/**
* 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.concurrent.RejectedExecutionException;
import org.apache.camel.AsyncCallback;
import org.apache.camel.AsyncProcessor;
import org.apache.camel.Exchange;
import org.apache.camel.Message;
import org.apache.camel.Processor;
import org.apache.camel.impl.converter.AsyncProcessorTypeConverter;
import org.apache.camel.model.ExceptionType;
import org.apache.camel.util.AsyncProcessorHelper;
import org.apache.camel.util.ServiceHelper;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Implements a <a
* href="http://activemq.apache.org/camel/dead-letter-channel.html">Dead Letter
* Channel</a> after attempting to redeliver the message using the
* {@link RedeliveryPolicy}
*
* @version $Revision: 640438 $
*/
public class DeadLetterChannel extends ErrorHandlerSupport implements AsyncProcessor {
public static final String REDELIVERY_COUNTER = "org.apache.camel.RedeliveryCounter";
public static final String REDELIVERED = "org.apache.camel.Redelivered";
public static final String EXCEPTION_CAUSE_PROPERTY = "CamelCauseException";
private class RedeliveryData {
int redeliveryCounter;
long redeliveryDelay;
boolean sync = true;
// default behaviour which can be overloaded on a per exception basis
RedeliveryPolicy currentRedeliveryPolicy = redeliveryPolicy;
Processor failureProcessor = deadLetter;
}
private static final transient Log LOG = LogFactory.getLog(DeadLetterChannel.class);
private static final String FAILURE_HANDLED_PROPERTY = DeadLetterChannel.class.getName() + ".FAILURE_HANDLED";
private Processor output;
private Processor deadLetter;
private AsyncProcessor outputAsync;
private RedeliveryPolicy redeliveryPolicy;
private Logger logger;
public DeadLetterChannel(Processor output, Processor deadLetter) {
this(output, deadLetter, new RedeliveryPolicy(), DeadLetterChannel.createDefaultLogger());
}
public DeadLetterChannel(Processor output, Processor deadLetter, RedeliveryPolicy redeliveryPolicy, Logger logger) {
this.deadLetter = deadLetter;
this.output = output;
this.outputAsync = AsyncProcessorTypeConverter.convert(output);
this.redeliveryPolicy = redeliveryPolicy;
this.logger = logger;
}
public static <E extends Exchange> Logger createDefaultLogger() {
return new Logger(LOG, LoggingLevel.ERROR);
}
@Override
public String toString() {
return "DeadLetterChannel[" + output + ", " + deadLetter + ", " + redeliveryPolicy + "]";
}
public boolean process(Exchange exchange, final AsyncCallback callback) {
return process(exchange, callback, new RedeliveryData());
}
public boolean process(final Exchange exchange, final AsyncCallback callback, final RedeliveryData data) {
while (true) {
// We can't keep retrying if the route is being shutdown.
if (!isRunAllowed()) {
if (exchange.getException() == null) {
exchange.setException(new RejectedExecutionException());
}
callback.done(data.sync);
return data.sync;
}
if (exchange.getException() != null) {
Throwable e = exchange.getException();
exchange.setException(null); // Reset it since we are handling it.
logger.log("Failed delivery for exchangeId: " + exchange.getExchangeId() + ". On delivery attempt: " + data.redeliveryCounter + " caught: " + e, e);
data.redeliveryCounter = incrementRedeliveryCounter(exchange, e);
ExceptionType exceptionPolicy = getExceptionPolicy(exchange, e);
if (exceptionPolicy != null) {
data.currentRedeliveryPolicy = exceptionPolicy.createRedeliveryPolicy(data.currentRedeliveryPolicy);
Processor processor = exceptionPolicy.getErrorHandler();
if (processor != null) {
data.failureProcessor = processor;
}
}
}
if (!data.currentRedeliveryPolicy.shouldRedeliver(data.redeliveryCounter)) {
setFailureHandled(exchange, true);
AsyncProcessor afp = AsyncProcessorTypeConverter.convert(data.failureProcessor);
boolean sync = afp.process(exchange, new AsyncCallback() {
public void done(boolean sync) {
restoreExceptionOnExchange(exchange);
callback.done(data.sync);
}
});
restoreExceptionOnExchange(exchange);
logger.log("Failed delivery for exchangeId: " + exchange.getExchangeId() + ". Handled by the failure processor: " + data.failureProcessor);
return sync;
}
if (data.redeliveryCounter > 0) {
// Figure out how long we should wait to resend this message.
