/**
* 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.activemq.transport.mqtt;
import java.io.IOException;
import java.util.Timer;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.activemq.command.KeepAliveInfo;
import org.apache.activemq.thread.SchedulerTimerTask;
import org.apache.activemq.transport.AbstractInactivityMonitor;
import org.apache.activemq.transport.InactivityIOException;
import org.apache.activemq.transport.Transport;
import org.apache.activemq.transport.TransportFilter;
import org.apache.activemq.util.ThreadPoolUtils;
import org.apache.activemq.wireformat.WireFormat;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class MQTTInactivityMonitor extends TransportFilter {
private static final Logger LOG = LoggerFactory.getLogger(MQTTInactivityMonitor.class);
private static ThreadPoolExecutor ASYNC_TASKS;
private static int CHECKER_COUNTER;
private static long DEFAULT_CHECK_TIME_MILLS = 30000;
private static Timer READ_CHECK_TIMER;
private final AtomicBoolean monitorStarted = new AtomicBoolean(false);
private final AtomicBoolean commandSent = new AtomicBoolean(false);
private final AtomicBoolean inSend = new AtomicBoolean(false);
private final AtomicBoolean failed = new AtomicBoolean(false);
private final AtomicBoolean commandReceived = new AtomicBoolean(true);
private final AtomicBoolean inReceive = new AtomicBoolean(false);
private final AtomicInteger lastReceiveCounter = new AtomicInteger(0);
private final ReentrantReadWriteLock sendLock = new ReentrantReadWriteLock();
private SchedulerTimerTask readCheckerTask;
private long readCheckTime = DEFAULT_CHECK_TIME_MILLS;
private long initialDelayTime = DEFAULT_CHECK_TIME_MILLS;
private boolean keepAliveResponseRequired;
private MQTTProtocolConverter protocolConverter;
private final Runnable readChecker = new Runnable() {
long lastRunTime;
public void run() {
long now = System.currentTimeMillis();
long elapsed = (now - lastRunTime);
if (lastRunTime != 0 && LOG.isDebugEnabled()) {
LOG.debug("" + elapsed + " ms elapsed since last read check.");
}
// Perhaps the timer executed a read check late.. and then executes
// the next read check on time which causes the time elapsed between
// read checks to be small..
// If less than 90% of the read check Time elapsed then abort this readcheck.
if (!allowReadCheck(elapsed)) { // FUNKY qdox bug does not allow me to inline this expression.
LOG.debug("Aborting read check.. Not enough time elapsed since last read check.");
return;
}
lastRunTime = now;
readCheck();
}
};
private boolean allowReadCheck(long elapsed) {
return elapsed > (readCheckTime * 9 / 10);
}
public MQTTInactivityMonitor(Transport next, WireFormat wireFormat) {
super(next);
}
public void start() throws Exception {
next.start();
startMonitorThread();
}
public void stop() throws Exception {
stopMonitorThread();
next.stop();
}
final void readCheck() {
int currentCounter = next.getReceiveCounter();
int previousCounter = lastReceiveCounter.getAndSet(currentCounter);
if (inReceive.get() || currentCounter != previousCounter) {
if (LOG.isTraceEnabled()) {
LOG.trace("A receive is in progress");
}
return;
}
if (!commandReceived.get() && monitorStarted.get() && !ASYNC_TASKS.isTerminating()) {
if (LOG.isDebugEnabled()) {
LOG.debug("No message received since last read check for " + toString() + "! Throwing InactivityIOException.");
}
ASYNC_TASKS.execute(new Runnable() {
public void run() {
if (protocolConverter != null) {
protocolConverter.onTransportError();
}
onException(new InactivityIOException("Channel was inactive for too (>" + readCheckTime + ") long: " + next.getRemoteAddress()));
}
;
});
} else {
if (LOG.isTraceEnabled()) {
LOG.trace("Message received since last read check, resetting flag: ");
}
}
commandReceived.set(false);
}
public void onCommand(Object command) {
commandReceived.set(true);
inReceive.set(true);
try {
if (command.getClass() == KeepAliveInfo.class) {
KeepAliveInfo info = (KeepAliveInfo) command;
if (info.isResponseRequired()) {
sendLock.readLock().lock();
try {
info.setResponseRequired(false);
oneway(info);
} catch (IOException e) {
onException(e);
} finally {
sendLock.readLock().unlock();
}
}
} else {
transportListener.onCommand(command);
}
} finally {
inReceive.set(false);
}
}
public void oneway(Object o) throws IOException {
// To prevent the inactivity monitor from sending a message while we
// are performing a send we take a read lock. The inactivity monitor
// sends its Heart-beat commands under a write lock. This means that
// the MutexTransport is still responsible for synchronizing sends
this.sendLock.readLock().lock();
inSend.set(true);
try {
doOnewaySend(o);
} finally {
commandSent.set(true);
inSend.set(false);
this.sendLock.readLock().unlock();
}
}
// Must be called under lock, either read or write on sendLock.
