/**
* 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.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.camel.CamelExchangeException;
import org.apache.camel.Exchange;
import org.apache.camel.Navigate;
import org.apache.camel.Processor;
import org.apache.camel.Producer;
import org.apache.camel.builder.ErrorHandlerBuilder;
import org.apache.camel.impl.ServiceSupport;
import org.apache.camel.processor.aggregate.AggregationStrategy;
import org.apache.camel.spi.RouteContext;
import org.apache.camel.spi.TracedRouteNodes;
import org.apache.camel.util.ExchangeHelper;
import org.apache.camel.util.ServiceHelper;
import org.apache.camel.util.concurrent.AtomicExchange;
import org.apache.camel.util.concurrent.ExecutorServiceHelper;
import org.apache.camel.util.concurrent.SubmitOrderedCompletionService;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import static org.apache.camel.util.ObjectHelper.notNull;
/**
* Implements the Multicast pattern to send a message exchange to a number of
* endpoints, each endpoint receiving a copy of the message exchange.
*
* @see Pipeline
* @version $Revision: 894829 $
*/
public class MulticastProcessor extends ServiceSupport implements Processor, Navigate<Processor>, Traceable {
private static final int DEFAULT_THREADPOOL_SIZE = 10;
private static final transient Log LOG = LogFactory.getLog(MulticastProcessor.class);
/**
* Class that represent each step in the multicast route to do
*/
static class ProcessorExchangePair {
private final Processor processor;
private final Exchange exchange;
public ProcessorExchangePair(Processor processor, Exchange exchange) {
this.processor = processor;
this.exchange = exchange;
}
public Processor getProcessor() {
return processor;
}
public Exchange getExchange() {
return exchange;
}
}
private Collection<Processor> processors;
private final AggregationStrategy aggregationStrategy;
private final boolean isParallelProcessing;
private final boolean streaming;
private final boolean stopOnException;
private ExecutorService executorService;
public MulticastProcessor(Collection<Processor> processors) {
this(processors, null);
}
public MulticastProcessor(Collection<Processor> processors, AggregationStrategy aggregationStrategy) {
this(processors, aggregationStrategy, false, null, false, false);
}
public MulticastProcessor(Collection<Processor> processors, AggregationStrategy aggregationStrategy,
boolean parallelProcessing, ExecutorService executorService, boolean streaming, boolean stopOnException) {
notNull(processors, "processors");
this.processors = processors;
this.aggregationStrategy = aggregationStrategy;
this.isParallelProcessing = parallelProcessing;
this.executorService = executorService;
this.streaming = streaming;
this.stopOnException = stopOnException;
if (isParallelProcessing()) {
if (this.executorService == null) {
// setup default executor as parallel processing requires an executor
this.executorService = ExecutorServiceHelper.newScheduledThreadPool(DEFAULT_THREADPOOL_SIZE, "Multicast", true);
}
}
}
@Override
public String toString() {
return "Multicast[" + getProcessors() + "]";
}
public String getTraceLabel() {
return "multicast";
}
public void process(Exchange exchange) throws Exception {
final AtomicExchange result = new AtomicExchange();
final Iterable<ProcessorExchangePair> pairs = createProcessorExchangePairs(exchange);
// multicast uses fine grained error handling on the output processors
// so use try .. catch to cater for this
try {
if (isParallelProcessing()) {
doProcessParallel(result, pairs, isStreaming());
} else {
doProcessSequential(result, pairs);
}
if (result.get() != null) {
ExchangeHelper.copyResults(exchange, result.get());
}
} catch (Exception e) {
// multicast uses error handling on its output processors and they have tried to redeliver
// so we shall signal back to the other error handlers that we are exhausted and they should not
// also try to redeliver as we will then do that twice
exchange.setProperty(Exchange.REDELIVERY_EXHAUSTED, Boolean.TRUE);
exchange.setException(e);
}
}
protected void doProcessParallel(final AtomicExchange result, Iterable<ProcessorExchangePair> pairs, boolean streaming) throws InterruptedException, ExecutionException {
final CompletionService<Exchange> completion;
final AtomicBoolean running = new AtomicBoolean(true);
if (streaming) {
// execute tasks in parallel+streaming and aggregate in the order they are finished (out of order sequence)
completion = new ExecutorCompletionService<Exchange>(executorService);
} else {
// execute tasks in parallel and aggregate in the order the tasks are submitted (in order sequence)
completion = new SubmitOrderedCompletionService<Exchange>(executorService);
}
final AtomicInteger total = new AtomicInteger(0);
for (ProcessorExchangePair pair : pairs) {
final Processor producer = pair.getProcessor();
final Exchange subExchange = pair.getExchange();
updateNewExchange(subExchange, total.intValue(), pairs);
completion.submit(new Callable<Exchange>() {
public Exchange call() throws Exception {
if (!running.get()) {
// do not start processing the task if we are not running
return subExchange;
}
doProcess(producer, subExchange);
// should we stop in case of an exception occurred during processing?
