package nova.hotspot;
         

         
import javax.management.ListenerNotFoundException;
         
import javax.management.NotificationEmitter;
         
import javax.management.NotificationListener;
         
import java.lang.management.ManagementFactory;
         
import java.lang.management.MemoryPoolMXBean;
         
import java.util.HashMap;
         
import java.util.Iterator;
         

         
/**
         
 * <p>Hotspot memory usage events.</p>
         
 * <p/>
         
 * Warranty & Liability
         
 * To the extent permitted by applicable law and unless explicitly
         
 * otherwise agreed upon, XLOG Technologies AG makes no warranties
         
 * regarding the provided information. XLOG Technologies AG assumes
         
 * no liability that any problems might be solved with the information
         
 * provided by XLOG Technologies AG.
         
 * <p/>
         
 * Rights & License
         
 * All industrial property rights regarding the information - copyright
         
 * and patent rights in particular - are the sole property of XLOG
         
 * Technologies AG. If the company was not the originator of some
         
 * excerpts, XLOG Technologies AG has at least obtained the right to
         
 * reproduce, change and translate the information.
         
 * <p/>
         
 * Reproduction is restricted to the whole unaltered document. Reproduction
         
 * of the information is only allowed for non-commercial uses. Selling,
         
 * giving away or letting of the execution of the library is prohibited.
         
 * The library can be distributed as part of your applications and libraries
         
 * for execution provided this comment remains unchanged.
         
 * <p/>
         
 * Restrictions
         
 * Only to be distributed with programs that add significant and primary
         
 * functionality to the library. Not to be distributed with additional
         
 * software intended to replace any components of the library.
         
 * <p/>
         
 * Trademarks
         
 * Jekejeke is a registered trademark of XLOG Technologies AG.
         
 */
         
public final class HotspotUsage {
         
    public static HotspotUsage DEFAULT = new HotspotUsage();
         

         
    private final HashMap<String, Long> thresholds = new HashMap<String, Long>();
         
    private int count;
         

         
    /**
         
     * <p>Create a hotspot usage.</p>
         
     */
         
    private HotspotUsage() {
         
        /* do nothing */
         
    }
         

         
    /**
         
     * <p>Add a notification listener.</p>
         
     * <p>If this is the first listener save and init the threshold.</p>
         
     *
         
     * @param listener The listener.
         
     * @param handback The handback.
         
     */
         
    public final void addListener(NotificationListener listener, Object handback) {
         
        synchronized (thresholds) {
         
            if (count == 0) {
         
                Iterator<MemoryPoolMXBean> pool = ManagementFactory.getMemoryPoolMXBeans().iterator();
         
                while (pool.hasNext()) {
         
                    MemoryPoolMXBean pbean = pool.next();
         
                    if (pbean.isUsageThresholdSupported()) {
         
                        long threshold = pbean.getUsageThreshold();
         
                        thresholds.put(pbean.getName(), Long.valueOf(threshold));
         
                        threshold = pbean.getUsage().getMax() * 85 / 100;
         
                        pbean.setUsageThreshold(threshold);
         
                    }
         
                }
         
            }
         
            count++;
         
        }
         
        NotificationEmitter emitter = (NotificationEmitter) ManagementFactory.getMemoryMXBean();
         
        emitter.addNotificationListener(listener, null, handback);
         
    }
         

         
    /**
         
     * <p>Remove a notificatio listener.</p>
         
     * <p>If this is the last listener restore the threshold.</p>
         
     *
         
     * @param listener The listener.
         
     * @param handback The handback.
         
     */
         
    public final void removeListener(NotificationListener listener, Object handback) {
         
        NotificationEmitter emitter = (NotificationEmitter) ManagementFactory.getMemoryMXBean();
         
        try {
         
            emitter.removeNotificationListener(listener, null, handback);
         
        } catch (ListenerNotFoundException e) {
         
            throw new RuntimeException(e);
         
        }
         
        synchronized (thresholds) {
         
            count--;
         
            if (count == 0) {
         
                Iterator<MemoryPoolMXBean> pool = ManagementFactory.getMemoryPoolMXBeans().iterator();
         
                while (pool.hasNext()) {
         
                    MemoryPoolMXBean pbean = pool.next();
         
                    if (pbean.isUsageThresholdSupported()) {
         
                        long threshold = thresholds.get(pbean.getName()).longValue();
         
                        pbean.setUsageThreshold(threshold);
         
                    }
         
                }
         
            }
         
        }
         
    }
         

         
}