/**
* 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;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import org.apache.camel.AsyncCallback;
import org.apache.camel.AsyncProcessor;
import org.apache.camel.CamelContext;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.impl.DefaultExchange;
import org.apache.camel.impl.converter.AsyncProcessorTypeConverter;
import org.apache.camel.util.AsyncProcessorHelper;
import org.apache.camel.util.ExchangeHelper;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Creates a Pipeline pattern where the output of the previous step is sent as
* input to the next step, reusing the same message exchanges
*
* @version $Revision: 959398 $
*/
public class Pipeline extends MulticastProcessor implements AsyncProcessor, Traceable {
private static final transient Log LOG = LogFactory.getLog(Pipeline.class);
public Pipeline(CamelContext camelContext, Collection<Processor> processors) {
super(camelContext, processors);
}
public static Processor newInstance(CamelContext camelContext, List<Processor> processors) {
if (processors.isEmpty()) {
return null;
} else if (processors.size() == 1) {
return processors.get(0);
}
return new Pipeline(camelContext, processors);
}
public void process(Exchange exchange) throws Exception {
AsyncProcessorHelper.process(this, exchange);
}
public boolean process(Exchange exchange, AsyncCallback callback) {
Iterator<Processor> processors = getProcessors().iterator();
Exchange nextExchange = exchange;
boolean first = true;
while (continueRouting(processors, nextExchange)) {
if (first) {
first = false;
} else {
// prepare for next run
nextExchange = createNextExchange(nextExchange);
}
// get the next processor
Processor processor = processors.next();
AsyncProcessor async = AsyncProcessorTypeConverter.convert(processor);
boolean sync = process(exchange, nextExchange, callback, processors, async);
// continue as long its being processed synchronously
if (!sync) {
if (LOG.isTraceEnabled()) {
LOG.trace("Processing exchangeId: " + exchange.getExchangeId() + " is continued being processed asynchronously");
}
// the remainder of the pipeline will be completed async
// so we break out now, then the callback will be invoked which then continue routing from where we left here
return false;
}
if (LOG.isTraceEnabled()) {
LOG.trace("Processing exchangeId: " + exchange.getExchangeId() + " is continued being processed synchronously");
}
// check for error if so we should break out
boolean exceptionHandled = hasExceptionBeenHandledByErrorHandler(nextExchange);
if (nextExchange.isFailed() || nextExchange.isRollbackOnly() || exceptionHandled) {
// The Exchange.ERRORHANDLED_HANDLED property is only set if satisfactory handling was done
// by the error handler. It's still an exception, the exchange still failed.
if (LOG.isDebugEnabled()) {
StringBuilder sb = new StringBuilder();
sb.append("Message exchange has failed so breaking out of pipeline: ").append(nextExchange);
if (nextExchange.isRollbackOnly()) {
sb.append(" Marked as rollback only.");
}
if (nextExchange.getException() != null) {
sb.append(" Exception: ").append(nextExchange.getException());
}
if (nextExchange.hasOut() && nextExchange.getOut().isFault()) {
sb.append(" Fault: ").append(nextExchange.getOut());
}
if (exceptionHandled) {
sb.append(" Handled by the error handler.");
}
LOG.debug(sb.toString());
}
break;
}
}
if (LOG.isTraceEnabled()) {
// logging nextExchange as it contains the exchange that might have altered the payload and since
// we are logging the completion if will be confusing if we log the original instead
// we could also consider logging the original and the nextExchange then we have *before* and *after* snapshots
LOG.trace("Processing complete for exchangeId: " + exchange.getExchangeId() + " >>> " + nextExchange);
}
// copy results back to the original exchange
ExchangeHelper.copyResults(exchange, nextExchange);
callback.done(true);
return true;
}
private boolean process(final Exchange original, final Exchange exchange, final AsyncCallback callback,
final Iterator<Processor> processors, final AsyncProcessor asyncProcessor) {
if (LOG.isTraceEnabled()) {
// this does the actual processing so log at trace level
LOG.trace("Processing exchangeId: " + exchange.getExchangeId() + " >>> " + exchange);
}
// implement asynchronous routing logic in callback so we can have the callback being
// triggered and then continue routing where we left
boolean sync = AsyncProcessorHelper.process(asyncProcessor, exchange, new AsyncCallback() {
public void done(boolean doneSync) {
// we only have to handle async completion of the pipeline
if (doneSync) {
return;
}
// continue processing the pipeline asynchronously
Exchange nextExchange = exchange;
while (continueRouting(processors, nextExchange)) {
AsyncProcessor processor = AsyncProcessorTypeConverter.convert(processors.next());
// check for error if so we should break out
boolean exceptionHandled = hasExceptionBeenHandledByErrorHandler(nextExchange);
if (nextExchange.isFailed() || nextExchange.isRollbackOnly() || exceptionHandled) {
// The Exchange.ERRORHANDLED_HANDLED property is only set if satisfactory handling was done
// by the error handler. It's still an exception, the exchange still failed.
