StopWatch.java
/*
* 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.commons.lang3.time;
import java.util.Objects;
import java.util.concurrent.TimeUnit;
import org.apache.commons.lang3.StringUtils;
/**
* {@link StopWatch} provides a convenient API for timings.
*
* <p>
* To start the watch, call {@link #start()} or {@link StopWatch#createStarted()}. At this point you can:
* </p>
* <ul>
* <li>{@link #split()} the watch to get the time whilst the watch continues in the background. {@link #unsplit()} will remove the effect of the split. At this
* point, these three options are available again.</li>
* <li>{@link #suspend()} the watch to pause it. {@link #resume()} allows the watch to continue. Any time between the suspend and resume will not be counted in
* the total. At this point, these three options are available again.</li>
* <li>{@link #stop()} the watch to complete the timing session.</li>
* </ul>
*
* <p>
* It is intended that the output methods {@link #toString()} and {@link #getTime()} should only be called after stop, split or suspend, however a suitable
* result will be returned at other points.
* </p>
*
* <p>
* NOTE: As from v2.1, the methods protect against inappropriate calls. Thus you cannot now call stop before start, resume before suspend or unsplit before
* split.
* </p>
*
* <ol>
* <li>{@link #split()}, {@link #suspend()}, or {@link #stop()} cannot be invoked twice</li>
* <li>{@link #unsplit()} may only be called if the watch has been {@link #split()}</li>
* <li>{@link #resume()} may only be called if the watch has been {@link #suspend()}</li>
* <li>{@link #start()} cannot be called twice without calling {@link #reset()}</li>
* </ol>
*
* <p>
* This class is not thread-safe
* </p>
*
* @since 2.0
*/
public class StopWatch {
/**
* Enumeration type which indicates the split status of a StopWatch.
*/
private enum SplitState {
SPLIT, UNSPLIT
}
/**
* Enumeration type which indicates the status of a StopWatch.
*/
private enum State {
RUNNING {
@Override
boolean isStarted() {
return true;
}
@Override
boolean isStopped() {
return false;
}
@Override
boolean isSuspended() {
return false;
}
},
STOPPED {
@Override
boolean isStarted() {
return false;
}
@Override
boolean isStopped() {
return true;
}
@Override
boolean isSuspended() {
return false;
}
},
SUSPENDED {
@Override
boolean isStarted() {
return true;
}
@Override
boolean isStopped() {
return false;
}
@Override
boolean isSuspended() {
return true;
}
},
UNSTARTED {
@Override
boolean isStarted() {
return false;
}
@Override
boolean isStopped() {
return true;
}
@Override
boolean isSuspended() {
return false;
}
};
/**
* Tests whether the StopWatch is started. A suspended StopWatch is also started.
*
* @return boolean If the StopWatch is started.
*/
abstract boolean isStarted();
/**
* Tests whether the StopWatch is stopped. A StopWatch which is not yet started and explicitly stopped is considered stopped.
*
* @return boolean If the StopWatch is stopped.
*/
abstract boolean isStopped();
/**
* Tests whether the StopWatch is suspended.
*
* @return boolean If the StopWatch is suspended.
*/
abstract boolean isSuspended();
}
private static final long NANO_2_MILLIS = 1000000L;
/**
* Creates a StopWatch.
*
* @return StopWatch a StopWatch.
*
* @since 3.10
*/
public static StopWatch create() {
return new StopWatch();
}
/**
* Creates and starts a StopWatch.
*
* @return StopWatch a started StopWatch.
*
* @since 3.5
*/
public static StopWatch createStarted() {
final StopWatch sw = new StopWatch();
sw.start();
return sw;
}
/**
* A message for string presentation.
*
* @since 3.10
*/
private final String message;
/**
* The current running state of the StopWatch.
*/
private State runningState = State.UNSTARTED;
/**
* Whether the StopWatch has a split time recorded.
*/
private SplitState splitState = SplitState.UNSPLIT;
/**
* The start time in nanoseconds.
*/
private long startTimeNanos;
/**
* The start time in milliseconds.
* <p>
* nanoTime is only for elapsed time so we need to also store the currentTimeMillis to maintain the old getStartTime API.
* </p>
*/
private long startTimeMillis;
/**
* The end time in milliseconds.
* <p>
* nanoTime is only for elapsed time so we need to also store the currentTimeMillis to maintain the old getStartTime API.
* </p>
*/
private long stopTimeMillis;
/**
* The stop time in nanoseconds.
*/
private long stopTimeNanos;
/**
* Constructor.
*/
public StopWatch() {
this(null);
}
/**
* Constructs a new instance.
*
* @param message A message for string presentation.
* @since 3.10
*/
public StopWatch(final String message) {
this.message = message;
}
/**
* Formats the split time with {@link DurationFormatUtils#formatDurationHMS}.
*
* @return the split time formatted by {@link DurationFormatUtils#formatDurationHMS}.
