/**
* 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;
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 org.apache.activemq.command.KeepAliveInfo;
import org.apache.activemq.command.WireFormatInfo;
import org.apache.activemq.thread.SchedulerTimerTask;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Used to make sure that commands are arriving periodically from the peer of
* the transport.
*
* @version $Revision$
*/
public class InactivityMonitor extends TransportFilter {
private static final Log LOG = LogFactory.getLog(InactivityMonitor.class);
private static final ThreadPoolExecutor ASYNC_TASKS;
private static int CHECKER_COUNTER;
private static Timer READ_CHECK_TIMER;
private static Timer WRITE_CHECK_TIMER;
private WireFormatInfo localWireFormatInfo;
private WireFormatInfo remoteWireFormatInfo;
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 SchedulerTimerTask writeCheckerTask;
private SchedulerTimerTask readCheckerTask;
private long readCheckTime;
private long writeCheckTime;
private long initialDelayTime;
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);
}
private final Runnable writeChecker = new Runnable() {
long lastRunTime;
public void run() {
long now = System.currentTimeMillis();
if( lastRunTime != 0 && LOG.isDebugEnabled() ) {
LOG.debug(""+(now-lastRunTime)+" ms elapsed since last write check.");
}
lastRunTime = now;
writeCheck();
}
};
public InactivityMonitor(Transport next) {
super(next);
}
public void stop() throws Exception {
stopMonitorThreads();
next.stop();
}
final void writeCheck() {
if (inSend.get()) {
if (LOG.isTraceEnabled()) {
LOG.trace("A send is in progress");
}
return;
}
if (!commandSent.get()) {
if(LOG.isTraceEnabled()) {
LOG.trace("No message sent since last write check, sending a KeepAliveInfo");
}
ASYNC_TASKS.execute(new Runnable() {
public void run() {
if (monitorStarted.get()) {
try {
KeepAliveInfo info = new KeepAliveInfo();
info.setResponseRequired(true);
oneway(info);
} catch (IOException e) {
onException(e);
}
}
};
});
} else {
if (LOG.isTraceEnabled()) {
LOG.trace("Message sent since last write check, resetting flag");
}
}
commandSent.set(false);
}
final void readCheck() {
if (inReceive.get()) {
if (LOG.isTraceEnabled()) {
LOG.trace("A receive is in progress");
}
return;
}
if (!commandReceived.get()) {
if (LOG.isDebugEnabled()) {
LOG.debug("No message received since last read check for " + toString() + "! Throwing InactivityIOException.");
}
ASYNC_TASKS.execute(new Runnable() {
public void run() {
onException(new InactivityIOException("Channel was inactive for too 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()) {
try {
info.setResponseRequired(false);
oneway(info);
} catch (IOException e) {
onException(e);
}
}
} else {
if (command.getClass() == WireFormatInfo.class) {
synchronized (this) {
IOException error = null;
remoteWireFormatInfo = (WireFormatInfo) command;
try {
startMonitorThreads();
} catch (IOException e) {
error = e;
}
if (error != null) {
onException(error);
}
}
}
synchronized (readChecker) {
transportListener.onCommand(command);
}
}
} finally {
inReceive.set(false);
}
}
public void oneway(Object o) throws IOException {
// Disable inactivity monitoring while processing a command.
//synchronize this method - its not synchronized
//further down the transport stack and gets called by more
//than one thread by this class
synchronized(inSend) {
inSend.set(true);
try {
if( failed.get() ) {
throw new InactivityIOException("Channel was inactive for too long: "+next.getRemoteAddress());
}
if (o.getClass() == WireFormatInfo.class) {
synchronized (this) {
localWireFormatInfo = (WireFormatInfo)o;
startMonitorThreads();
}
}
next.oneway(o);
} finally {
commandSent.set(true);
inSend.set(false);
}
}
}
public void onException(IOException error) {
if (failed.compareAndSet(false, true)) {
stopMonitorThreads();
transportListener.onException(error);
}
}
private synchronized void startMonitorThreads() throws IOException {
if (monitorStarted.get()) {
return;
}
if (localWireFormatInfo == null) {
return;
}
if (remoteWireFormatInfo == null) {
return;
}
readCheckTime = Math.min(localWireFormatInfo.getMaxInactivityDuration(), remoteWireFormatInfo.getMaxInactivityDuration());
initialDelayTime = Math.min(localWireFormatInfo.getMaxInactivityDurationInitalDelay(), remoteWireFormatInfo.getMaxInactivityDurationInitalDelay());
if (readCheckTime > 0) {
monitorStarted.set(true);
writeCheckerTask = new SchedulerTimerTask(writeChecker);
readCheckerTask = new SchedulerTimerTask(readChecker);
writeCheckTime = readCheckTime/3;
synchronized( InactivityMonitor.class ) {
if( CHECKER_COUNTER == 0 ) {
READ_CHECK_TIMER = new Timer("InactivityMonitor ReadCheck",true);
WRITE_CHECK_TIMER = new Timer("InactivityMonitor WriteCheck",true);
}
CHECKER_COUNTER++;
WRITE_CHECK_TIMER.scheduleAtFixedRate(writeCheckerTask, initialDelayTime,writeCheckTime);
READ_CHECK_TIMER.scheduleAtFixedRate(readCheckerTask, initialDelayTime,readCheckTime);
}
}
}
/**
*
*/
private synchronized void stopMonitorThreads() {
if (monitorStarted.compareAndSet(true, false)) {
readCheckerTask.cancel();
writeCheckerTask.cancel();
synchronized( InactivityMonitor.class ) {
WRITE_CHECK_TIMER.purge();
READ_CHECK_TIMER.purge();
CHECKER_COUNTER--;
if(CHECKER_COUNTER==0) {
WRITE_CHECK_TIMER.cancel();
READ_CHECK_TIMER.cancel();
WRITE_CHECK_TIMER = null;
READ_CHECK_TIMER = null;
}
}
}
}
static {
ASYNC_TASKS = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 10, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(), new ThreadFactory() {
public Thread newThread(Runnable runnable) {
Thread thread = new Thread(runnable, "InactivityMonitor Async Task: "+runnable);
thread.setDaemon(true);
return thread;
}
});
}
}