Glassfish example source code file (MBeanTracker.java)

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Java - Glassfish tags/keywords

concurrentmap, exception, exception, hashset, management, mbeanserver, mbeanservernotification, mbeantracker, object, objectname, objectname, set, set, string, string, threading, threads, util

The Glassfish MBeanTracker.java source code

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 *
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 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
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 * file and include the License file at packager/legal/LICENSE.txt.
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 * GPL Classpath Exception:
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 * exception as provided by Oracle in the GPL Version 2 section of the License
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 *
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package org.glassfish.admin.amx.base;


import java.util.Collections;
import javax.management.*;

import java.util.Set;
import java.util.HashSet;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentHashMap;

import org.glassfish.external.arc.Stability;
import org.glassfish.external.arc.Taxonomy;
import org.glassfish.admin.amx.core.Util;
import org.glassfish.admin.amx.util.jmx.JMXUtil;

import org.glassfish.admin.amx.core.AMXMBeanMetadata;
import org.glassfish.external.amx.AMX;

/**
    Tracks the entire MBean parent/child hierarachy so that individual MBeans need not do so.
    Can supply parents and children of any MBean, used by all AMX implementations.
 */
@Taxonomy(stability = Stability.NOT_AN_INTERFACE)
@AMXMBeanMetadata(singleton=true, globalSingleton=true, leaf=true)
public final class MBeanTracker implements NotificationListener, MBeanRegistration, MBeanTrackerMBean
{
    private static void debug(final Object o)
    {
        System.out.println( "" + o);
    }
    
    /** maps a parent ObjectName to a Set of children */
    final ConcurrentMap<ObjectName,Set mParentChildren;
    
    /** maps a child to its parent, needed because when unregistered we can't obtain parent */
    final ConcurrentMap<ObjectName,ObjectName>      mChildParent;
    
    private volatile MBeanServer mServer;
    private volatile ObjectName  mObjectName;
    
    private final String mDomain;
    
    private volatile boolean mEmitMBeanStatus;
    
    public MBeanTracker( final String jmxDomain )
    {
        mParentChildren = new ConcurrentHashMap<ObjectName,Set();
        mChildParent    = new ConcurrentHashMap<ObjectName,ObjectName>();
        
        mDomain = jmxDomain;
        
        mEmitMBeanStatus = false;
    }
    
    public boolean getEmitMBeanStatus() { return mEmitMBeanStatus; }
    
    public void setEmitMBeanStatus( final boolean emit )
    {
        mEmitMBeanStatus = emit;
    }
    
    public void handleNotification(final Notification notifIn, final Object handback)
    {
        if ( notifIn instanceof MBeanServerNotification )
        {
            final MBeanServerNotification notif = (MBeanServerNotification)notifIn;
            
            final String type = notif.getType();
            final ObjectName objectName = notif.getMBeanName();
            
            if ( isRelevantMBean(objectName) )
            {
                // what happens if an MBean is removed before we can add it
                // eg the MBeanServer uses more than one thread to deliver notifications
                // to use? Even if we synchronize this method, the remove could still arrive
                // first and there's nothing we could do about it.
                if ( type.equals( MBeanServerNotification.REGISTRATION_NOTIFICATION ) )
                {
                    if ( mEmitMBeanStatus )
                    {
                        System.out.println( "AMX MBean registered: " + objectName );
                    }
                    addChild(objectName);
                }
                else if ( type.equals( MBeanServerNotification.UNREGISTRATION_NOTIFICATION ) )
                {
                    if ( mEmitMBeanStatus )
                    {
                        System.out.println( "AMX MBean UNregistered: " + objectName );
                    }
                    removeChild(objectName);
                }
            }
        }
    }
    
	public ObjectName preRegister(
		final MBeanServer	server,
		final ObjectName	nameIn)
		throws Exception
	{
		mServer			= server;
        mObjectName     = nameIn;
		return( nameIn );
	}
    
		public final void
	postRegister( final Boolean registrationSucceeded )
	{	
		if ( registrationSucceeded.booleanValue() )
		{
            try
            {
                mServer.addNotificationListener( JMXUtil.getMBeanServerDelegateObjectName(), this, null, null );
            }
            catch( Exception e )
            {
                throw new RuntimeException("Could not register with MBeanServerDelegate", e);
            }
            //debug( "MBeanTracker: registered as " + mObjectName );
		}
        // populate our list
		final ObjectName	pattern	= Util.newObjectNamePattern( mDomain, "" );
		final Set<ObjectName>	names	= JMXUtil.queryNames( mServer, pattern, null );
        //debug( "MBeanTracker: found MBeans: " + names.size() );
        for( final ObjectName o : names )
        {
            addChild(o);
        }
	}
    
	public final void preDeregister() throws Exception
    {
        mServer.removeNotificationListener( mObjectName, this);
    }
    
	public final void postDeregister() {
    }
    
    private boolean isRelevantMBean(final ObjectName child)
    {
        return child != null && mDomain.equals( child.getDomain() );
    }
    
    private void addChild(final ObjectName child)
    {
        ObjectName parent = null;
        try {
            parent = (ObjectName)mServer.getAttribute(child, AMX.ATTR_PARENT);
        }
        catch( final Exception e )
        {
            // nothing to be done, MBean gone missing, badly implemented, etc.
            //System.out.println( "No Parent for: " + child );
        }
        
        if ( parent != null )
        {
            synchronized(this)
            {
                mChildParent.put(child, parent);
                Set<ObjectName> children = mParentChildren.get(parent);
                if ( children == null )
                {
                    children = new HashSet<ObjectName>();
                    mParentChildren.put(parent, children);
                }
                children.add(child);
                //debug( "MBeanTracker: ADDED " + child + " with parent " + parent );
            }
        }
    }
    
    /**
        Must be 'synchronized' because we're working on two different Maps.
     */
    private synchronized ObjectName removeChild(final ObjectName child)
    {
        final ObjectName parent = mChildParent.remove(child);
        if ( parent != null )
        {
            final Set<ObjectName> children = mParentChildren.get(parent);
            if ( children != null )
            {
                children.remove(child);
                if ( children.size() == 0 )
                {
                    mParentChildren.remove(parent);
                    //debug( "MBeanTracker: REMOVED " + child + " from parent " + parent );
                }
            }
        }
        return parent;
    }
    
    public ObjectName getParentOf(final ObjectName child)
    {
        return mChildParent.get(child);
    }
    
        public synchronized Set<ObjectName>
    getChildrenOf(final ObjectName parent)
    {
        final Set<ObjectName> children = mParentChildren.get(parent) ;
        if ( children == null )
        {
            return Collections.emptySet();
        }
        
        return new HashSet<ObjectName>(children);
    }
}