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package com.sun.appserv.management.util.jmx;
import java.util.List;
import java.util.Map;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Collections;
import javax.management.NotificationBroadcasterSupport;
import javax.management.NotificationListener;
import javax.management.NotificationFilter;
import javax.management.relation.MBeanServerNotificationFilter;
import javax.management.AttributeChangeNotificationFilter;
import javax.management.NotificationFilterSupport;
import javax.management.Notification;
import javax.management.AttributeChangeNotification;
import javax.management.MBeanServerNotification;
import javax.management.ListenerNotFoundException;
import com.sun.appserv.management.util.misc.ListUtil;
/**
Features:
<ul>
<li>Maintains information on all NotificationListeners so that queries can
be made on the number of listeners, and the number of listeners of each type</li>
<li>optionally sends all Notifications asynchronously via a separate Thread</li>
</ul>
*/
public class NotificationEmitterSupport
extends NotificationBroadcasterSupport
{
private final boolean mAsyncDelivery;
private SenderThread mSenderThread;
private final Map<String,Integer> mListenerTypeCounts;
private final NotificationListenerTracking mListeners;
public
NotificationEmitterSupport(
final boolean asyncDelivery)
{
mAsyncDelivery = asyncDelivery;
// don't create a thread until needed
mSenderThread = null;
mListenerTypeCounts = Collections.synchronizedMap( new HashMap<String,Integer>() );
mListeners = new NotificationListenerTracking( true );
}
private synchronized SenderThread
getSenderThread()
{
if ( mSenderThread == null )
{
mSenderThread = mAsyncDelivery ? new SenderThread() : null;
if ( mSenderThread != null )
{
mSenderThread.start();
}
}
return( mSenderThread );
}
public synchronized void
cleanup()
{
if ( mSenderThread != null )
{
mSenderThread.quit();
mSenderThread = null;
}
}
/**
Synchronously (on current thread), ensure that all Notifications
have been delivered.
*/
public void
sendAll( )
{
if ( mSenderThread != null )
{
mSenderThread.sendAll();
}
}
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 = new Integer( 1 );
private void
incrementListenerCountForType( final String type )
{
synchronized( mListenerTypeCounts )
{
final Integer count = mListenerTypeCounts.get( type );
final Integer newCount = (count == null ) ?
COUNT_1 : new Integer( 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, new Integer( oldValue - 1 ) );
}
}
}
private String[]
getTypes(
final NotificationFilter filter )
{
String[] types = NO_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<NotificationListenerInfo> infos )
{
for( NotificationListenerInfo info : infos )
{
removeFilterTypeCounts( info.getFilter() );
}
}
public void
addNotificationListener(
final NotificationListener listener,
final NotificationFilter filter,
final Object handback)
{
super.addNotificationListener( listener, filter, handback );
mListeners.addNotificationListener( listener, filter, handback );
addFilterTypeCounts( filter );
}
public void
removeNotificationListener(final NotificationListener listener)
throws ListenerNotFoundException
{
super.removeNotificationListener( listener );
final List<NotificationListenerInfo> infos =
mListeners.removeNotificationListener( listener );
removeFilterTypeCounts( infos );
}
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.
*/
public void
sendNotification( final Notification notif )
{
if ( getListenerCount() != 0 )
{
if ( getSenderThread() != null )
{
mSenderThread.enqueue( notif );
}
else
{
internalSendNotification( notif );
}
}
}
private final class SenderThread extends Thread
{
private boolean mQuit;
private List<Notification> mPendingNotifications;
public
SenderThread()
{
mQuit = false;
mPendingNotifications =
Collections.synchronizedList( new LinkedList<Notification>() );
}
public void
quit()
{
mQuit = true;
notifySelf();
}
private void
notifySelf()
{
synchronized( this )
{
this.notify();
}
}
private void
enqueue( final Notification notif )
{
mPendingNotifications.add( notif );
notifySelf();
}
public boolean
sendAll()
{
Notification notif = null;
boolean sentSomething = false;
while ( ! mPendingNotifications.isEmpty() )
{
sentSomething = true; // or rather, we'll try to
try
{
notif = mPendingNotifications.remove( 0 );
internalSendNotification( notif );
}
catch( ArrayIndexOutOfBoundsException e )
{
// can happen if more than one Thread is in here
}
}
return( sentSomething );
}
public void
run()
{
// wake up every 5 minutes
final int INTERVAL = 5 * 1000;
mQuit = false;
while ( ! mQuit )
{
try
{
synchronized( this )
{
wait( INTERVAL );
}
}
catch( InterruptedException e )
{
}
if ( mQuit )
{
break;
}
final boolean sentSomething = sendAll();
// nothing available, get rid of ourself till needed
if ( ! sentSomething )
{
cleanup();
// now no new ones can be added, but ensure any pending are sent
sendAll();
break;
}
}
}
}
}
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