org.mindswap.pellet.utils
Class Timer

java.lang.Object
  extended by org.mindswap.pellet.utils.Timer

public class Timer
extends java.lang.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 dependancy 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 dependant timer may expire. To handle such cases, a timer may be asscoaited with a dependant timer so every time a timer is checked for a timeout, its dependant timer will also be checked. Normally, we would like to associate many dependants with a timer but for efficency reasons (looping over an array each time is expensive) each timer is allowed to have only one dependant.

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

Author:
Evren Sirin
See Also:
Timers

Field Summary
static long NO_TIMEOUT
           
static long NOT_STARTED
           
 
Constructor Summary
Timer(java.lang.String name)
          Create a timer with no dependant.
Timer(java.lang.String name, Timer dependant)
          Create a timer that has the specified dependant timer.
 
Method Summary
 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.
 double getAverage()
          Retutn 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 miliseconds) since the last time this timer was started.
 long getLast()
          Return the total time spent between last start()-stop() period.
 java.lang.String getName()
          Return the name of this timer.
 long getTimeout()
          Return the timeout associated with this timer.
 long getTotal()
          Return the total time (in miliseconds) spent while this timer was running.
 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 counters associated with this timer.
 void setTimeout(long timeout)
          Set a timeout limit for this timer.
 void start()
          Start time timer by recording the time this function is called.
 void stop()
          Stop the timer, increment the count and update the total time spent.
 java.lang.String toString()
           
 
Methods inherited from class java.lang.Object
equals, 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(java.lang.String name)
Create a timer with no dependant.

Parameters:
name -

Timer

public Timer(java.lang.String name,
             Timer dependant)
Create a timer that has the specified dependant timer.

Parameters:
name -
dependant -
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 void 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.


reset

public void reset()
Reset all the counters associated with this timer. After this function call it will be like timer has never been used.


check

public void check()
           throws TimeoutException
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

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 java.lang.String getName()
Return the name of this timer.

Returns:

getElapsed

public long getElapsed()
Return the time elapsed (in miliseconds) 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 miliseconds) 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 onyl 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()
Retutn 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 diable timeout checking

Parameters:
timeout -

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object


Copyright © 2007-2009 Natalya Keberle. All Rights Reserved.