/*
 * ====================================================================
 *
 * 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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 *    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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 * [Additional notices, if required by prior licensing conditions]
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package org.apache.commons.modeler;


import java.util.HashSet;

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>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);
        synchronized (names) {
            if (names.size() < 1)
                return (true);
            else
                return (names.contains(notification.getType()));
        }

    }


}