exchange.setUnitOfWork(null);
047                    }
048                });
049            } else {
050                // There was an existing UoW, so we should just pass through..
051                // so that the guy the initiated the UoW can terminate it.
052                return processor.process(exchange, callback);
053            }
054        }
055    
056    }