javax.realtime

Class SporadicParameters

java.lang.Object

javax.realtime.ReleaseParameters<AperiodicParameters>

javax.realtime.AperiodicParameters

javax.realtime.SporadicParameters

All Implemented Interfaces:

Serializable, Cloneable

public class SporadicParameters
extends AperiodicParameters
implements Cloneable

Jamaica Real-Time Specification for Java class SporadicParameters.

This class characterizes the release of schedulable objects that can be released at any time but with a minimum time between two releases. Unlike AperiodicParameters, SporadicParameters does not necessarily make the feasibility analysis of a set of schedulable objects impossible.

Note that any changes to RelativeTime arguments of this object do not propagate to the schedulable object until the corresponding setter method of AperiodicParameters is called to notify this object about the change.

NOTE: the methods in this class are not synchronized. They cannot be used by several threads simultaneously without proper explicit synchronization.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	mitViolationExcept Deprecated. RTSJ V2.0
static String	mitViolationIgnore Deprecated. RTSJ V2.0
static String	mitViolationReplace Deprecated. RTSJ V2.0
static String	mitViolationSave Deprecated. RTSJ V2.0

Fields inherited from class javax.realtime.AperiodicParameters

arrivalTimeQueueOverflowExcept, arrivalTimeQueueOverflowIgnore, arrivalTimeQueueOverflowReplace, arrivalTimeQueueOverflowSave

Fields inherited from class javax.realtime.ReleaseParameters

DISABLE_MONITORING

Constructor Summary

Constructors

Constructor and Description
SporadicParameters(RelativeTime minInterarrival) Create a SporadicParameters object.
SporadicParameters(RelativeTime minInterarrival, RelativeTime cost, AsyncEventHandler overrunhandler, boolean rousable) Equivalent to SporadicParameters(RelativeTime, RelativeTime, RelativeTime, AsyncEventHandler, AsyncEventHandler, boolean) with an argument list of (minInterarrival, null, deadline, null, missHandler, rousable).
SporadicParameters(RelativeTime minInterarrival, RelativeTime cost, RelativeTime deadline, AsyncEventHandler overrunHandler, AsyncEventHandler missHandler) Constructor of SporadicParameters to be used as ReleaseParameters for AsyncBaseEventHandler if the event handler will be scheduled aperiodically with a miminum interarrival time between each two releases.
SporadicParameters(RelativeTime minInterarrival, RelativeTime cost, RelativeTime deadline, AsyncEventHandler overrunHandler, AsyncEventHandler missHandler, boolean rousable) Creates a SporadicParameters object.

Method Summary

Modifier and Type	Method and Description
Object	clone() clone creates a clone of this object with the same parameters but without association to any schedulable object.
RelativeTime	getMinimumInterarrival() Determines the current value of minimal interarrival.
RelativeTime	getMinimumInterarrival(RelativeTime value) Determines the current value of minimum interarrival.
MinimumInterarrivalPolicy	getMinimumInterarrivalPolicy() Gets the arrival time queue policy for handling minimal interarrival time underflow.
String	getMitViolationBehavior() Deprecated. as of RTSJ 2.0
boolean	setIfFeasible(RelativeTime cost, RelativeTime deadline) Deprecated. as of RTSJ 2.0, because the framework for feasibility analysis is inadequate.
boolean	setIfFeasible(RelativeTime interarrival, RelativeTime cost, RelativeTime deadline) Deprecated. as of RTSJ 2.0, because the framework for feasibility analysis is inadequate.
SporadicParameters	setMinimumInterarrival(RelativeTime interarrival) setMinimumInterarrival sets the minimum interarrival time to a new value, independent on the impact this will have on the feasibility of the system.
SporadicParameters	setMinimumInterarrivalPolicy(MinimumInterarrivalPolicy policy) Sets the policy for handling the arrival time queue when the new arrival time is closer to the previous arrival time than the minimum interarrival time given in this.
void	setMitViolationBehavior(String behavior) Deprecated. as of RTSJ 2.0

