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The Core Camel Java DSL based router
/**
* 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 java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.camel.AsyncCallback;
import org.apache.camel.CamelContext;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.util.ObjectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A useful base class for any processor which provides some kind of throttling
* or delayed processing.
*
* This implementation will block while waiting.
*
* @version
*/
public abstract class DelayProcessorSupport extends DelegateAsyncProcessor {
protected final Logger log = LoggerFactory.getLogger(getClass());
private final CamelContext camelContext;
private final ScheduledExecutorService executorService;
private final boolean shutdownExecutorService;
private boolean asyncDelayed;
private boolean callerRunsWhenRejected = true;
private final AtomicInteger delayedCount = new AtomicInteger(0);
// TODO: Add option to cancel tasks on shutdown so we can stop fast
private final class ProcessCall implements Runnable {
private final Exchange exchange;
private final AsyncCallback callback;
ProcessCall(Exchange exchange, AsyncCallback callback) {
this.exchange = exchange;
this.callback = callback;
}
public void run() {
// we are running now so decrement the counter
delayedCount.decrementAndGet();
log.trace("Delayed task woke up and continues routing for exchangeId: {}", exchange.getExchangeId());
if (!isRunAllowed()) {
exchange.setException(new RejectedExecutionException("Run is not allowed"));
}
// process the exchange now that we woke up
DelayProcessorSupport.this.processor.process(exchange, new AsyncCallback() {
@Override
public void done(boolean doneSync) {
log.trace("Delayed task done for exchangeId: {}", exchange.getExchangeId());
// we must done the callback from this async callback as well, to ensure callback is done correctly
// must invoke done on callback with false, as that is what the original caller would
// expect as we returned false in the process method
callback.done(false);
}
});
}
}
public DelayProcessorSupport(CamelContext camelContext, Processor processor) {
this(camelContext, processor, null, false);
}
public DelayProcessorSupport(CamelContext camelContext, Processor processor, ScheduledExecutorService executorService, boolean shutdownExecutorService) {
super(processor);
this.camelContext = camelContext;
this.executorService = executorService;
this.shutdownExecutorService = shutdownExecutorService;
}
protected boolean processDelay(Exchange exchange, AsyncCallback callback, long delay) {
if (!isAsyncDelayed() || exchange.isTransacted()) {
// use synchronous delay (also required if using transactions)
try {
delay(delay, exchange);
// then continue routing
return processor.process(exchange, callback);
} catch (Exception e) {
// exception occurred so we are done
exchange.setException(e);
callback.done(true);
return true;
}
} else {
// asynchronous delay so schedule a process call task
// and increment the counter (we decrement the counter when we run the ProcessCall)
delayedCount.incrementAndGet();
ProcessCall call = new ProcessCall(exchange, callback);
try {
log.trace("Scheduling delayed task to run in {} millis for exchangeId: {}",
delay, exchange.getExchangeId());
executorService.schedule(call, delay, TimeUnit.MILLISECONDS);
// tell Camel routing engine we continue routing asynchronous
return false;
} catch (RejectedExecutionException e) {
// we were not allowed to run the ProcessCall, so need to decrement the counter here
delayedCount.decrementAndGet();
if (isCallerRunsWhenRejected()) {
if (!isRunAllowed()) {
exchange.setException(new RejectedExecutionException());
} else {
log.debug("Scheduling rejected task, so letting caller run, delaying at first for {} millis for exchangeId: {}", delay, exchange.getExchangeId());
// let caller run by processing
try {
delay(delay, exchange);
} catch (InterruptedException ie) {
exchange.setException(ie);
}
// then continue routing
return processor.process(exchange, callback);
}
} else {
exchange.setException(e);
}
// caller don't run the task so we are done
callback.done(true);
return true;
}
}
}
@Override
public boolean process(Exchange exchange, AsyncCallback callback) {
if (!isRunAllowed()) {
exchange.setException(new RejectedExecutionException("Run is not allowed"));
callback.done(true);
return true;
}
// calculate delay and wait
long delay;
try {
delay = calculateDelay(exchange);
if (delay <= 0) {
// no delay then continue routing
log.trace("No delay for exchangeId: {}", exchange.getExchangeId());
return processor.process(exchange, callback);
}
} catch (Throwable e) {
exchange.setException(e);
callback.done(true);
return true;
}
return processDelay(exchange, callback, delay);
}
public boolean isAsyncDelayed() {
return asyncDelayed;
}
public void setAsyncDelayed(boolean asyncDelayed) {
this.asyncDelayed = asyncDelayed;
}
public boolean isCallerRunsWhenRejected() {
return callerRunsWhenRejected;
}
public void setCallerRunsWhenRejected(boolean callerRunsWhenRejected) {
this.callerRunsWhenRejected = callerRunsWhenRejected;
}
protected abstract long calculateDelay(Exchange exchange);
/**
* Gets the current number of {@link Exchange}s being delayed (hold back due throttle limit hit)
*/
public int getDelayedCount() {
return delayedCount.get();
}
/**
* Delays the given time before continuing.
*
* This implementation will block while waiting
*
* @param delay the delay time in millis
* @param exchange the exchange being processed
*/
protected void delay(long delay, Exchange exchange) throws InterruptedException {
// only run is we are started
if (!isRunAllowed()) {
return;
}
if (delay < 0) {
return;
} else {
try {
// keep track on delayer counter while we sleep
delayedCount.incrementAndGet();
sleep(delay);
} catch (InterruptedException e) {
handleSleepInterruptedException(e, exchange);
} finally {
delayedCount.decrementAndGet();
}
}
}
/**
* Called when a sleep is interrupted; allows derived classes to handle this case differently
*/
protected void handleSleepInterruptedException(InterruptedException e, Exchange exchange) throws InterruptedException {
if (log.isDebugEnabled()) {
log.debug("Sleep interrupted, are we stopping? {}", isStopping() || isStopped());
}
Thread.currentThread().interrupt();
throw e;
}
protected long currentSystemTime() {
return System.currentTimeMillis();
}
private void sleep(long delay) throws InterruptedException {
if (delay <= 0) {
return;
}
log.trace("Sleeping for: {} millis", delay);
Thread.sleep(delay);
}
@Override
protected void doStart() throws Exception {
if (isAsyncDelayed()) {
ObjectHelper.notNull(executorService, "executorService", this);
}
super.doStart();
}
@Override
protected void doShutdown() throws Exception {
if (shutdownExecutorService && executorService != null) {
camelContext.getExecutorServiceManager().shutdownNow(executorService);
}
super.doShutdown();
}
}