* @since 3.10
*/
public String formatSplitTime() {
return DurationFormatUtils.formatDurationHMS(getSplitTime());
}
/**
* Formats the time formatted with {@link DurationFormatUtils#formatDurationHMS}.
*
* @return the time formatted by {@link DurationFormatUtils#formatDurationHMS}.
* @since 3.10
*/
public String formatTime() {
return DurationFormatUtils.formatDurationHMS(getTime());
}
/**
* Gets the message for string presentation.
*
* @return the message for string presentation.
* @since 3.10
*/
public String getMessage() {
return message;
}
/**
* Gets the <em>elapsed</em> time in nanoseconds.
*
* <p>
* This is either the time between the start and the moment this method is called, or the amount of time between start and stop.
* </p>
*
* @return the <em>elapsed</em> time in nanoseconds.
* @see System#nanoTime()
* @since 3.0
*/
public long getNanoTime() {
if (this.runningState == State.STOPPED || this.runningState == State.SUSPENDED) {
return this.stopTimeNanos - this.startTimeNanos;
}
if (this.runningState == State.UNSTARTED) {
return 0;
}
if (this.runningState == State.RUNNING) {
return System.nanoTime() - this.startTimeNanos;
}
throw new IllegalStateException("Illegal running state has occurred.");
}
/**
* Gets the split time in nanoseconds.
*
* <p>
* This is the time between start and latest split.
* </p>
*
* @return the split time in nanoseconds
*
* @throws IllegalStateException if the StopWatch has not yet been split.
* @since 3.0
*/
public long getSplitNanoTime() {
if (this.splitState != SplitState.SPLIT) {
throw new IllegalStateException("Stopwatch must be split to get the split time.");
}
return this.stopTimeNanos - this.startTimeNanos;
}
/**
* Gets the split time on the StopWatch.
*
* <p>
* This is the time between start and latest split.
* </p>
*
* @return the split time in milliseconds
*
* @throws IllegalStateException if the StopWatch has not yet been split.
* @since 2.1
*/
public long getSplitTime() {
return nanosToMillis(getSplitNanoTime());
}
/**
* Gets the time this StopWatch was started in milliseconds, between the current time and midnight, January 1, 1970 UTC.
*
* @return the time this StopWatch was started in milliseconds, between the current time and midnight, January 1, 1970 UTC.
* @throws IllegalStateException if this StopWatch has not been started
* @since 2.4
*/
public long getStartTime() {
if (this.runningState == State.UNSTARTED) {
throw new IllegalStateException("Stopwatch has not been started");
}
// stopTimeNanos stores System.nanoTime() for elapsed time
return this.startTimeMillis;
}
/**
* Gets the time this StopWatch was stopped in milliseconds, between the current time and midnight, January 1, 1970 UTC.
*
* @return the time this StopWatch was started in milliseconds, between the current time and midnight, January 1, 1970 UTC.
* @throws IllegalStateException if this StopWatch has not been started
* @since 3.12.0
*/
public long getStopTime() {
if (this.runningState == State.UNSTARTED) {
throw new IllegalStateException("Stopwatch has not been started");
}
// stopTimeNanos stores System.nanoTime() for elapsed time
return this.stopTimeMillis;
}
/**
* Gets the time on the StopWatch.
*
* <p>
* This is either the time between the start and the moment this method is called, or the amount of time between start and stop.
* </p>
*
* @return the time in milliseconds
*/
public long getTime() {
return nanosToMillis(getNanoTime());
}
/**
* Gets the time in the specified TimeUnit.
*
* <p>
* This is either the time between the start and the moment this method is called, or the amount of time between start and stop. The resulting time will be
* expressed in the desired TimeUnit with any remainder rounded down. For example, if the specified unit is {@code TimeUnit.HOURS} and the StopWatch time is
* 59 minutes, then the result returned will be {@code 0}.
* </p>
*
* @param timeUnit the unit of time, not null
* @return the time in the specified TimeUnit, rounded down
* @since 3.5
*/
public long getTime(final TimeUnit timeUnit) {
return timeUnit.convert(getNanoTime(), TimeUnit.NANOSECONDS);
}
/**
* Tests whether the StopWatch is started. A suspended StopWatch is also started watch.
*
* @return boolean If the StopWatch is started.
* @since 3.2
*/
public boolean isStarted() {
return runningState.isStarted();
}
/**
* Tests whether StopWatch is stopped. The StopWatch which's not yet started and explicitly stopped StopWatch is considered as stopped.
*
* @return boolean If the StopWatch is stopped.
* @since 3.2
*/
public boolean isStopped() {
return runningState.isStopped();
}
/**
* Tests whether the StopWatch is suspended.
*
* @return boolean If the StopWatch is suspended.
* @since 3.2
*/
public boolean isSuspended() {
return runningState.isSuspended();
}
/**
* Converts nanoseconds to milliseconds.
