panda.lang.time.StopWatch Maven / Gradle / Ivy
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package panda.lang.time;
/**
*
* StopWatch provides a convenient API for timings.
*
*
*
* To start the watch, call {@link #start()}. At this point you can:
*
*
* - {@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.
* - {@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.
* - {@link #stop()} the watch to complete the timing session.
*
*
*
* 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.
*
*
*
* NOTE: The methods protect against inappropriate calls. Thus you cannot now call stop before start,
* resume before suspend or unsplit before split.
*
*
*
* 1. split(), suspend(), or stop() cannot be invoked twice
* 2. unsplit() may only be called if the watch has been split()
* 3. resume() may only be called if the watch has been suspend()
* 4. start() cannot be called twice without calling reset()
*
*
* This class is not thread-safe
*
*/
public class StopWatch {
/**
* Enumeration type which indicates the status of stopwatch.
*/
private enum State {
UNSTARTED {
@Override
boolean isStarted() {
return false;
}
@Override
boolean isStopped() {
return true;
}
@Override
boolean isSuspended() {
return false;
}
},
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;
}
};
/**
*
* The method is used to find out if the StopWatch is started. A suspended StopWatch is also
* started watch.
*
*
* @return boolean If the StopWatch is started.
*/
abstract boolean isStarted();
/**
*
* This method is used to find out whether the 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.
*/
abstract boolean isStopped();
/**
*
* This method is used to find out whether the StopWatch is suspended.
*
*
* @return boolean If the StopWatch is suspended.
*/
abstract boolean isSuspended();
}
/**
* Enumeration type which indicates the split status of stopwatch.
*/
private enum SplitState {
SPLIT, UNSPLIT
}
/**
* 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.
*/
private long startTime;
/**
* The start time in Millis - nanoTime is only for elapsed time so we need to also store the
* currentTimeMillis to maintain the old getStartTime API.
*/
private long startTimeMillis;
/**
* The stop time.
*/
private long stopTime;
/**
* The stop time in Milis.
*/
private long stopTimeMillis;
/**
* Constructor.
*/
public StopWatch() {
this(true);
}
/**
* Constructor.
* @param start start the stopwatch
*/
public StopWatch(boolean start) {
if (start) {
start();
}
}
/**
*
* Start the stopwatch.
*
*
* This method starts a new timing session, clearing any previous values.
*
*
* @return this
* @throws IllegalStateException if the StopWatch is already running.
*/
public StopWatch 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.startTime = System.nanoTime();
this.startTimeMillis = System.currentTimeMillis();
this.runningState = State.RUNNING;
return this;
}
/**
*
* Stop the stopwatch.
*
*
* This method ends a new timing session, allowing the time to be retrieved.
*
*
* @return this
* @throws IllegalStateException if the StopWatch is not running.
*/
public StopWatch stop() {
if (this.runningState != State.RUNNING && this.runningState != State.SUSPENDED) {
throw new IllegalStateException("Stopwatch is not running. ");
}
if (this.runningState == State.RUNNING) {
this.stopTime = System.nanoTime();
this.stopTimeMillis = System.currentTimeMillis();
}
this.runningState = State.STOPPED;
return this;
}
/**
*
* Resets the stopwatch. Stops it if need be.
*
*
* This method clears the internal values to allow the object to be reused.
*
* @return this
*/
public StopWatch reset() {
this.runningState = State.UNSTARTED;
this.splitState = SplitState.UNSPLIT;
return this;
}
/**
*
* Restarts the stopwatch.
*
* @return this
*/
public StopWatch restart() {
reset();
start();
return this;
}
/**
*
* Split the time.
*
*
* 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.
*
*
* @return this
* @throws IllegalStateException if the StopWatch is not running.
*/
public StopWatch split() {
if (this.runningState != State.RUNNING) {
throw new IllegalStateException("Stopwatch is not running. ");
}
this.stopTime = System.nanoTime();
this.stopTimeMillis = System.currentTimeMillis();
this.splitState = SplitState.SPLIT;
return this;
}
/**
*
* Remove a split.
*
*
* This method clears the stop time. The start time is unaffected, enabling timing from the
* original start point to continue.
*
*
* @return this
* @throws IllegalStateException if the StopWatch has not been split.
*/
public StopWatch unsplit() {
if (this.splitState != SplitState.SPLIT) {
throw new IllegalStateException("Stopwatch has not been split. ");
}
this.splitState = SplitState.UNSPLIT;
return this;
}
/**
*
* Suspend the stopwatch for later resumption.
*
*
* 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.
*
*
* @return this
* @throws IllegalStateException if the StopWatch is not currently running.
*/
public StopWatch suspend() {
if (this.runningState != State.RUNNING) {
throw new IllegalStateException("Stopwatch must be running to suspend. ");
}
this.stopTime = System.nanoTime();
this.stopTimeMillis = System.currentTimeMillis();
this.runningState = State.SUSPENDED;
return this;
}
/**
*
* Resume the stopwatch after a suspend.
*
*
* 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.
*
*
* @return this
* @throws IllegalStateException if the StopWatch has not been suspended.
