| /* |
| * 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(); |
| } |
| }; |
| } |