com.yahoo.concurrent.Timer Maven / Gradle / Ivy
// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.concurrent;
import java.time.Clock;
import java.time.Instant;
import java.util.concurrent.TimeUnit;
/**
* This interface wraps access to some timer that can be used to measure elapsed time, in milliseconds. This
* abstraction allows for unit testing the behavior of time-based constructs.
*
* @author Simon Thoresen Hult
*/
public interface Timer {
/**
* Returns the current value of some arbitrary timer, in milliseconds. This method can only be used to measure
* elapsed time and is not related to any other notion of system or wall-clock time.
*
* @return The current value of the timer, in milliseconds.
*/
long milliTime();
long creationNanos = System.nanoTime(); // Avoid monotonic timer overflow for the first 146 years of JVM uptime.
Timer monotonic = () -> TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - creationNanos);
static Timer wrap(Clock original) { return original::millis; }
default Instant instant() { return Instant.ofEpochMilli(milliTime()); }
}