com.wavefront.common.Clock Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of java-lib Show documentation

There is a newer version: 2023-22.3

package com.wavefront.common;

import com.yammer.metrics.Metrics;
import com.yammer.metrics.core.Gauge;
import com.yammer.metrics.core.MetricName;

/**
 * Clock to manage agent time synced with the server.
 *
 * @author Clement Pang ([email protected]).
 */
public abstract class Clock {
  private static Long serverTime;
  private static Long localTime;
  private static Long clockDrift;

  private static Gauge clockDriftGauge;

  public static void set(long serverTime) {
    localTime = System.currentTimeMillis();
    Clock.serverTime = serverTime;
    clockDrift = serverTime - localTime;
    if (clockDriftGauge == null) {
      // doesn't have to be synchronized, ok to initialize clockDriftGauge more than once
      clockDriftGauge = Metrics.newGauge(new MetricName("clock", "", "drift"), new Gauge() {
        @Override
        public Long value() {
          return clockDrift == null ? null : (long)Math.floor(clockDrift / 1000 + 0.5d);
        }
      });
    }
  }

  public static long now() {
    if (serverTime == null) return System.currentTimeMillis();
    else return (System.currentTimeMillis() - localTime) + serverTime;
  }
}