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package org.glassfish.admin.amx.util.jmx;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.management.AttributeChangeNotification;
import javax.management.AttributeChangeNotificationFilter;
import javax.management.ListenerNotFoundException;
import javax.management.MBeanServerNotification;
import javax.management.Notification;
import javax.management.NotificationBroadcasterSupport;
import javax.management.NotificationFilter;
import javax.management.NotificationFilterSupport;
import javax.management.NotificationListener;
import javax.management.relation.MBeanServerNotificationFilter;
import org.glassfish.admin.amx.util.ListUtil;
/**
Features:
- Maintains information on all NotificationListeners so that queries can
be made on the number of listeners, and the number of listeners of each type
- optionally sends all Notifications asynchronously via a separate Thread
For async use, a shared sender thread is used for all Notifications.
*/
public final class NotificationEmitterSupport
extends NotificationBroadcasterSupport
{
private final boolean mAsyncDelivery;
private static volatile SenderThread sSenderThread = null;
private final Map mListenerTypeCounts;
private final NotificationListenerTracking mListeners;
public NotificationEmitterSupport(
final boolean asyncDelivery)
{
mAsyncDelivery = asyncDelivery;
mListenerTypeCounts = Collections.synchronizedMap(new HashMap());
mListeners = new NotificationListenerTracking(true);
}
public void cleanup()
{
// NO-OP with the shared SenderThread
/*
if ( mSenderThread != null )
{
mSenderThread.quit();
mSenderThread = null;
}
*/
}
/**
Synchronously (on current thread), ensure that all Notifications
have been delivered.
*/
public void sendAll()
{
// they will all be sent as fast as the sender thread can go, but the caller wants
// them all sent before return
if (sSenderThread != null)
{
sSenderThread.waitSentAll(this);
}
}
public int getListenerCount()
{
return (mListeners.getListenerCount());
}
public int getNotificationTypeListenerCount(final String type)
{
final Integer count = mListenerTypeCounts.get(type);
int resultCount = 0;
if (count == null)
{
final Integer allCount = mListenerTypeCounts.get(WILDCARD_TYPE);
if (allCount != null)
{
resultCount = allCount;
}
else
{
// no wildcards are in use
}
}
return (resultCount);
}
private static final String[] NO_TYPES = new String[0];
private static final String WILDCARD_TYPE = "***";
private static final String[] ALL_TYPES = new String[]
{
WILDCARD_TYPE
};
private static final String[] ATTRIBUTE_CHANGE_TYPES = new String[]
{
AttributeChangeNotification.ATTRIBUTE_CHANGE
};
private static final String[] MBEAN_SERVER_NOTIFICATION_TYPES = new String[]
{
MBeanServerNotification.REGISTRATION_NOTIFICATION,
MBeanServerNotification.UNREGISTRATION_NOTIFICATION,
};
private final Integer COUNT_1 = Integer.valueOf(1);
private void incrementListenerCountForType(final String type)
{
synchronized (mListenerTypeCounts)
{
final Integer count = mListenerTypeCounts.get(type);
final Integer newCount = (count == null) ? COUNT_1 : Integer.valueOf(count.intValue() + 1);
mListenerTypeCounts.put(type, newCount);
}
}
private void decrementListenerCountForType(final String type)
{
synchronized (mListenerTypeCounts)
{
final Integer count = mListenerTypeCounts.get(type);
if (count == null)
{
throw new IllegalArgumentException(type);
}
final int oldValue = count.intValue();
if (oldValue == 1)
{
mListenerTypeCounts.remove(type);
}
else
{
mListenerTypeCounts.put(type, Integer.valueOf(oldValue - 1));
}
}
}
private String[] getTypes(
final NotificationFilter filter)
{
String[] types;
if (filter instanceof NotificationFilterSupport)
{
final NotificationFilterSupport fs = (NotificationFilterSupport) filter;
types = ListUtil.toStringArray(fs.getEnabledTypes());
}
else if (filter instanceof AttributeChangeNotificationFilter)
{
types = ATTRIBUTE_CHANGE_TYPES;
}
else if (filter instanceof MBeanServerNotificationFilter)
{
types = MBEAN_SERVER_NOTIFICATION_TYPES;
}
else
{
// no filter, or non-standard one, have to assume all types
types = ALL_TYPES;
}
return types;
}
private void addFilterTypeCounts(final NotificationFilter filter)
{
String[] types = getTypes(filter);
for (String type : types)
{
incrementListenerCountForType(type);