private void doOnewaySend(Object command) throws IOException {
if (failed.get()) {
throw new InactivityIOException("Cannot send, channel has already failed: " + next.getRemoteAddress());
}
next.oneway(command);
}
public void onException(IOException error) {
if (failed.compareAndSet(false, true)) {
stopMonitorThread();
transportListener.onException(error);
}
}
public long getReadCheckTime() {
return readCheckTime;
}
public void setReadCheckTime(long readCheckTime) {
this.readCheckTime = readCheckTime;
}
public long getInitialDelayTime() {
return initialDelayTime;
}
public void setInitialDelayTime(long initialDelayTime) {
this.initialDelayTime = initialDelayTime;
}
public boolean isKeepAliveResponseRequired() {
return this.keepAliveResponseRequired;
}
public void setKeepAliveResponseRequired(boolean value) {
this.keepAliveResponseRequired = value;
}
public boolean isMonitorStarted() {
return this.monitorStarted.get();
}
public void setProtocolConverter(MQTTProtocolConverter protocolConverter) {
this.protocolConverter = protocolConverter;
}
public MQTTProtocolConverter getProtocolConverter() {
return protocolConverter;
}
synchronized void startMonitorThread() {
if (monitorStarted.get()) {
return;
}
if (readCheckTime > 0) {
readCheckerTask = new SchedulerTimerTask(readChecker);
}
if (readCheckTime > 0) {
monitorStarted.set(true);
synchronized (AbstractInactivityMonitor.class) {
if (CHECKER_COUNTER == 0) {
ASYNC_TASKS = createExecutor();
READ_CHECK_TIMER = new Timer("InactivityMonitor ReadCheck", true);
}
CHECKER_COUNTER++;
if (readCheckTime > 0) {
READ_CHECK_TIMER.schedule(readCheckerTask, initialDelayTime, readCheckTime);
}
}
}
}
synchronized void stopMonitorThread() {
if (monitorStarted.compareAndSet(true, false)) {
if (readCheckerTask != null) {
readCheckerTask.cancel();
}
synchronized (AbstractInactivityMonitor.class) {
READ_CHECK_TIMER.purge();
CHECKER_COUNTER--;
if (CHECKER_COUNTER == 0) {
READ_CHECK_TIMER.cancel();
READ_CHECK_TIMER = null;
ThreadPoolUtils.shutdown(ASYNC_TASKS);
ASYNC_TASKS = null;
}
}
}
}
private ThreadFactory factory = new ThreadFactory() {
public Thread newThread(Runnable runnable) {
Thread thread = new Thread(runnable, "MQTTInactivityMonitor Async Task: " + runnable);
thread.setDaemon(true);
return thread;
}
};
private ThreadPoolExecutor createExecutor() {
ThreadPoolExecutor exec = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 10, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(), factory);
exec.allowCoreThreadTimeOut(true);
return exec;
}
}