*
* @param nanos nanoseconds to convert.
* @return milliseconds conversion result.
*/
private long nanosToMillis(long nanos) {
return nanos / NANO_2_MILLIS;
}
/**
* Resets the StopWatch. Stops it if need be.
*
* <p>
* This method clears the internal values to allow the object to be reused.
* </p>
*/
public void reset() {
this.runningState = State.UNSTARTED;
this.splitState = SplitState.UNSPLIT;
}
/**
* Resumes the StopWatch after a suspend.
*
* <p>
* This method resumes the watch after it was suspended. The watch will not include time between the suspend and resume calls in the total time.
* </p>
*
* @throws IllegalStateException if the StopWatch has not been suspended.
*/
public void resume() {
if (this.runningState != State.SUSPENDED) {
throw new IllegalStateException("Stopwatch must be suspended to resume. ");
}
this.startTimeNanos += System.nanoTime() - this.stopTimeNanos;
this.runningState = State.RUNNING;
}
/**
* Splits the time.
*
* <p>
* This method sets the stop time of the watch to allow a time to be extracted. The start time is unaffected, enabling {@link #unsplit()} to continue the
* timing from the original start point.
* </p>
*
* @throws IllegalStateException if the StopWatch is not running.
*/
public void split() {
if (this.runningState != State.RUNNING) {
throw new IllegalStateException("Stopwatch is not running. ");
}
this.stopTimeNanos = System.nanoTime();
this.splitState = SplitState.SPLIT;
}
/**
* Starts the StopWatch.
*
* <p>
* This method starts a new timing session, clearing any previous values.
* </p>
*
* @throws IllegalStateException if the StopWatch is already running.
*/
public void start() {
if (this.runningState == State.STOPPED) {
throw new IllegalStateException("Stopwatch must be reset before being restarted. ");
}
if (this.runningState != State.UNSTARTED) {
throw new IllegalStateException("Stopwatch already started. ");
}
this.startTimeNanos = System.nanoTime();
this.startTimeMillis = System.currentTimeMillis();
this.runningState = State.RUNNING;
}
/**
* Stops the StopWatch.
*
* <p>
* This method ends a new timing session, allowing the time to be retrieved.
* </p>
*
* @throws IllegalStateException if the StopWatch is not running.
*/
public void stop() {
if (this.runningState != State.RUNNING && this.runningState != State.SUSPENDED) {
throw new IllegalStateException("Stopwatch is not running. ");
}
if (this.runningState == State.RUNNING) {
this.stopTimeNanos = System.nanoTime();
this.stopTimeMillis = System.currentTimeMillis();
}
this.runningState = State.STOPPED;
}
/**
* Suspends the StopWatch for later resumption.
*
* <p>
* This method suspends the watch until it is resumed. The watch will not include time between the suspend and resume calls in the total time.
* </p>
*
* @throws IllegalStateException if the StopWatch is not currently running.
*/
public void suspend() {
if (this.runningState != State.RUNNING) {
throw new IllegalStateException("Stopwatch must be running to suspend. ");
}
this.stopTimeNanos = System.nanoTime();
this.stopTimeMillis = System.currentTimeMillis();
this.runningState = State.SUSPENDED;
}
/**
* Gets a summary of the split time that the StopWatch recorded as a string.
*
* <p>
* The format used is ISO 8601-like, [<i>message</i> ]<i>hours</i>:<i>minutes</i>:<i>seconds</i>.<i>milliseconds</i>.
* </p>
*
* @return the split time as a String
* @since 2.1
* @since 3.10 Returns the prefix {@code "message "} if the message is set.
*/
public String toSplitString() {
final String msgStr = Objects.toString(message, StringUtils.EMPTY);
final String formattedTime = formatSplitTime();
return msgStr.isEmpty() ? formattedTime : msgStr + StringUtils.SPACE + formattedTime;
}
/**
* Gets a summary of the time that the StopWatch recorded as a string.
*
* <p>
* The format used is ISO 8601-like, [<i>message</i> ]<i>hours</i>:<i>minutes</i>:<i>seconds</i>.<i>milliseconds</i>.
* </p>
*
* @return the time as a String
* @since 3.10 Returns the prefix {@code "message "} if the message is set.
*/
@Override
public String toString() {
final String msgStr = Objects.toString(message, StringUtils.EMPTY);
final String formattedTime = formatTime();
return msgStr.isEmpty() ? formattedTime : msgStr + StringUtils.SPACE + formattedTime;
}
/**
* Removes a split.
*
* <p>
* This method clears the stop time. The start time is unaffected, enabling timing from the original start point to continue.
* </p>
*
* @throws IllegalStateException if the StopWatch has not been split.
*/
public void unsplit() {
if (this.splitState != SplitState.SPLIT) {
throw new IllegalStateException("Stopwatch has not been split. ");
}
this.splitState = SplitState.UNSPLIT;
}
}