org.mindswap.pellet.utils

Class Timer

java.lang.Object

org.mindswap.pellet.utils.Timer

public class Timer
extends Object

Class used to keep track how much time is spent for a specific operation. Timers are primarily used to display info about performance. A timer is started at the beginning of a function and is stopped at the end of that function (special care needed when there are multiple return commands in a function because the status of unstopped timers is undefined). A timer also stores how many times the timer has been started so average time spent in a function can be computed.

When a timer is used in a recursive function it will typically be started multiple times. Timer class will only measure the time spent in the first call. This is done by counting how many times a timer is started and time spent is computed only when the number of stop() calls evens out the start() calls. It is the programmer's responsibility to make sure each start() is stopped by a stop() call.

Each timer may be associated with a timeout limit. This means that time spent between start() and stop() calls should be less than the timeout specified. Timeouts will only be checked when check() function is called. If check() function is not called setting timeouts has no effect. It is up to the programmer to decide when and how many times a timer will be checked.

There may be a dependency between timers. For example, classification, realization and entailment operations all use consistency checks. If something goes wrong inside a consistency check and that operation does not finish in a reasonable time, the timeout on the parent timer may expire. To handle such cases, a timer may be associated with a parent timer so every time a timer is checked for a timeout, its parent timer will also be checked. Normally, we would like to associate many parents with a timer but for efficiency reasons (looping over an array each time is expensive) each timer is allowed to have only one parent.

Timers class stores a set of timers and provides functions to start, stop and check timers.

Author:

Evren Sirin

See Also:

Timers

Field Summary

Fields

Modifier and Type	Field and Description
static long	NO_TIMEOUT
static long	NOT_STARTED

Constructor Summary

Constructors

Constructor and Description
Timer() Create a timer with no name and no parent.
Timer(String name) Create a timer with no parent.
Timer(String name, Timer parent) Create a timer that has the specified parent timer.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(Timer timer) Update the total time elapsed and number of counts by by adding the values from another timer.
void	check() Check if the elapsed time is greater than the timeout limit and throw a TimeoutException if that is the case.
String	format()
double	getAverage() Return the total time spent (in milliseconds) divided by the number of times this timer has been ran.
long	getCount() Return the total number of times this timer has been started and stopped.
long	getElapsed() Return the time elapsed (in milliseconds) since the last time this timer was started.
long	getLast() Return the total time spent between last start()-stop() period.
String	getName() Return the name of this timer.
Timer	getParent() Return the parent timer of this timer depends on.
long	getTimeout() Return the timeout associated with this timer.
long	getTotal() Return the total time (in milliseconds) spent while this timer was running.
void	interrupt() Interrupt timer so that the next check() call will throw an InterruptedException
boolean	isStarted() Return true if timer has been started with a start() call but not has been stopped with a stop() call.
void	reset() Reset all the internal counts associated with this timer.
void	restart() If started stop the timer and then start it again.
void	setTimeout(long timeout) Set a timeout limit for this timer.
void	start() Start time timer by recording the time this function is called.
long	stop() Stop the timer, increment the count and update the total time spent.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NOT_STARTED

public static final long NOT_STARTED

See Also:

Constant Field Values

NO_TIMEOUT

public static final long NO_TIMEOUT

See Also:

Constant Field Values

Constructor Detail

Timer

public Timer()

Create a timer with no name and no parent.

Timer

public Timer(String name)

Create a timer with no parent.

Parameters:

name -

Timer

public Timer(String name,
     Timer parent)

Create a timer that has the specified parent timer.

Parameters:

name -

parent -

Method Detail

add

public void add(Timer timer)

Update the total time elapsed and number of counts by by adding the values from another timer. This is especially useful if we are running

Parameters:

timer -

start

public void start()

Start time timer by recording the time this function is called. If timer is running when this function is called time is not recorded and only an internal counter is updated.

stop

public long stop()

Stop the timer, increment the count and update the total time spent. If timer has been started multiple times this function will only decrement the internal counter. Time information is updated only when all starts are evened out by stops.

Returns:

Return the total time spent after last start(), -1 if timer is still running, -Long.MAX_VALUE on error

reset

public void reset()

Reset all the internal counts associated with this timer. After this function call it will be like timer has never been used.

restart

public void restart()

If started stop the timer and then start it again.

check

public void check()
           throws TimeoutException,
                  TimerInterruptedException

Check if the elapsed time is greater than the timeout limit and throw a TimeoutException if that is the case. Check the parent timer if there is one.

Throws:

TimeoutException

TimerInterruptedException

interrupt

public void interrupt()

Interrupt timer so that the next check() call will throw an InterruptedException

isStarted

public boolean isStarted()

Return true if timer has been started with a start() call but not has been stopped with a stop() call.

Returns:

getName

public String getName()

Return the name of this timer.

Returns:

getElapsed

public long getElapsed()

Return the time elapsed (in milliseconds) since the last time this timer was started. If the timer is not running now 0 is returned.

Returns:

getTotal

public long getTotal()

Return the total time (in milliseconds) spent while this timer was running. If the timer is running when this function is called time elapsed will be discarded. Therefore, it is advised to use this function only with stopped timers.

Returns:

getCount

public long getCount()

Return the total number of times this timer has been started and stopped. Note that recursive start operations are computed only once so actual number of times start() function is called may be greater than this amount.

Returns:

getTimeout

public long getTimeout()

Return the timeout associated with this timer.

Returns:

getAverage

public double getAverage()

Return the total time spent (in milliseconds) divided by the number of times this timer has been ran. If the timer is still running elapsed time is discarded. Therefore, it is advised to use this function only with stopped timers.

Returns:

getLast

public long getLast()

Return the total time spent between last start()-stop() period.

Returns:

setTimeout

public void setTimeout(long timeout)

Set a timeout limit for this timer. Set the timeout to 0 to disable timeout checking

Parameters:

timeout -

toString

public String toString()

Overrides:

toString in class Object

getParent

public Timer getParent()

Return the parent timer of this timer depends on. Parent timers are checked hierarchically for timeouts.

Returns:

Parent timer or null if there is no such timer.

format

public String format()