}
}
private void removeFilterTypeCounts(final NotificationFilter filter)
{
final String[] types = getTypes(filter);
for (String type : types)
{
decrementListenerCountForType(type);
}
}
private void removeFilterTypeCounts(final List infos)
{
for (NotificationListenerInfo info : infos)
{
removeFilterTypeCounts(info.getFilter());
}
}
@Override
public void addNotificationListener(
final NotificationListener listener,
final NotificationFilter filter,
final Object handback)
{
super.addNotificationListener(listener, filter, handback);
mListeners.addNotificationListener(listener, filter, handback);
addFilterTypeCounts(filter);
}
@Override
public void removeNotificationListener(final NotificationListener listener)
throws ListenerNotFoundException
{
super.removeNotificationListener(listener);
final List infos =
mListeners.removeNotificationListener(listener);
removeFilterTypeCounts(infos);
}
@Override
public void removeNotificationListener(
final NotificationListener listener,
final NotificationFilter filter,
final Object handback)
throws ListenerNotFoundException
{
super.removeNotificationListener(listener, filter, handback);
mListeners.removeNotificationListener(listener);
if (filter != null)
{
removeFilterTypeCounts(filter);
}
}
protected void internalSendNotification(final Notification notif)
{
super.sendNotification(notif);
}
/**
Send the Notification. If created with async=true,
then this routine returns immediately and the Notification is sent
on a separate Thread.
*/
@Override
public synchronized void sendNotification(final Notification notif)
{
if (getListenerCount() != 0)
{
final SenderThread senderThread = getSenderThread(mAsyncDelivery);
if (senderThread != null)
{
senderThread.enqueue(notif, this);
}
else
{
internalSendNotification(notif);
}
}
}
private static final Object senderThreadLock = new Object();
private static SenderThread getSenderThread(final boolean asyncDelivery)
{
// sSenderThread MUST be 'volatile' for this to be thread-safe
if (sSenderThread != null)
{
return sSenderThread;
}
synchronized (senderThreadLock)
{
if (sSenderThread == null)
{
sSenderThread = asyncDelivery ? new SenderThread() : null;
if (sSenderThread != null)
{
sSenderThread.start();
}
}
}
return (sSenderThread);
}
private static final class SenderThread extends Thread
{
private volatile boolean mQuit;
private final LinkedBlockingQueue mPendingNotifications;
private static final class QueueItem
{
private final Notification mNotif;
private final NotificationEmitterSupport mSender;
public QueueItem(final Notification notif, final NotificationEmitterSupport sender)
{
mNotif = notif;
mSender = sender;
}
}
public SenderThread()
{
setDaemon(true);
mQuit = false;
mPendingNotifications = new LinkedBlockingQueue();
}
public void quit()
{
mQuit = true;
this.interrupt();
}
private void enqueue(
final Notification notif,
final NotificationEmitterSupport sender)
{
mPendingNotifications.add(new QueueItem(notif, sender));
}
/**
A fake Notification to used for waitSentAll()
*/
static final class CountDownLatchNofication extends Notification
{
private static final long serialVersionUID = 0xDEADBEEF; // never serialized
final transient CountDownLatch mLatch = new CountDownLatch(1);
CountDownLatchNofication(final Object source)
{
super("CountDownLatchNofication", source, 0);
}
}
/**
Ensure that all existing items have been sent.
Check the queue for empty does not work; we need to see that thread has
not only emptied the queue, but grabbed the next item.
*/
public void waitSentAll(final NotificationEmitterSupport sender)
{
final CountDownLatchNofication notif = new CountDownLatchNofication(this);
enqueue(notif, sender);
try
{
notif.mLatch.await();
}
catch (InterruptedException e)
{
Logger.getAnonymousLogger().log(Level.WARNING, "Interrupted: ", e);
}
}
@Override
public void run()
{
while (!mQuit)
{
try
{
final QueueItem item = mPendingNotifications.take();
final Notification notif = item.mNotif;
if (notif instanceof CountDownLatchNofication)
{
// internal mechanism, see waitEmpty()
((CountDownLatchNofication) notif).mLatch.countDown();
}
else
{
item.mSender.internalSendNotification(notif);
}
}
catch (InterruptedException e)
{
// what does this mean if interrupted other than by quit() ?
// Presumably we're supposed to stop working
mQuit = true;
}
}
}
}
}