data.redeliveryDelay = data.currentRedeliveryPolicy.getRedeliveryDelay(data.redeliveryDelay);
sleep(data.redeliveryDelay);
}
exchange.setProperty(EXCEPTION_CAUSE_PROPERTY, exchange.getException());
exchange.setException(null);
boolean sync = outputAsync.process(exchange, new AsyncCallback() {
public void done(boolean sync) {
// Only handle the async case...
if (sync) {
return;
}
data.sync = false;
if (exchange.getException() != null) {
process(exchange, callback, data);
} else {
callback.done(sync);
}
}
});
if (!sync) {
// It is going to be processed async..
return false;
}
if (exchange.getException() == null || isFailureHandled(exchange)) {
// If everything went well.. then we exit here..
callback.done(true);
return true;
}
// error occured so loop back around.....
}
}
public static boolean isFailureHandled(Exchange exchange) {
return exchange.getProperty(FAILURE_HANDLED_PROPERTY) != null;
}
public static void setFailureHandled(Exchange exchange, boolean isHandled) {
if (isHandled) {
exchange.setProperty(FAILURE_HANDLED_PROPERTY, exchange.getException());
exchange.setException(null);
} else {
exchange.setException(exchange.getProperty(FAILURE_HANDLED_PROPERTY, Throwable.class));
exchange.removeProperty(FAILURE_HANDLED_PROPERTY);
}
}
public static void restoreExceptionOnExchange(Exchange exchange) {
exchange.setException(exchange.getProperty(FAILURE_HANDLED_PROPERTY, Throwable.class));
}
public void process(Exchange exchange) throws Exception {
AsyncProcessorHelper.process(this, exchange);
}
// Properties
// -------------------------------------------------------------------------
/**
* Returns the output processor
*/
public Processor getOutput() {
return output;
}
/**
* Returns the dead letter that message exchanges will be sent to if the
* redelivery attempts fail
*/
public Processor getDeadLetter() {
return deadLetter;
}
public RedeliveryPolicy getRedeliveryPolicy() {
return redeliveryPolicy;
}
/**
* Sets the redelivery policy
*/
public void setRedeliveryPolicy(RedeliveryPolicy redeliveryPolicy) {
this.redeliveryPolicy = redeliveryPolicy;
}
public Logger getLogger() {
return logger;
}
/**
* Sets the logger strategy; which {@link Log} to use and which
* {@link LoggingLevel} to use
*/
public void setLogger(Logger logger) {
this.logger = logger;
}
// Implementation methods
// -------------------------------------------------------------------------
/**
* Increments the redelivery counter and adds the redelivered flag if the
* message has been redelivered
*/
protected int incrementRedeliveryCounter(Exchange exchange, Throwable e) {
Message in = exchange.getIn();
Integer counter = in.getHeader(REDELIVERY_COUNTER, Integer.class);
int next = 1;
if (counter != null) {
next = counter + 1;
}
in.setHeader(REDELIVERY_COUNTER, next);
in.setHeader(REDELIVERED, true);
exchange.setException(e);
return next;
}
protected void sleep(long redeliveryDelay) {
if (redeliveryDelay > 0) {
if (LOG.isDebugEnabled()) {
LOG.debug("Sleeping for: " + redeliveryDelay + " millis until attempting redelivery");
}
try {
Thread.sleep(redeliveryDelay);
} catch (InterruptedException e) {
if (LOG.isDebugEnabled()) {
LOG.debug("Thread interupted: " + e, e);
}
}
}
}
protected void doStart() throws Exception {
ServiceHelper.startServices(output, deadLetter);
}
protected void doStop() throws Exception {
ServiceHelper.stopServices(deadLetter, output);
}
}