costin 2003/01/05 22:01:03
Added: modeler/src/java/org/apache/commons/modeler
FixedNotificationFilter.java
Log:
One of the biggest problems with JMX is the way the filter is specified.
When a listener is registered - it can specify a filter, and the filter
will be called before calling the listener.
The problem is - we have no way to optimize the calls. The filter is almost
useless - it's just one extra call that could be done in the listener
itslef.
FixedNotificationFilter is one way around the problem. If we detect a filter
is of this type - we'll know that we can find out what notifications will
be accepted when the listener is added, and avoid calling all filters for all
notifications.
If anyone knows of a better way - please let me know.
Revision Changes Path
1.1
jakarta-commons/modeler/src/java/org/apache/commons/modeler/FixedNotificationFilter.java
Index: FixedNotificationFilter.java
===================================================================
/*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
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* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
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* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
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* the documentation and/or other materials provided with the
* distribution.
*
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* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
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* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
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* This software consists of voluntary contributions made by many
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*
* [Additional notices, if required by prior licensing conditions]
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package org.apache.commons.modeler;
import java.util.HashSet;
import javax.management.AttributeChangeNotification;
import javax.management.Notification;
import javax.management.NotificationFilter;
/**
* Special NotificationFilter that allows modeler to optimize its notifications.
*
* This class is immutable - after you construct it it'll filter based on
* a fixed set of notification names.
*
* The JMX specification requires the filters to be called before the
* notifications are sent. We can call this filter well in advance, when
* the listener is added. Based on the result we can maintain separate
* channels for each notification - and reduce the overhead.
*
* @author Costin Manolache
*/
public class FixedNotificationFilter implements NotificationFilter {
/**
* The set of attribute names that are accepted by this filter. If this
* list is empty, all attribute names are accepted.
*/
private HashSet names = new HashSet();
String namesA[]=null;
/**
* Construct a new filter that accepts only the specified notification
* names.
*
* @param names Names of the notification types
*/
public FixedNotificationFilter(String names[]) {
super();
}
/**
* Return the set of names that are accepted by this filter. If this
* filter accepts all attribute names, a zero length array will be
* returned.
*/
public String[] getNames() {
synchronized (names) {
return ((String[]) names.toArray(new String[names.size()]));
}
}
/**
* <p>Test whether notification enabled for this event.
* Return true if:</p>
* <ul>
* <li>This is an attribute change notification</li>
* <li>Either the set of accepted names is empty (implying that all
* attribute names are of interest) or the set of accepted names
* includes the name of the attribute in this notification</li>
* </ul>
*/
public boolean isNotificationEnabled(Notification notification) {
if (notification == null)
return (false);
if (!(notification instanceof AttributeChangeNotification))
return (false);
AttributeChangeNotification acn =
(AttributeChangeNotification) notification;
if (!AttributeChangeNotification.ATTRIBUTE_CHANGE.equals(acn.getType()))
return (false);
synchronized (names) {
if (names.size() < 1)
return (true);
else
return (names.contains(acn.getAttributeName()));
}
}
}
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