org.glassfish.admin.amx.util.jmx.NotificationListenerTracking Maven / Gradle / Ivy

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// Portions Copyright [2019] Payara Foundation and/or affiliates

package org.glassfish.admin.amx.util.jmx;

import javax.management.NotificationFilter;
import javax.management.NotificationListener;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

/**
 */
public class NotificationListenerTracking {
    // NotificationListeners are not unique, so we can't use a Map
    private final List mInfos;

    public NotificationListenerTracking(boolean synchronize) {
        final List infos = new ArrayList();

        mInfos = synchronize ? Collections.synchronizedList(infos) : infos;
    }

    public void addNotificationListener(NotificationListener listener, NotificationFilter filter, Object handback) {
        final NotificationListenerInfo info = new NotificationListenerInfo(listener, filter, handback);

        mInfos.add(info);
    }

    public int getListenerCount() {
        return mInfos.size();
    }

    private boolean listenersEqual(final NotificationListener listener1, final NotificationListener listener2) {
        return (listener1 == listener2);
    }

    private boolean handbacksEqual(final Object handback1, final Object handback2) {
        return (handback1 == handback2);
    }

    /**
    Remove all instances of the specified listener and return
    their corresponding NotificationListenerInfo.
    This behavior matches the behavior of
    {@link javax.management.NotificationEmitter}.

    @return list of NotificationListenerInfo
     */
    public List removeNotificationListener(final NotificationListener listener) {
        final Iterator iter = mInfos.iterator();

        final List results = new ArrayList();

        while (iter.hasNext()) {
            final NotificationListenerInfo info = (NotificationListenerInfo) iter.next();

            if (listenersEqual(listener, info.getListener())) {
                iter.remove();
                results.add(info);
            }
        }

        return (results);
    }

    /**
    Remove the first instance of the specified listener/filter/handback
    combination and return its corresponding NotificationListenerInfo.
    This behavior matches the behavior of
    {@link javax.management.NotificationEmitter}.

    @return list of NotificationListenerInfo
     */
    public NotificationListenerInfo removeNotificationListener(final NotificationListener listener, final NotificationFilter filter, final Object handback) {
        final Iterator iter = mInfos.iterator();
        NotificationListenerInfo result = null;

        while (iter.hasNext()) {
            final NotificationListenerInfo info = (NotificationListenerInfo) iter.next();

            if (listenersEqual(listener, info.getListener()) && handbacksEqual(handback, info.getHandback())) {
                iter.remove();
                result = info;
                break;
            }
        }

        return (result);
    }

}