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 */
017package org.apache.camel.processor;
018
019import java.util.Collection;
020import java.util.Iterator;
021import java.util.List;
022
023import org.apache.camel.AsyncCallback;
024import org.apache.camel.AsyncProcessor;
025import org.apache.camel.CamelContext;
026import org.apache.camel.Exchange;
027import org.apache.camel.Processor;
028import org.apache.camel.Traceable;
029import org.apache.camel.spi.IdAware;
030import org.apache.camel.util.AsyncProcessorConverterHelper;
031import org.apache.camel.util.AsyncProcessorHelper;
032import org.apache.camel.util.ExchangeHelper;
033import org.slf4j.Logger;
034import org.slf4j.LoggerFactory;
035
036import static org.apache.camel.processor.PipelineHelper.continueProcessing;
037
038/**
039 * Creates a Pipeline pattern where the output of the previous step is sent as
040 * input to the next step, reusing the same message exchanges
041 *
042 * @version 
043 */
044public class Pipeline extends MulticastProcessor implements AsyncProcessor, Traceable, IdAware {
045    private static final Logger LOG = LoggerFactory.getLogger(Pipeline.class);
046
047    private String id;
048
049    public Pipeline(CamelContext camelContext, Collection<Processor> processors) {
050        super(camelContext, processors);
051    }
052
053    public static Processor newInstance(CamelContext camelContext, List<Processor> processors) {
054        if (processors.isEmpty()) {
055            return null;
056        } else if (processors.size() == 1) {
057            return processors.get(0);
058        }
059        return new Pipeline(camelContext, processors);
060    }
061
062    public void process(Exchange exchange) throws Exception {
063        AsyncProcessorHelper.process(this, exchange);
064    }
065
066    public boolean process(Exchange exchange, AsyncCallback callback) {
067        Iterator<Processor> processors = getProcessors().iterator();
068        Exchange nextExchange = exchange;
069        boolean first = true;
070
071        while (continueRouting(processors, nextExchange)) {
072            if (first) {
073                first = false;
074            } else {
075                // prepare for next run
076                nextExchange = createNextExchange(nextExchange);
077            }
078
079            // get the next processor
080            Processor processor = processors.next();
081
082            AsyncProcessor async = AsyncProcessorConverterHelper.convert(processor);
083            boolean sync = process(exchange, nextExchange, callback, processors, async);
084
085            // continue as long its being processed synchronously
086            if (!sync) {
087                LOG.trace("Processing exchangeId: {} is continued being processed asynchronously", exchange.getExchangeId());
088                // the remainder of the pipeline will be completed async
089                // so we break out now, then the callback will be invoked which then continue routing from where we left here
090                return false;
091            }
092
093            LOG.trace("Processing exchangeId: {} is continued being processed synchronously", exchange.getExchangeId());
094
095            // check for error if so we should break out
096            if (!continueProcessing(nextExchange, "so breaking out of pipeline", LOG)) {
097                break;
098            }
099        }
100
101        // logging nextExchange as it contains the exchange that might have altered the payload and since
102        // we are logging the completion if will be confusing if we log the original instead
103        // we could also consider logging the original and the nextExchange then we have *before* and *after* snapshots
104        LOG.trace("Processing complete for exchangeId: {} >>> {}", exchange.getExchangeId(), nextExchange);
105
106        // copy results back to the original exchange
107        ExchangeHelper.copyResults(exchange, nextExchange);
108
109        callback.done(true);
110        return true;
111    }
112
113    private boolean process(final Exchange original, final Exchange exchange, final AsyncCallback callback,
114                            final Iterator<Processor> processors, final AsyncProcessor asyncProcessor) {
115        // this does the actual processing so log at trace level
116        LOG.trace("Processing exchangeId: {} >>> {}", exchange.getExchangeId(), exchange);
117
118        // implement asynchronous routing logic in callback so we can have the callback being
119        // triggered and then continue routing where we left
120        //boolean sync = AsyncProcessorHelper.process(asyncProcessor, exchange,
121        boolean sync = asyncProcessor.process(exchange, new AsyncCallback() {
122            public void done(boolean doneSync) {
123                // we only have to handle async completion of the pipeline
124                if (doneSync) {
125                    return;
126                }
127
128                // continue processing the pipeline asynchronously
129                Exchange nextExchange = exchange;
130                while (continueRouting(processors, nextExchange)) {
131                    AsyncProcessor processor = AsyncProcessorConverterHelper.convert(processors.next());
132
133                    // check for error if so we should break out
134                    if (!continueProcessing(nextExchange, "so breaking out of pipeline", LOG)) {
135                        break;
136                    }
137
138                    nextExchange = createNextExchange(nextExchange);
139                    doneSync = process(original, nextExchange, callback, processors, processor);
140                    if (!doneSync) {
141                        LOG.trace("Processing exchangeId: {} is continued being processed asynchronously", exchange.getExchangeId());
142                        return;
143                    }
144                }
145
146                ExchangeHelper.copyResults(original, nextExchange);
147                LOG.trace("Processing complete for exchangeId: {} >>> {}", original.getExchangeId(), original);
148                callback.done(false);
149            }
150        });
151
152        return sync;
153    }
154
155    /**
156     * Strategy method to create the next exchange from the previous exchange.
157     * <p/>
158     * Remember to copy the original exchange id otherwise correlation of ids in the log is a problem
159     *
160     * @param previousExchange the previous exchange
161     * @return a new exchange
162     */
163    protected Exchange createNextExchange(Exchange previousExchange) {
164        return PipelineHelper.createNextExchange(previousExchange);
165    }
166
167    protected boolean continueRouting(Iterator<Processor> it, Exchange exchange) {
168        boolean answer = true;
169
170        Object stop = exchange.getProperty(Exchange.ROUTE_STOP);
171        if (stop != null) {
172            boolean doStop = exchange.getContext().getTypeConverter().convertTo(Boolean.class, stop);
173            if (doStop) {
174                LOG.debug("ExchangeId: {} is marked to stop routing: {}", exchange.getExchangeId(), exchange);
175                answer = false;
176            }
177        } else {
178            // continue if there are more processors to route
179            answer = it.hasNext();
180        }
181
182        LOG.trace("ExchangeId: {} should continue routing: {}", exchange.getExchangeId(), answer);
183        return answer;
184    }
185
186    @Override
187    public String toString() {
188        return "Pipeline[" + getProcessors() + "]";
189    }
190
191    @Override
192    public String getTraceLabel() {
193        return "pipeline";
194    }
195
196    public String getId() {
197        return id;
198    }
199
200    public void setId(String id) {
201        this.id = id;
202    }
203}