content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.clock;
  
  import java.time.Clock;
  import java.time.Instant;
  import java.time.ZoneId;
  import java.util.concurrent.TimeUnit;
  
  /**
   * A monotonically increasing clock for calculating elapsed time.
   * NOTE: this is not related to system time so the value returned cannot be used for representing
   * date time. The time can be different across JVM. Do not use it for across processes/machines
   * calculation.
   */
  public final class ElapsedTimeClock extends Clock {
    @Override
    public long millis() {
      return TimeUnit.MILLISECONDS.convert(System.nanoTime(), TimeUnit.NANOSECONDS);
    }
  
    @Override
    public ZoneId getZone() {
      return null;
    }
  
    @Override
    public Clock withZone(ZoneId zone) {
      return null;
    }
  
    @Override
    public Instant instant() {
      return null;
    }
  }
  