javax.realtime

Class FirstInFirstOutScheduler

java.lang.Object

javax.realtime.Scheduler

javax.realtime.PriorityScheduler

javax.realtime.FirstInFirstOutScheduler

public class FirstInFirstOutScheduler
extends PriorityScheduler

A version of PriorityScheduler where once a thread is scheduled at a given priority, it runs until it is blocked or is preempted by a higher priority thread. When preempted, it remains the next thread ready for its priority. This is the default scheduler for realtime tasks. It represents the required (by the RTSJ) priority-based scheduler. The default instance is the base scheduler which does fixed priority, preemptive scheduling.

This scheduler, like all schedulers, governs the default values for scheduling-related parameters in its client schedulables. The defaults are as follows:

FirstInFirstOut Default PriorityParameter Values

Attribute	Default Value
Priority	norm priority

The system contains one instance of the FirstInFirstOutScheduler which is the system's base scheduler and is returned by FirstInFirstOutScheduler.instance(). The instance returned by the instance() method is the base scheduler and is returned by Scheduler.getDefaultScheduler() unless the default scheduler is reset with Scheduler.setDefaultScheduler(Scheduler).

Since:

RTSJ 2.0

Field Summary

Fields inherited from class javax.realtime.PriorityScheduler

MAX_PRIORITY, MIN_PRIORITY

Method Summary

Modifier and Type	Method and Description
int	getMaxPriority() Obtains the maximum priority available for a schedulable managed by this scheduler.
int	getMinPriority() Obtains the minimum priority available for a schedulable managed by this scheduler.
int	getNormPriority() Obtains the normal priority available for a schedulable managed by this scheduler.
java.lang.String	getPolicyName() Obtains the policy name of this.
static FirstInFirstOutScheduler	instance() Obtains a reference to the distinguished instance of PriorityScheduler which is the system's base scheduler.
void	reschedule(java.lang.Thread thread, SchedulingParameters eligibility) Promotes a java.lang.Thread to realtime priority under this scheduler.

Methods inherited from class javax.realtime.PriorityScheduler

addToFeasibility, createDefaultSchedulingParameters, fireSchedulable, getMaxPriority, getMinPriority, getNormPriority, isFeasible, removeFromFeasibility, setIfFeasible, setIfFeasible, setIfFeasible

Methods inherited from class javax.realtime.Scheduler

currentSchedulable, getDefaultScheduler, inSchedulableExecutionContext, setDefaultScheduler

Methods inherited from class java.lang.Object

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

Method Detail

instance

public static FirstInFirstOutScheduler instance()

Obtains a reference to the distinguished instance of PriorityScheduler which is the system's base scheduler.

Returns:

a reference to the distinguished instance PriorityScheduler.

getMaxPriority

public int getMaxPriority()

Obtains the maximum priority available for a schedulable managed by this scheduler.

Overrides:

getMaxPriority in class PriorityScheduler

Returns:

the value of the maximum priority.

getMinPriority

public int getMinPriority()

Obtains the minimum priority available for a schedulable managed by this scheduler.

Overrides:

getMinPriority in class PriorityScheduler

Returns:

the minimum priority used by this scheduler.

getNormPriority

public int getNormPriority()

Obtains the normal priority available for a schedulable managed by this scheduler.

Overrides:

getNormPriority in class PriorityScheduler

Returns:

the value of the normal priority.

getPolicyName

public java.lang.String getPolicyName()

Obtains the policy name of this.

Overrides:

getPolicyName in class PriorityScheduler

Returns:

the policy name (Fixed Priority First In First Out) as a string.

reschedule

public void reschedule(java.lang.Thread thread,
                       SchedulingParameters eligibility)

Description copied from class: Scheduler

Promotes a java.lang.Thread to realtime priority under this scheduler. The affected thread will be scheduled as if it was a RealtimeThread with the given eligibility. This does not make the affected thread a RealtimeThread, however, and it will not have access to facilities reserved for instances of RealtimeThread. Instances of RealtimeThread will be treated as if their scheduling parameters were set to eligibility.

Overrides:

reschedule in class PriorityScheduler

Parameters:

thread - The thread to promote to realtime scheduling.

eligibility - A SchedulingParameters instance such as PriorityParameters for a PriorityScheduler.