content: /*
   * Tencent is pleased to support the open source community by making Angel available.
   *
   * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in 
   * compliance with the License. You may obtain a copy of the License at
   *
   * https://opensource.org/licenses/Apache-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License
   * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
   * or implied. See the License for the specific language governing permissions and limitations under
   * the License.
   *
   */
  
  
  package com.tencent.angel.utils;
  
  
  /**
   * Utility methods for getting the time and computing intervals.
   */
  public final class Time {
  
    /**
     * Current system time. Do not use this to calculate a duration or interval to sleep, because it
     * will be broken by settimeofday. Instead, use monotonicNow.
     *
     * @return current time in msec.
     */
    public static long now() {
      return System.currentTimeMillis();
    }
  
    /**
     * Current time from some arbitrary time base in the past, counting in milliseconds, and not
     * affected by settimeofday or similar system clock changes. This is appropriate to use when
     * computing how much longer to wait for an interval to expire.
     *
     * @return a monotonic clock that counts in milliseconds.
     */
    public static long monotonicNow() {
      final long NANOSECONDS_PER_MILLISECOND = 1000000;
  
      return System.nanoTime() / NANOSECONDS_PER_MILLISECOND;
    }
  }