Methods inherited from class javax.realtime.AperiodicParameters

getArrivalTimeQueueOverflowBehavior, getInitialArrivalTimeQueueLength, setArrivalTimeQueueOverflowBehavior, setInitialArrivalTimeQueueLength

Methods inherited from class javax.realtime.ReleaseParameters

getCost, getCost, getCostOverrunHandler, getDeadline, getDeadline, getDeadlineMissHandler, getEventQueueOverflowPolicy, getInitialQueueLength, isRousable, setCost, setCostOverrunHandler, setDeadline, setDeadlineMissHandler, setEventQueueOverflowPolicy, setInitialQueueLength, setRousable

Methods inherited from class java.lang.Object

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

Field Detail

mitViolationExcept

@Deprecated
public static final String mitViolationExcept

Deprecated. RTSJ V2.0

The "EXCEPT" policy for dealing with minimum arrival time violations. Throws a MITViolationException on a call to fire() when the arrival time occurs earlier than the minimum interarrival time since the last release.

mitViolationIgnore

@Deprecated
public static final String mitViolationIgnore

Deprecated. RTSJ V2.0

The "IGNORE" policy for dealing with minimum arrival time violations. If a call to fire() before the minimum interarrival time time occurs, then the new release is ignored.

mitViolationReplace

@Deprecated
public static final String mitViolationReplace

Deprecated. RTSJ V2.0

The "REPLACE" policy for dealing with minimum arrival time violations. If a call to fire() before the minimum interarrival time time occurs, then the new release replaces a previous release.

mitViolationSave

@Deprecated
public static final String mitViolationSave

Deprecated. RTSJ V2.0

The "SAVE" policy for dealing with minimum arrival time violations. When this policy is used, there will be no checks for correct minimum interarrival times for incoming releases.

Constructor Detail

SporadicParameters

public SporadicParameters(RelativeTime minInterarrival)

Create a SporadicParameters object. This constructor is equivalent to SporadicParameters(minInterarrival, null, null, null, null).

SporadicParameters

public SporadicParameters(RelativeTime minInterarrival,
                          RelativeTime cost,
                          AsyncEventHandler overrunhandler,
                          boolean rousable)

Equivalent to SporadicParameters(RelativeTime, RelativeTime, RelativeTime, AsyncEventHandler, AsyncEventHandler, boolean) with an argument list of (minInterarrival, null, deadline, null, missHandler, rousable).

Since:

RTSJ 2.0

SporadicParameters

public SporadicParameters(RelativeTime minInterarrival,
                          RelativeTime cost,
                          RelativeTime deadline,
                          AsyncEventHandler overrunHandler,
                          AsyncEventHandler missHandler,
                          boolean rousable)

Creates a SporadicParameters object.

Throws:

StaticIllegalArgumentException - when minInterarrival is null or its time value is not greater than zero, or the time value of cost is less than zero, or the time value of deadline is not greater than zero, or when the chronograph associated with deadline and minInterarrival parameters are not identical or not an instance of Clock.

IllegalAssignmentError - when minInterarrival, cost, deadline, overrunHandler or missHandler cannot be stored in this.

Parameters:

minInterarrival - The release times of the schedulable will occur no closer than this interval. This time object is treated as if it were copied. Changes to minInterarrival will not affect the SporadicParameters object. There is no default value. When minInterarrival is null an illegal argument exception is thrown.

cost - Processing time per release. On implementations which can measure the amount of time a schedulable is executed, this value is the maximum amount of time a schedulable receives per release. When null, the default value is a new instance of RelativeTime(0,0).

deadline - The latest permissible completion time measured from the release time of the associated invocation of the schedulable. When null, the default value is a new instance of minInterarrival: new RelativeTime(minInterarrival).

overrunHandler - This handler is invoked when an invocation of the schedulable exceeds cost. Not required for minimum implementation. When null no overrun handler will be used.

missHandler - This handler is invoked when the run() method of the schedulable is still executing after the deadline has passed. When null, no deadline miss handler will be used.

rousable - Determines whether or not an instance of Schedulable can be prematurely released by a thread interrupt.

