/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
*
* http://www.apache.org/licenses/LICENSE-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 org.apache.flink.runtime.util.clock;
/**
* A clock that gives access to time. This clock returns two flavors of time:
*
* <p><b>Absolute Time:</b> This refers to real world wall clock time, and it typically
* derived from a system clock. It is subject to clock drift and inaccuracy, and can jump
* if the system clock is adjusted.
*
* <p><b>Relative Time:</b> This time advances at the same speed as the <i>absolute time</i>,
* but the timestamps can only be referred to relative to each other. The timestamps have
* no absolute meaning and cannot be compared across JVM processes. The source for the
* timestamps is not affected by adjustments to the system clock, so it never jumps.
*/
public abstract class Clock {
public abstract long absoluteTimeMillis();
public abstract long relativeTimeMillis();
public abstract long relativeTimeNanos();
}