se.lth.cs.realtime
Class SporadicThread

java.lang.Object
  se.lth.cs.realtime.RTThread
      se.lth.cs.realtime.CyclicThread
          se.lth.cs.realtime.SporadicThread

All Implemented Interfaces:

Activity, java.util.EventListener, RTEventListener, RTEventSource, java.lang.Runnable

public class SporadicThread

extends CyclicThread

This class models a real-time thread that executes the same function every time it is triggered.

The execution frequency must be upper-bound specifying a shortest period for this thread(if FixedPeriod is implemented, the shortest period can be modified only before this thread is started).

Being a CyclicThread, a SporadicThread may be suspended and resumed by other threads. By default, the "triggering events" that occur during the suspension time are served after the resumption.

See Also:

License

Field Summary

protected int

failedTriggerCount

Fields inherited from class se.lth.cs.realtime.CyclicThread

suspendLock

Fields inherited from class se.lth.cs.realtime.RTThread

defaultBufferSize, dispatcher, mailbox, MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

SporadicThread(long shortestPeriod)
Allocates a new SporadicThread object.

SporadicThread(RTThreadGroup group, long shortestPeriod)
Allocates a new SporadicThread object.

SporadicThread(RTThreadGroup group, java.lang.String name, long shortestPeriod)
Allocates a new SporadicThread object.

SporadicThread(java.lang.String name, long shortestPeriod)
Allocates a new SporadicThread object.

Method Summary

long	getShortestPeriod() Returns the shortest period of this thread, in milliseconds.
protected void	perform() Does nothing.
void	setShortestPeriod(long shortestPeriod) Sets the shortest period of this thread, in milliseconds.
java.lang.String	toString() Returns a string representation of this thread, including the thread's name, priority and shortest period in milliseconds.
int	trigger() Causes the execution of the perform method.
protected void	waitToPerform() Lets this thread wait for a call to the function trigger.

Methods inherited from class se.lth.cs.realtime.CyclicThread

isSuspended, onResuming, resume, run, stop, suspend

Methods inherited from class se.lth.cs.realtime.RTThread

addListener, currentRTThread, currentThread, dumpStack, getDispatcher, getEnv, getMaxTimeLag, getName, getPriority, getRTThreadId, getThreadGroup, getTimebase, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, putEvent, setDaemon, setMaxTimeLag, setName, setPriority, sleep, sleep, sleepUntil, start, terminate, yield

Methods inherited from class java.lang.Object

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

Field Detail

failedTriggerCount

protected volatile int failedTriggerCount

Constructor Detail

SporadicThread

public SporadicThread(long shortestPeriod)

Allocates a new SporadicThread object.

Equivalent to SporadicThread(null, null, true, shortestPeriod).

Parameters:

shortestPeriod - the shortest period of the new thread, in milliseconds.

Throws:

java.lang.IllegalArgumentException - if the shortest period is not positive.

See Also:

SporadicThread(RTThreadGroup,java.lang.String,long)

SporadicThread

public SporadicThread(RTThreadGroup group,
                      long shortestPeriod)

Allocates a new SporadicThread object.

Equivalent to SporadicThread(group, null, true, shortestPeriod).

Parameters:

group - this thread's RTThreadGroup..

shortestPeriod - the shortest period of the new thread, in milliseconds.

Throws:

java.lang.IllegalArgumentException - if the shortest period is not positive.

See Also:

SporadicThread(RTThreadGroup, java.lang.String, long)

SporadicThread

public SporadicThread(RTThreadGroup group,
                      java.lang.String name,
                      long shortestPeriod)

Allocates a new SporadicThread object.

Equivalent to SporadicThread(group, name, true, shortestPeriod).

Parameters:

name - the name of the new thread.

group - this thread's RTThreadGroup..

shortestPeriod - the shortest period of the new thread, in milliseconds.

Throws:

java.lang.IllegalArgumentException - if the shortest period is not positive.

See Also:

SporadicThread(RTThreadGroup, java.lang.String, long)

SporadicThread

public SporadicThread(java.lang.String name,
                      long shortestPeriod)

Allocates a new SporadicThread object.

Equivalent to SporadicThread(null, name, true, shortestPeriod).

Parameters:

name - the name of the new thread.

shortestPeriod - the shortest period of the new thread, in milliseconds.

Throws:

java.lang.IllegalArgumentException - if the shortest period is not positive.

See Also:

SporadicThread(RTThreadGroup,java.lang.String,long)

Method Detail

getShortestPeriod

public long getShortestPeriod()

Returns the shortest period of this thread, in milliseconds.

Returns:

the shortest period in ms.

perform

protected void perform()

Does nothing. This empty implementation allows the use of a SporadicThread as a TriggerEvent generator only.

Specified by:

perform in class CyclicThread

See Also:

TriggerEvent

setShortestPeriod

public void setShortestPeriod(long shortestPeriod)
                       throws FixedPeriodError

Sets the shortest period of this thread, in milliseconds. If this thread implements FixedPeriodand is alive , an exception is thrown.

Parameters:

shortestPeriod - the new shortest period of this thread.

Throws:

java.lang.IllegalArgumentException - if the argument is not positive.

FixedPeriodError - if the thread is alive and implements FixedPeriod.

toString

public java.lang.String toString()

Returns a string representation of this thread, including the thread's name, priority and shortest period in milliseconds.

Overrides:

toString in class CyclicThread

Returns:

a string representation of this thread.

trigger

public int trigger()

Causes the execution of the perform method. Each SporadicThread can have at most one triggering thread. The first RTThread which tries to trigger this thread will be the triggering thread.

Returns:

-2 - This thread isn't alive to be triggered.

waitToPerform

protected void waitToPerform()
                      throws java.lang.InterruptedException

Lets this thread wait for a call to the function trigger.

Specified by:

waitToPerform in class CyclicThread

Throws:

java.lang.InterruptedException - if another thread has interrupted this one.