content: /*
   *  Copyright (c) 2021 Freya Arbjerg and contributors
   *
   *  Permission is hereby granted, free of charge, to any person obtaining a copy
   *  of this software and associated documentation files (the "Software"), to deal
   *  in the Software without restriction, including without limitation the rights
   *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   *  copies of the Software, and to permit persons to whom the Software is
   *  furnished to do so, subject to the following conditions:
   *
   *  The above copyright notice and this permission notice shall be included in all
   *  copies or substantial portions of the Software.
   *
   *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   *  SOFTWARE.
   *
   */
  
  package lavalink.server.metrics;
  
  import com.sun.management.GarbageCollectionNotificationInfo;
  import com.sun.management.GcInfo;
  import io.prometheus.client.Collector;
  import io.prometheus.client.Histogram;
  
  import javax.management.Notification;
  import javax.management.NotificationListener;
  import javax.management.openmbean.CompositeData;
  
  import static com.sun.management.GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION;
  import static com.sun.management.GarbageCollectionNotificationInfo.from;
  
  /**
   * Created by napster on 21.05.18.
   * <p>
   * General idea taken from {@link com.sedmelluq.discord.lavaplayer.tools.GarbageCollectionMonitor}, thanks!
   */
  public class GcNotificationListener implements NotificationListener {
  
      private final Histogram gcPauses = Histogram.build()
          .name("lavalink_gc_pauses_seconds")
          .help("Garbage collection pauses by buckets")
          .buckets(0.025, 0.050, 0.100, 0.200, 0.400, 0.800, 1.600)
          .register();
  
      @Override
      public void handleNotification(Notification notification, Object handback) {
          if (GARBAGE_COLLECTION_NOTIFICATION.equals(notification.getType())) {
              GarbageCollectionNotificationInfo notificationInfo = from((CompositeData) notification.getUserData());
              GcInfo info = notificationInfo.getGcInfo();
  
              if (info != null && !"No GC".equals(notificationInfo.getGcCause())) {
                  gcPauses.observe(info.getDuration() / Collector.MILLISECONDS_PER_SECOND);
              }
          }
      }
  }
  