| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.hadoop.util; |
| |
| import java.io.Closeable; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * A simplified StopWatch implementation which can measure times in nanoseconds. |
| */ |
| public class StopWatch implements Closeable { |
| private boolean isStarted; |
| private long startNanos; |
| private long currentElapsedNanos; |
| |
| public StopWatch() { |
| } |
| |
| /** |
| * The method is used to find out if the StopWatch is started. |
| * @return boolean If the StopWatch is started. |
| */ |
| public boolean isRunning() { |
| return isStarted; |
| } |
| |
| /** |
| * Start to measure times and make the state of stopwatch running. |
| * @return this instance of StopWatch. |
| */ |
| public StopWatch start() { |
| if (isStarted) { |
| throw new IllegalStateException("StopWatch is already running"); |
| } |
| isStarted = true; |
| startNanos = System.nanoTime(); |
| return this; |
| } |
| |
| /** |
| * Stop elapsed time and make the state of stopwatch stop. |
| * @return this instance of StopWatch. |
| */ |
| public StopWatch stop() { |
| if (!isStarted) { |
| throw new IllegalStateException("StopWatch is already stopped"); |
| } |
| long now = System.nanoTime(); |
| isStarted = false; |
| currentElapsedNanos += now - startNanos; |
| return this; |
| } |
| |
| /** |
| * Reset elapsed time to zero and make the state of stopwatch stop. |
| * @return this instance of StopWatch. |
| */ |
| public StopWatch reset() { |
| currentElapsedNanos = 0; |
| isStarted = false; |
| return this; |
| } |
| |
| /** |
| * @return current elapsed time in specified timeunit. |
| */ |
| public long now(TimeUnit timeUnit) { |
| return timeUnit.convert(now(), TimeUnit.NANOSECONDS); |
| |
| } |
| |
| /** |
| * @return current elapsed time in nanosecond. |
| */ |
| public long now() { |
| return isStarted ? |
| System.nanoTime() - startNanos + currentElapsedNanos : |
| currentElapsedNanos; |
| } |
| |
| @Override |
| public String toString() { |
| return String.valueOf(now()); |
| } |
| |
| @Override |
| public void close() { |
| if (isStarted) { |
| stop(); |
| } |
| } |
| } |