Since:

RTSJ 2.0

SporadicParameters

public SporadicParameters(RelativeTime minInterarrival,
                          RelativeTime cost,
                          RelativeTime deadline,
                          AsyncEventHandler overrunHandler,
                          AsyncEventHandler missHandler)

Constructor of SporadicParameters to be used as ReleaseParameters for AsyncBaseEventHandler if the event handler will be scheduled aperiodically with a miminum interarrival time between each two releases.

Throws:

StaticIllegalArgumentException - if the interarrival is null or negative or zero, if cost is negative or deadline is negative or zero.

Parameters:

minInterarrival - The minimum interarrival time for two successive releases of an associated schedulable object. This parameter will be copied, changes to its value will have no effect on this SporadicParameters once the SporadicParameters object has been created.

cost - The CPU time required for each release. If cost monitoring is performed, this gives the maximum amount of CPU time that will be allowed for each release. In any case, this may be used by the feasibility analysis. If null, the default value will be new RelativeTime(0, 0). Note that on a system with cost monitoring, this default value will allow no execution time for the associated schedulable object.

deadline - The deadline for the completion of one release, relative to the release time of that release. When null, the default value is a new instance of RelativeTime(0,0).

overrunHandler - This handler will be invoked if the cost of one invocation exceeds the cost parameter. If null, there will be no overrunHandler.

For JamaicaVM, cost overrun checking is enabled if CpuTime.CPU_TIME_SUPPORTED is true. The accuracy of the cost enforcement can be specified in nanoseconds via the property jamaica.cost_monitoring_accuracy. The default value is 5000000, i.e., 5milliseconds.

missHandler - This handler will be invoked if the deadline of one release is missed. If null, there will be no deadline.

Method Detail

setIfFeasible

@Deprecated
public boolean setIfFeasible(RelativeTime cost,
                                         RelativeTime deadline)

Deprecated. as of RTSJ 2.0, because the framework for feasibility analysis is inadequate.

This method first performs a feasibility analysis using the new cost, and deadline as replacements for the matching attributes of this. When the resulting system is feasible, the method replaces the current scheduling characteristics, of this with the new scheduling characteristics.

Overrides:

setIfFeasible in class AperiodicParameters

Throws:

StaticIllegalArgumentException - when the time value of cost is less than zero, or the time value of deadline is less than or equal to zero, or the values are incompatible with the scheduler for any of the schedulables which are presently using this parameter object.

IllegalAssignmentError - when cost or deadline cannot be stored in this.

Parameters:

cost - The proposed cost used to determine when any particular object exceeds cost. When null, the default value is a new instance of RelativeTime(0,0).

deadline - The proposed deadline. When null, the default value is a new instance of RelativeTime(mit).

Returns:

true, when the resulting system is feasible and the changes are made; false, when the resulting system is not feasible and no changes are made.

setIfFeasible

@Deprecated
public boolean setIfFeasible(RelativeTime interarrival,
                                         RelativeTime cost,
                                         RelativeTime deadline)

Deprecated. as of RTSJ 2.0, because the framework for feasibility analysis is inadequate.

setIfFeasible performs a feasibility analysis using the new period, cost and deadline parameters. If the resulting system remains feasible, the period, cost and deadline will be set to the new values. This will change the corresponding attributes of all schedulable objects this is associated with.

Throws:

StaticIllegalArgumentException - if the interarrival is null or negative or zero, if cost is negative or deadline is negative or zero.

