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package com.sun.appserv.management.util.jmx;
import java.util.Set;
import java.util.HashSet;
import java.util.Collections;
import java.io.IOException;
import javax.management.ObjectName;
import javax.management.Notification;
import javax.management.NotificationListener;
import javax.management.NotificationFilter;
import javax.management.MBeanServerNotification;
import javax.management.MBeanServer;
import javax.management.MBeanServerConnection;
import javax.management.InstanceNotFoundException;
import javax.management.JMException;
import com.sun.appserv.management.util.misc.GSetUtil;
/**
Convenience base class for listening for Notifications
from one or more MBeans, which may be specified as
a specific MBean ObjectName, or an ObjectName pattern.
If the ObjectName is a pattern, the list of listenees
is dynamically maintained.
<p>
Caller should call {@link #cleanup} when done, because
a listener is maintained on the MBeanServer delegate.
*/
public abstract class NotificationListenerBase
implements NotificationListener
{
private final String mName;
private final MBeanServerConnection mConn;
/** actual MBean ObjectNames, not patterns */
private final Set<ObjectName> mListenees;
/** targets as specified by caller, may be a pattern or fixed ObjectName */
private final ObjectName mPattern;
private final NotificationFilter mFilter;
private final Object mHandback;
private RegistrationListener mDelegateListener;
private volatile boolean mSetupListening;
/**
Calls this( conn, listenTo, null, null ).
<p><b>Instantiating code must call setupListening() in order to initiate
listening</b>
*/
protected
NotificationListenerBase(
final String name,
final MBeanServerConnection conn,
final ObjectName pattern )
throws InstanceNotFoundException, IOException
{
this( name, conn, pattern, null );
}
/**
Listen to all MBean(s) which match the pattern 'listenTo'.
<p><b>Instantiating code must call setupListening() in order to initiate
listening</b>
@param listenerName arbitrary name of this listener
@param conn the MBeanServerConnection or MBeanServer
@param pattern an MBean ObjectName, or an ObjectName pattern
@param filter optional NotificationFilter
*/
protected
NotificationListenerBase(
final String name,
final MBeanServerConnection conn,
final ObjectName pattern,
final NotificationFilter filter )
throws InstanceNotFoundException, IOException
{
mName = name;
mConn = conn;
mPattern = pattern;
mFilter = filter;
mHandback = null;
mDelegateListener = null;
mSetupListening = false;
mListenees = Collections.synchronizedSet( new HashSet<ObjectName>() );
// test connection for validity
if ( ! conn.isRegistered( JMXUtil.getMBeanServerDelegateObjectName() ) )
{
throw new IllegalArgumentException();
}
}
/**
Subclass should implement this routine.
*/
public abstract void
handleNotification( final Notification notif, final Object handback);
protected synchronized void
listenToMBean( final ObjectName objectName )
throws InstanceNotFoundException, IOException
{
if ( ! mListenees.contains( objectName ) )
{
mListenees.add( objectName );
getMBeanServerConnection().addNotificationListener(
objectName, this, mFilter, null );
}
}
public synchronized void
startListening()
throws InstanceNotFoundException, IOException
{
if ( mSetupListening )
{
throw new IllegalStateException( "setupListening() must be called exactly once" );
}
if ( mPattern.isPattern() )
{
// it's crucial we listen for registration/unregistration events
// so that any patterns are maintained.
// do this BEFORE the code below, of we could
// miss a registration.
mDelegateListener = new RegistrationListener();
JMXUtil.listenToMBeanServerDelegate( mConn,
mDelegateListener, null, null );
}
Set<ObjectName> s = null;
if ( mPattern.isPattern() )
{
s = JMXUtil.queryNames( getConn(), mPattern, null );
}
else
{
s = GSetUtil.newSet( mPattern );
}
synchronized( this )
{
for( final ObjectName objectName : s )
{
listenToMBean( objectName );
}
}
mSetupListening = true;
}
/**
Get the filter originally specified when constructing this object.
*/
public final NotificationFilter
getNotificationFilter( final ObjectName objectName)
{
return mFilter;
}
protected synchronized void
listenToIfMatch( final ObjectName objectName )
throws IOException, InstanceNotFoundException
{
if ( ! mListenees.contains( objectName ) )
{
final String defaultDomain = getConn().getDefaultDomain();
if ( JMXUtil.matchesPattern( defaultDomain, mPattern, objectName ) )
{
listenToMBean( objectName );
}
}
}
/**
tracks coming and going of MBeans being listened to which
match our patterns.
*/
private final class RegistrationListener implements NotificationListener
{
public RegistrationListener() {}
public void
handleNotification(
final Notification notifIn,
final Object handback)
{
if ( notifIn instanceof MBeanServerNotification )
{
final MBeanServerNotification notif = (MBeanServerNotification)notifIn;
final ObjectName objectName = notif.getMBeanName();
final String type = notif.getType();
try
{
if ( type.equals( MBeanServerNotification.REGISTRATION_NOTIFICATION ) )
{
listenToIfMatch( objectName );
}
else if ( type.equals( MBeanServerNotification.UNREGISTRATION_NOTIFICATION ) )
{
mListenees.remove( objectName );
}
}
catch( Exception e )
{
// nothing can be done...
}
}
}
}
/**
Reset everything so that no listening is occuring and
all lists are empty.
*/
public synchronized void
cleanup()
{
try
{
if ( mDelegateListener != null )
{
// it's crucial we listen for registration/unregistration events
// so that any patterns are maintained.
getConn().removeNotificationListener(
JMXUtil.getMBeanServerDelegateObjectName(),
mDelegateListener, null, null );
mDelegateListener = null;
}
for( final ObjectName objectName : mListenees )
{
getConn().removeNotificationListener(
objectName, this, mFilter, null);
}
}
catch( JMException e )
{
}
catch( IOException e )
{
}
mListenees.clear();
}
/**
@return a copy of the MBean currently being listened to.
*/
public synchronized Set<ObjectName>
getListenees()
{
final Set<ObjectName> objectNames = new HashSet<ObjectName>();
synchronized( mListenees )
{
objectNames.addAll( mListenees );
}
return( objectNames );
}
/**
@return the MBeanServerConnection in use.
@throws an Exception if no longer alive ( isAlive() returns false).
*/
public final MBeanServerConnection
getMBeanServerConnection()
{
return getConn();
}
protected final MBeanServerConnection
getConn()
{
return mConn;
}
protected final void
checkAlive()
throws IOException
{
if ( ! isAlive() )
{
throw new IOException( "MBeanServerConnection failed" );
}
}
/**
@return true if still listening and the connection is still alive
*/
public boolean
isAlive()
{
boolean isAlive = true;
if ( ! (mConn instanceof MBeanServer) )
{
// remote, check if it is alive
try
{
mConn.isRegistered( JMXUtil.getMBeanServerDelegateObjectName() );
}
catch( Exception e )
{
isAlive = false;
}
}
return isAlive;
}
}
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