javax.realtime
Class ProcessingGroupParameters

java.lang.Object
  javax.realtime.ProcessingGroupParameters

public class ProcessingGroupParameters

extends java.lang.Object

This is associated with one or more schedulable objects for which the system guarantees that the associated objects will not be given more time per period than indicated by cost. On implementations which do not support processing group parameters, this class may be used as a hint to the feasibility algorithm. The motivation for this class is to allow the execution demands of one or more aperiodic schedulable objects to be bound so that they can be included in feasibility analysis. However, periodic or sporadic schedulable objects can also be associated with a processing group.

For all schedulable objects with a reference to an instance of PhysicalMemoryTypeFilter p no more than p.cost will be allocated to the execution of these schedulable objects in each interval of time given by p.period after the time indicated by p.start. Logically a virtual server is associated with each instance of ProcessingGroupParameters. This server has a start time, a period, a cost (budget) and a deadline. The server can only logically execute when (a) it has not consumed more execution time in its current release than the cost (budget) parameter, (b) one of its associated schedulable objects is executable and is the most eligible of the executable schedulable objects. If the server is logically executable, the associated schedulable object is executed. When the cost has been consumed, any overrunHandler is released, and the server is not eligible for logical execution until its next period is due. At this point, its allocated cost (budget) is replenished. If the server is logically executing when its deadline expires, any associated missHandler is released. The deadline and cost parameters of all the associated schedulable objects have the same impact as they would if the objects were not bound to a processing group.

Processing group parameters use HighResolutionTime values for cost, deadline, period and start time. Since those times are expressed as a HighResolutionTime, the values use accurate timers with nanosecond granularity. The actual resolution available and even the quantity it measures depends on the clock associated with each time value.

When a reference to a ProcessingGroupParameters object is given as a parameter to a schedulable object's constructor or passed as an argument to one of the schedulable object's setter methods, the ProcessingGroupParameters object becomes the processing group parameters object bound to that schedulable object. Changes to the values in the ProcessingGroupParameters object affect that schedulable object. If bound to more than one schedulable object then changes to the values in the ProcessingGroupParameters object affect all of the associated objects. Note that this is a one-to-many relationship and not a many-to-many.

The implementation must use modified copy semantics for each HighResolutionTime parameter value. The value of each time object should be treated as if it were copied at the time it is passed to the parameter object, but the object reference must also be retained. Only changes to a ProcessingGroupParameters object caused by methods on that object are immediately visible to the scheduler. For instance, invoking setPeriod() on a ProcessingGroupParameters object will make the change, then notify that the scheduler that the parameter object has changed. At that point the scheduler's view of the processing group parameters object is updated. Invoking a method on the RelativeTime object that is the period for this object may change the period but it does not pass the change to the scheduler at that time. That new value for period must not change the behavior of the SOs that use the parameter object until a setter method on the ProcessingGroupParameters object is invoked, or the parameter object is used in setProcessingGroupParameters() or a constructor for an SO.

The implementation may use copy semantics for each HighResolutionTime parameter value. For instance the value returned by getCost() must be equal to the value passed in by setCost, but it need not be the same object.

Caution: This class is explicitly unsafe in multithreaded situations when it is being changed. No synchronization is done. It is assumed that users of this class who are mutating instances will be doing their own synchronization at a higher level.

Caution: The cost parameter time should be considered to be measured against the target platform.

Field Summary

protected RelativeTime	cost
protected RelativeTime	deadline
protected AsyncEventHandler	missHandler
protected AsyncEventHandler	overrunHandler
protected HighResolutionTime	period
protected HighResolutionTime	start

Constructor Summary

ProcessingGroupParameters(HighResolutionTime start, HighResolutionTime period, RelativeTime cost, RelativeTime deadline, AsyncEventHandler overrunHandler, AsyncEventHandler missHandler)
Constructor.

Method Summary

RelativeTime	getCost()
AsyncEventHandler	getCostOverrunHandler()
RelativeTime	getDeadline()
AsyncEventHandler	getDeadlineMissHandler()
HighResolutionTime	getPeriod()
HighResolutionTime	getStart()
void	setCost(RelativeTime cost)
void	setCostOverrunHandler(AsyncEventHandler overrunHandler)
void	setDeadline(RelativeTime deadline)
void	setDeadlineMissHandler(AsyncEventHandler missHandler)
boolean	setIfFeasible(RelativeTime period, RelativeTime cost, RelativeTime deadline) Not currently implemented
void	setPeriod(RelativeTime period)
void	setStart(HighResolutionTime start)

Methods inherited from class java.lang.Object

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

Field Detail

start

protected HighResolutionTime start

period

protected HighResolutionTime period

cost

protected RelativeTime cost

deadline

protected RelativeTime deadline

overrunHandler

protected AsyncEventHandler overrunHandler

missHandler

protected AsyncEventHandler missHandler

Constructor Detail

ProcessingGroupParameters

public ProcessingGroupParameters(HighResolutionTime start,
                                 HighResolutionTime period,
                                 RelativeTime cost,
                                 RelativeTime deadline,
                                 AsyncEventHandler overrunHandler,
                                 AsyncEventHandler missHandler)

Constructor.

Parameters:

start -

period -

cost -

deadline -

overrunHandler -

missHandler -

Method Detail

getCost

public RelativeTime getCost()

Returns:

the cost of this

getCostOverrunHandler

public AsyncEventHandler getCostOverrunHandler()

Returns:

the cost overrun handler of this

getDeadline

public RelativeTime getDeadline()

Returns:

the deadline of this

getDeadlineMissHandler

public AsyncEventHandler getDeadlineMissHandler()

Returns:

the deadline miss handler of this

getPeriod

public HighResolutionTime getPeriod()

Returns:

the period of this

getStart

public HighResolutionTime getStart()

Returns:

the start time of this

setCost

public void setCost(RelativeTime cost)

Parameters:

cost -

setCostOverrunHandler

public void setCostOverrunHandler(AsyncEventHandler overrunHandler)

Parameters:

overrunHandler -

setDeadline

public void setDeadline(RelativeTime deadline)

Parameters:

deadline -

setDeadlineMissHandler

public void setDeadlineMissHandler(AsyncEventHandler missHandler)

Parameters:

missHandler -

setIfFeasible

public boolean setIfFeasible(RelativeTime period,
                             RelativeTime cost,
                             RelativeTime deadline)

Not currently implemented

Parameters:

period -

cost -

deadline -

Returns:

true if the resulting system is feasible

setPeriod

public void setPeriod(RelativeTime period)

Parameters:

period -

setStart

public void setStart(HighResolutionTime start)

Parameters:

start -