1 /* 2 * Copyright (C) 2011 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.common.base; 18 19 import com.google.common.annotations.Beta; 20 import com.google.common.annotations.GwtCompatible; 21 22 /** 23 * A time source; returns a time value representing the number of nanoseconds 24 * elapsed since some fixed but arbitrary point in time. 25 * 26 * @author Kevin Bourrillion 27 * @since 10.0 28 * (<a href="http://code.google.com/p/guava-libraries/wiki/Compatibility" 29 * >mostly source-compatible</a> since 9.0) 30 */ 31 @Beta 32 @GwtCompatible 33 public abstract class Ticker { 34 /** 35 * Constructor for use by subclasses. 36 */ Ticker()37 protected Ticker() {} 38 39 /** 40 * Returns the number of nanoseconds elapsed since this ticker's fixed 41 * point of reference. 42 */ read()43 public abstract long read(); 44 45 /** 46 * A ticker that reads the current time using {@link System#nanoTime}. 47 * 48 * @since 10.0 49 */ systemTicker()50 public static Ticker systemTicker() { 51 return SYSTEM_TICKER; 52 } 53 54 private static final Ticker SYSTEM_TICKER = new Ticker() { 55 @Override 56 public long read() { 57 return Platform.systemNanoTime(); 58 } 59 }; 60 } 61