com.netflix.spectator.api.Clock Maven / Gradle / Ivy
/**
* Copyright 2015 Netflix, Inc.
*
* 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
*
* 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 com.netflix.spectator.api;
/**
* A timing source that can be used to access the current wall time as well as a high resolution
* monotonic time to measuring elapsed times. Most of the time the {@link #SYSTEM} implementation
* that calls the builtin java methods is probably the right one to use. Other implementations
* would typically only get used for unit tests or other cases where precise control of the clock
* is needed.
*/
public interface Clock {
/**
* Current wall time in milliseconds since the epoch. Typically equivalent to
* System.currentTimeMillis.
*/
long wallTime();
/**
* Current time from a monotonic clock source. The value is only meaningful when compared with
* another snapshot to determine the elapsed time for an operation. The difference between two
* samples will have a unit of nanoseconds. The returned value is typically equivalent to
* System.nanoTime.
*/
long monotonicTime();
/**
* Default clock implementation based on corresponding calls in {@link java.lang.System}.
*/
Clock SYSTEM = new Clock() {
public long wallTime() {
return System.currentTimeMillis();
}
public long monotonicTime() {
return System.nanoTime();
}
};
}