if (stopOnException && subExchange.getException() != null) {
// signal to stop running
running.set(false);
throw new CamelExchangeException("Parallel processing failed for number " + total.intValue(), subExchange, subExchange.getException());
}
if (LOG.isTraceEnabled()) {
LOG.trace("Parallel processing complete for exchange: " + subExchange);
}
return subExchange;
}
});
total.incrementAndGet();
}
for (int i = 0; i < total.intValue(); i++) {
Future<Exchange> future = completion.take();
Exchange subExchange = future.get();
if (aggregationStrategy != null) {
doAggregate(result, subExchange);
}
}
if (LOG.isDebugEnabled()) {
LOG.debug("Done parallel processing " + total + " exchanges");
}
}
protected void doProcessSequential(AtomicExchange result, Iterable<ProcessorExchangePair> pairs) throws Exception {
int total = 0;
for (ProcessorExchangePair pair : pairs) {
Processor producer = pair.getProcessor();
Exchange subExchange = pair.getExchange();
updateNewExchange(subExchange, total, pairs);
doProcess(producer, subExchange);
// should we stop in case of an exception occurred during processing?
if (stopOnException && subExchange.getException() != null) {
throw new CamelExchangeException("Sequential processing failed for number " + total, subExchange, subExchange.getException());
}
if (LOG.isTraceEnabled()) {
LOG.trace("Sequential processing complete for number " + total + " exchange: " + subExchange);
}
if (aggregationStrategy != null) {
doAggregate(result, subExchange);
}
total++;
}
if (LOG.isDebugEnabled()) {
LOG.debug("Done sequential processing " + total + " exchanges");
}
}
private void doProcess(Processor producer, Exchange exchange) {
TracedRouteNodes traced = exchange.getUnitOfWork() != null ? exchange.getUnitOfWork().getTracedRouteNodes() : null;
try {
// prepare tracing starting from a new block
if (traced != null) {
traced.pushBlock();
}
// set property which endpoint we send to
setToEndpoint(exchange, producer);
if (exchange.getUnitOfWork() != null && exchange.getUnitOfWork().getRouteContext() != null) {
// wrap the producer in error handler so we have fine grained error handling on
// the output side instead of the input side
// this is needed to support redelivery on that output alone and not doing redelivery
// for the entire multicast block again which will start from scratch again
RouteContext routeContext = exchange.getUnitOfWork().getRouteContext();
ErrorHandlerBuilder builder = routeContext.getRoute().getErrorHandlerBuilder();
// create error handler (create error handler directly to keep it light weight,
// instead of using ProcessorDefinition.wrapInErrorHandler)
producer = builder.createErrorHandler(routeContext, producer);
}
// let the producer process it
producer.process(exchange);
} catch (Exception e) {
exchange.setException(e);
} finally {
// pop the block so by next round we have the same staring point and thus the tracing looks accurate
if (traced != null) {
traced.popBlock();
}
}
}
/**
* Aggregate the {@link Exchange} with the current result
*
* @param result the current result
* @param exchange the exchange to be added to the result
*/
protected synchronized void doAggregate(AtomicExchange result, Exchange exchange) {
if (aggregationStrategy != null) {
// prepare the exchanges for aggregation
Exchange oldExchange = result.get();
ExchangeHelper.prepareAggregation(oldExchange, exchange);
result.set(aggregationStrategy.aggregate(oldExchange, exchange));
}
}
protected void updateNewExchange(Exchange exchange, int index, Iterable<ProcessorExchangePair> allPairs) {
exchange.setProperty(Exchange.MULTICAST_INDEX, index);
}
protected Iterable<ProcessorExchangePair> createProcessorExchangePairs(Exchange exchange) {
List<ProcessorExchangePair> result = new ArrayList<ProcessorExchangePair>(processors.size());
for (Processor processor : processors) {
Exchange copy = exchange.copy();
result.add(new ProcessorExchangePair(processor, copy));
}
return result;
}
protected void doStop() throws Exception {
if (executorService != null) {
executorService.shutdown();
executorService.awaitTermination(0, TimeUnit.SECONDS);
executorService = null;
}
ServiceHelper.stopServices(processors);
}
protected void doStart() throws Exception {
ServiceHelper.startServices(processors);
}
private static void setToEndpoint(Exchange exchange, Processor processor) {
if (processor instanceof Producer) {
Producer producer = (Producer) processor;
exchange.setProperty(Exchange.TO_ENDPOINT, producer.getEndpoint().getEndpointUri());
}
}
/**
* Is the multicast processor working in streaming mode?
*
* In streaming mode:
* <ul>
* <li>we use {@link Iterable} to ensure we can send messages as soon as the data becomes available</li>
* <li>for parallel processing, we start aggregating responses as they get send back to the processor;
* this means the {@link org.apache.camel.processor.aggregate.AggregationStrategy} has to take care of handling out-of-order arrival of exchanges</li>
* </ul>
*/
public boolean isStreaming() {
return streaming;
}
/**
* Should the multicast processor stop processing further exchanges in case of an exception occurred?
*/
public boolean isStopOnException() {
return stopOnException;
}
/**
* Returns the producers to multicast to
*/
public Collection<Processor> getProcessors() {
return processors;
}
public AggregationStrategy getAggregationStrategy() {
return aggregationStrategy;
}
public boolean isParallelProcessing() {
return isParallelProcessing;
}
public ExecutorService getExecutorService() {
return executorService;
}
public void setExecutorService(ExecutorService executorService) {
this.executorService = executorService;
}
public List<Processor> next() {
if (!hasNext()) {
return null;
}
return new ArrayList<Processor>(processors);
}
public boolean hasNext() {
return processors != null && !processors.isEmpty();
}
}