if (LOG.isDebugEnabled()) {
StringBuilder sb = new StringBuilder();
sb.append("Message exchange has failed so breaking out of pipeline: ").append(nextExchange);
if (nextExchange.isRollbackOnly()) {
sb.append(" Marked as rollback only.");
}
if (nextExchange.getException() != null) {
sb.append(" Exception: ").append(nextExchange.getException());
}
if (nextExchange.hasOut() && nextExchange.getOut().isFault()) {
sb.append(" Fault: ").append(nextExchange.getOut());
}
if (exceptionHandled) {
sb.append(" Handled by the error handler.");
}
LOG.debug(sb.toString());
}
break;
}
nextExchange = createNextExchange(nextExchange);
doneSync = process(original, nextExchange, callback, processors, processor);
if (!doneSync) {
if (LOG.isTraceEnabled()) {
LOG.trace("Processing exchangeId: " + exchange.getExchangeId() + " is continued being processed asynchronously");
}
return;
}
}
ExchangeHelper.copyResults(original, nextExchange);
if (LOG.isTraceEnabled()) {
LOG.trace("Processing complete for exchangeId: " + original.getExchangeId() + " >>> " + original);
}
callback.done(false);
}
});
return sync;
}
private static boolean hasExceptionBeenHandledByErrorHandler(Exchange nextExchange) {
return Boolean.TRUE.equals(nextExchange.getProperty(Exchange.ERRORHANDLER_HANDLED));
}
/**
* Strategy method to create the next exchange from the previous exchange.
* <p/>
* Remember to copy the original exchange id otherwise correlation of ids in the log is a problem
*
* @param previousExchange the previous exchange
* @return a new exchange
*/
protected Exchange createNextExchange(Exchange previousExchange) {
Exchange answer = new DefaultExchange(previousExchange);
// we must use the same id as this is a snapshot strategy where Camel copies a snapshot
// before processing the next step in the pipeline, so we have a snapshot of the exchange
// just before. This snapshot is used if Camel should do redeliveries (re try) using
// DeadLetterChannel. That is why it's important the id is the same, as it is the *same*
// exchange being routed.
answer.setExchangeId(previousExchange.getExchangeId());
answer.getProperties().putAll(previousExchange.getProperties());
// now lets set the input of the next exchange to the output of the
// previous message if it is not null
answer.setIn(previousExchange.hasOut()
? previousExchange.getOut().copy() : previousExchange.getIn().copy());
return answer;
}
protected boolean continueRouting(Iterator<Processor> it, Exchange exchange) {
Object stop = exchange.getProperty(Exchange.ROUTE_STOP);
if (stop != null) {
boolean doStop = exchange.getContext().getTypeConverter().convertTo(Boolean.class, stop);
if (doStop) {
if (LOG.isDebugEnabled()) {
LOG.debug("Exchange is marked to stop routing: " + exchange);
}
return false;
}
}
// continue if there are more processors to route
return it.hasNext();
}
@Override
public String toString() {
return "Pipeline[" + getProcessors() + "]";
}
@Override
public String getTraceLabel() {
return "pipeline";
}
}