Helper HotspotUsage

Jan Burse, created Apr 18. 2019
package matula.util.swing;
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 GmbH makes no warranties
* regarding the provided information. XLOG Technologies GmbH assumes
* no liability that any problems might be solved with the information
* provided by XLOG Technologies GmbH.
* <p/>
* Rights & License
* All industrial property rights regarding the information - copyright
* and patent rights in particular - are the sole property of XLOG
* Technologies GmbH. If the company was not the originator of some
* excerpts, XLOG Technologies GmbH 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 GmbH.
*/
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);
}
}
}
}
}
}

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