Parameters:

interarrival - The minimum interarrival time for two successive releases of an associated schedulable object. This parameter will be copied, changes to its value will have no effect on this SporadicParameters once the SporadicParameters object has been created.

cost - The CPU time required for each release. If cost monitoring is performed, this gives the maximum amount of CPU time that will be allowed for each release. In any case, this may be used by the feasibility analysis. If null, the default value will be new RelativeTime(0, 0). Note that on a system with cost monitoring, this default value will allow no execution time for the associated schedulable object.

deadline - The deadline for the completion of one release, relative to the release time of that release. If null, the default value is a new instance of RealtiveTime(Long.MAX_VALUE, 999999).

Returns:

true if the change was performed and the resulting system is feasible. false if the change would result in an infeasible system and was not performed.

getMinimumInterarrival

public RelativeTime getMinimumInterarrival()

Determines the current value of minimal interarrival.

Returns:

the object last used to set the minimal interarrival containing the current value of minimal interarrival. It is never null, always greater than zero.

getMinimumInterarrival

public RelativeTime getMinimumInterarrival(RelativeTime value)

Determines the current value of minimum interarrival.

Parameters:

value - A relative time object to fill and return.

Returns:

value or, when null, the last object used to set the minimal interarrival, set to the current value of minimal interarrival.

Since:

RTSJ 2.0

setMinimumInterarrival

public SporadicParameters setMinimumInterarrival(RelativeTime interarrival)

setMinimumInterarrival sets the minimum interarrival time to a new value, independent on the impact this will have on the feasibility of the system.

Throws:

StaticIllegalArgumentException - if the interarrival is null or negative or zero.

Parameters:

interarrival - The minimum interarrival time for two successive releases of an associated schedulable object. This parameter will be copied, changes to its value will have no effect on this SporadicParameters once the SporadicParameters object has been created.

Since:

RTSJ 2.0 returns itself

setMinimumInterarrivalPolicy

public SporadicParameters setMinimumInterarrivalPolicy(MinimumInterarrivalPolicy policy)

Sets the policy for handling the arrival time queue when the new arrival time is closer to the previous arrival time than the minimum interarrival time given in this.

Parameters:

policy - The current policy for MIT violations.

Since:

RTSJ 2.0

getMinimumInterarrivalPolicy

public MinimumInterarrivalPolicy getMinimumInterarrivalPolicy()

Gets the arrival time queue policy for handling minimal interarrival time underflow.

Returns:

the minimum interarrival time violation behavior as a string.

Since:

RTSJ 2.0

getMitViolationBehavior

@Deprecated
public String getMitViolationBehavior()

Deprecated. as of RTSJ 2.0

getMitViolationBehavior returns the current setting of the policy for dealing with minimum arrival time violations.

Returns:

the current policy for dealing with minimum arrival time violations. result is one of mitViolationExcept, mitViolationIgnore, mitViolationReplace, or mitViolationSave.

setMitViolationBehavior

@Deprecated
public void setMitViolationBehavior(String behavior)

Deprecated. as of RTSJ 2.0

setMitViolationBehavior sets the policy for dealing with minimum arrival time violations.

Throws:

StaticIllegalArgumentException - if behavior is not one of the constants arrivalTimeQueueOverflowExcept, arrivalTimeQueueOverflowIgnore, arrivalTimeQueueOverflowReplace, arrivalTimeQueueOverflowSave.

Parameters:

behavior - one of mitViolationExcept, mitViolationIgnore, mitViolationReplace, or mitViolationSave.

clone

public Object clone()

clone creates a clone of this object with the same parameters but without association to any schedulable object. According to RTSJ 1.0.2, the cost, deadline, and interarrival time attributes are deep-copied, whereas the missHandler, overrunHandler, overflow, and mit-violation behavior attributes are only shallow-copied.

Overrides:

clone in class AperiodicParameters

Returns:

a new instance of ReleaseParameters with equal cost, deadline and interarrival time attributes and copied references of the overrunHandler, missHandler, overflow, and mit-violation behavior attributes.

Since:

RTSJ V1.0.1

See Also:

Cloneable