*/
public StopWatch resume() {
if (this.runningState != State.SUSPENDED) {
throw new IllegalStateException("Stopwatch must be suspended to resume. ");
}
this.startTime += System.nanoTime() - this.stopTime;
this.startTimeMillis += System.currentTimeMillis() - this.stopTimeMillis;
this.runningState = State.RUNNING;
return this;
}
/**
*
* Get the time on the stopwatch.
*
*
* This is either the time between the start and the moment this method is called, or the amount
* of time between start and stop.
*
*
* @return the time in milliseconds
*/
public long getTime() {
if (this.runningState == State.STOPPED || this.runningState == State.SUSPENDED) {
return this.stopTimeMillis - this.startTimeMillis;
}
else if (this.runningState == State.UNSTARTED) {
return 0;
}
else if (this.runningState == State.RUNNING) {
return System.currentTimeMillis() - this.startTimeMillis;
}
throw new RuntimeException("Illegal running state has occured. ");
}
/**
*
* Get the time on the stopwatch in nanoseconds.
*
*
* This is either the time between the start and the moment this method is called, or the amount
* of time between start and stop.
*
*
* @return the time in nanoseconds
*/
public long getNanoTime() {
if (this.runningState == State.STOPPED || this.runningState == State.SUSPENDED) {
return this.stopTime - this.startTime;
}
else if (this.runningState == State.UNSTARTED) {
return 0;
}
else if (this.runningState == State.RUNNING) {
return System.nanoTime() - this.startTime;
}
throw new RuntimeException("Illegal running state has occured. ");
}
/**
*
* Get the split time on the stopwatch.
*
*
* This is the time between start and latest split.
*
*
* @return the split time in milliseconds
* @throws IllegalStateException if the StopWatch has not yet been split.
*/
public long getSplitTime() {
if (this.splitState != SplitState.SPLIT) {
throw new IllegalStateException("Stopwatch must be split to get the split time. ");
}
return this.stopTimeMillis - this.startTimeMillis;
}
/**
*
* Get the split time on the stopwatch in nanoseconds.
*
*
* This is the time between start and latest split.
*
*
* @return the split time in nanoseconds
* @throws IllegalStateException if the StopWatch has not yet been split.
*/
public long getSplitNanoTime() {
if (this.splitState != SplitState.SPLIT) {
throw new IllegalStateException("Stopwatch must be split to get the split time. ");
}
return this.stopTime - this.startTime;
}
/**
* Returns the time this stopwatch was started.
*
* @return the time this stopwatch was started
* @throws IllegalStateException if this StopWatch has not been started
*/
public long getStartTime() {
if (this.runningState == State.UNSTARTED) {
throw new IllegalStateException("Stopwatch has not been started");
}
return this.startTimeMillis;
}
/**
* Returns the time this stopwatch was started.
*
* @return the time this stopwatch was started
* @throws IllegalStateException if this StopWatch has not been started
*/
public long getStartNanoTime() {
if (this.runningState == State.UNSTARTED) {
throw new IllegalStateException("Stopwatch has not been started");
}
return this.startTime;
}
/**
* Returns the time this stopwatch was stopped or suspended.
*
* @return the time this stopwatch was stopped or suspended
* @throws IllegalStateException if this StopWatch has not been stopped or suspended
*/
public long getStopTime() {
if (this.runningState != State.STOPPED && this.runningState != State.SUSPENDED) {
throw new IllegalStateException("Stopwatch must be stopped or suspended to get the stop time. ");
}
return this.stopTimeMillis;
}
/**
* Returns the time this stopwatch was stopped or suspended.
*
* @return the time this stopwatch was stopped or suspended
* @throws IllegalStateException if this StopWatch has not been stopped or suspended
*/
public long getStopNanoTime() {
if (this.runningState != State.STOPPED || this.runningState != State.SUSPENDED) {
throw new IllegalStateException("Stopwatch must be stopped or suspended to get the stop time. ");
}
return this.stopTime;
}
/**
*
* Gets a summary of the time that the stopwatch recorded as a string.
*
*
* @return the time as a String
*/
@Override
public String toString() {
return TimeSpan.toDisplayString(getTime());
}
/**
*
* Gets a summary of the split time that the stopwatch recorded as a string.
*
*
* @return the split time as a String
*/
public String toSplitString() {
return TimeSpan.toDisplayString(getSplitTime());
}
/**
*
* The method is used to find out if the StopWatch is started. A suspended StopWatch is also
* started watch.
*
*
* @return boolean If the StopWatch is started.
*/
public boolean isStarted() {
return runningState.isStarted();
}
/**
*
* This method is used to find out whether the StopWatch is suspended.
*
*
* @return boolean If the StopWatch is suspended.
*/
public boolean isSuspended() {
return runningState.isSuspended();
}
/**
*
* This method is used to find out whether the 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.
*/
public boolean isStopped() {
return runningState.isStopped();
}
public static StopWatch run(Runnable r) {
StopWatch sw = new StopWatch();
r.run();
sw.stop();
return sw;
}
}