/*
* Copyright (C) 2011 The Guava Authors
*
* 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.google.common.base;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
/**
* A time source; returns a time value representing the number of nanoseconds elapsed since some
* fixed but arbitrary point in time. Note that most users should use {@link Stopwatch} instead of
* interacting with this class directly.
*
* <p><b>Warning:</b> this interface can only be used to measure elapsed time, not wall time.
*
* @author Kevin Bourrillion
* @since 10.0
* (<a href="http://code.google.com/p/guava-libraries/wiki/Compatibility"
* >mostly source-compatible</a> since 9.0)
*/
@Beta
@GwtCompatible
public abstract class Ticker {
/**
* Constructor for use by subclasses.
*/
protected Ticker() {}
/**
* Returns the number of nanoseconds elapsed since this ticker's fixed
* point of reference.
*/
public abstract long read();
/**
* A ticker that reads the current time using {@link System#nanoTime}.
*
* @since 10.0
*/
public static Ticker systemTicker() {
return SYSTEM_TICKER;
}
private static final Ticker SYSTEM_TICKER = new Ticker() {
@Override
public long read() {
return Platform.systemNanoTime();
}
};
}