org.glassfish.admin.amx.util.jmx.NotificationListenerBase Maven / Gradle / Ivy
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// Portions Copyright [2019] Payara Foundation and/or affiliates
package org.glassfish.admin.amx.util.jmx;
import java.io.IOException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import javax.management.InstanceNotFoundException;
import javax.management.JMException;
import javax.management.MBeanServer;
import javax.management.MBeanServerConnection;
import javax.management.MBeanServerNotification;
import javax.management.Notification;
import javax.management.NotificationFilter;
import javax.management.NotificationListener;
import javax.management.ObjectName;
import org.glassfish.admin.amx.util.SetUtil;
/**
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.
Caller should call {@link #cleanup} when done, because
a listener is maintained on the MBeanServer delegate.
*/
public abstract class NotificationListenerBase implements NotificationListener {
private final MBeanServerConnection mConn;
/** actual MBean ObjectNames, not patterns */
private final Set mListenees;
/** targets as specified by caller, may be a pattern or fixed ObjectName */
private final ObjectName mPattern;
private final NotificationFilter mFilter;
private RegistrationListener mDelegateListener;
private volatile boolean mSetupListening;
/**
Calls this( conn, listenTo, null, null ).
Instantiating code must call setupListening() in order to initiate
listening
*/
protected NotificationListenerBase(final String name, final MBeanServerConnection conn, final ObjectName pattern) throws IOException {
this(name, conn, pattern, null);
}
/**
Listen to all MBean(s) which match the pattern 'listenTo'.
Instantiating code must call setupListening() in order to initiate
listening
@param name 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 IOException
{
mConn = conn;
mPattern = pattern;
mFilter = filter;
mDelegateListener = null;
mSetupListening = false;
mListenees = Collections.synchronizedSet(new HashSet());
// test connection for validity
if (!conn.isRegistered(JMXUtil.getMBeanServerDelegateObjectName()))
{
throw new IllegalArgumentException();
}
}
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 s;
if (mPattern.isPattern())
{
s = JMXUtil.queryNames(getConn(), mPattern, null);
}
else
{
s = SetUtil.newSet(mPattern);
}
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 {
@Override
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 getListenees()
{
final Set objectNames = new HashSet();
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;
}
}