org.apache.hadoop.util.StopWatch Maven / Gradle / Ivy
/**
* 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 final Timer timer;
private boolean isStarted;
private long startNanos;
private long currentElapsedNanos;
public StopWatch() {
this(new Timer());
}
/**
* Used for tests to be able to create a StopWatch which does not follow real
* time.
* @param timer The timer to base this StopWatch's timekeeping off of.
*/
public StopWatch(Timer timer) {
this.timer = timer;
}
/**
* 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 = timer.monotonicNowNanos();
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 = timer.monotonicNowNanos();
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 ?
timer.monotonicNowNanos() - startNanos + currentElapsedNanos :
currentElapsedNanos;
}
@Override
public String toString() {
return String.valueOf(now());
}
@Override
public void close() {
if (isStarted) {
stop();
}
}
}