javax.realtime

Class RealtimeThreadGroup

java.lang.Object

java.lang.ThreadGroup

javax.realtime.RealtimeThreadGroup

All Implemented Interfaces:

java.lang.Thread.UncaughtExceptionHandler

Direct Known Subclasses:

AsynchronousControlGroup

public class RealtimeThreadGroup
extends java.lang.ThreadGroup

An enhanced ThreadGroup in which a RealtimeThread instance may be started, as well as a convention Thread. Limits for what realtime scheduler and scheduling parameters can be enforced on all tasks in this group. A normal ThreadGroup may not contain an instance of Schedulable or instances of RealtimeThreadGroup. Every thread is in some instance of ThreadGroup and every instance of RealtimeThread is in some instance of RealtimeThreadGroup. This means that the main thread of a realtime Java implementation must be in an instance of this class, not a normal ThreadGroup.

Since:

RTSJ 2.0

Caution: This class is explicitly unsafe for multithreading when being changed. Code that mutates instances of this class should synchronize at a higher level.

Constructor Summary

Constructors

Constructor and Description
RealtimeThreadGroup(RealtimeThreadGroup parent, java.lang.String name) Creates a new realtime thread group with its scheduler type inherited from parent.
RealtimeThreadGroup(RealtimeThreadGroup parent, java.lang.String name, java.lang.Class<? extends Scheduler> scheduler) Creates a new realtime thread group with its scheduler type inherited from parent.
RealtimeThreadGroup(java.lang.String name) Creates a new group with the current ThreadGroup instance as its parent and that parent's scheduler type for its scheduler type.

Method Summary

Modifier and Type	Method and Description
SchedulingParameters	getMaxEligibility() Finds the upper bound on scheduling eligibility that tasks in this group may have.
java.lang.Class<? extends Scheduler>	getScheduler() Finds the type of scheduler tasks in this group may use.
RealtimeThreadGroup	setMaxEligibility(SchedulingParameters parameters) Sets the upper bound on scheduling eligibility that tasks in this group may have.
void	visitThreadGroups(java.util.function.Consumer<java.lang.ThreadGroup> visitor) Performs some operation on all the groups in the current group.
void	visitThreadGroups(java.util.function.Consumer<java.lang.ThreadGroup> visitor, boolean recursive) Performs some operation on all th groups in the current group.
void	visitThreads(java.util.function.Consumer<java.lang.Thread> visitor) Visit all java.lang.Thread instances contained by this group.
void	visitThreads(java.util.function.Consumer<java.lang.Thread> visitor, boolean recurse) Visit all java.lang.Thread instances contained by this group and optionally all ThreadGroup instances contained within recursively.

Methods inherited from class java.lang.ThreadGroup

activeCount, activeGroupCount, allowThreadSuspension, checkAccess, destroy, enumerate, enumerate, enumerate, enumerate, getMaxPriority, getName, getParent, interrupt, isDaemon, isDestroyed, list, parentOf, resume, setDaemon, setMaxPriority, stop, suspend, toString, uncaughtException

Methods inherited from class java.lang.Object

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

Constructor Detail

RealtimeThreadGroup

public RealtimeThreadGroup(RealtimeThreadGroup parent,
                           java.lang.String name,
                           java.lang.Class<? extends Scheduler> scheduler)

Creates a new realtime thread group with its scheduler type inherited from parent.

Parameters:

parent - The parent group of the new group

name - The name of the new group

scheduler - a scheduler class limiting the schedulers allowed for scheduling group members. When null inherits from parent. Instances of java.lang.ThreadGroup do not have a scheduler and may not contain instances of RealtimeSchedulerGroup.

Throws:

StaticIllegalStateException - when the parent ThreadGroup instance is not an instance of RealtimeThreadGroup.

IllegalAssignmentError - when the parent ThreadGroup instance is not assignable to this.

RealtimeThreadGroup

public RealtimeThreadGroup(RealtimeThreadGroup parent,
                           java.lang.String name)

Creates a new realtime thread group with its scheduler type inherited from parent.

Parameters:

parent - The parent group of the new group

name - The name of the new group

Throws:

StaticIllegalStateException - when the parent ThreadGroup instance is not an instance of RealtimeThreadGroup.

IllegalAssignmentError - when the parent ThreadGroup instance is not assignable to this.

RealtimeThreadGroup

public RealtimeThreadGroup(java.lang.String name)
                    throws StaticIllegalStateException,
                           IllegalAssignmentError

Creates a new group with the current ThreadGroup instance as its parent and that parent's scheduler type for its scheduler type. That parent must be an instance of RealtimeThreadGroup. The primordial realtime thread group has Scheduler.class as its scheduler type.

Parameters:

name - The name of the new group

Throws:

StaticIllegalStateException - when the parent ThreadGroup instance is not an instance of RealtimeThreadGroup.

IllegalAssignmentError - when the parent ThreadGroup instance is not assignable to this.

Method Detail

getScheduler

public java.lang.Class<? extends Scheduler> getScheduler()

Finds the type of scheduler tasks in this group may use. The scheduler of each thread must be an instance of the type returned. The default is class<Scheduler>, but it may be set to any subtype.

Returns:

the scheduler type

getMaxEligibility

public SchedulingParameters getMaxEligibility()

Finds the upper bound on scheduling eligibility that tasks in this group may have. For example, when it is an instance of PriorityParameters, it gives the maximum base priority any task in this group.

Returns:

the scheduling parameter instance denoting the upper bound on the scheduling eligibility of threads in this group, The maximal possible eligibility is represented by an instance of SchedulingParamters, not one of its subclasses, with an affinity that contains all processors available to the process. This may not be null.

setMaxEligibility

public RealtimeThreadGroup setMaxEligibility(SchedulingParameters parameters)
                                      throws StaticIllegalStateException

Sets the upper bound on scheduling eligibility that tasks in this group may have. For example, when it is an instance of PriorityParameters, it sets the maximum base priority any task in this group may have. When a task in the group has a higher eligibility than specified in parameters, the task's eligibility is silently set to the max specified in parameters.

When the new eligibility is higher than that of any parent's eligibility, then eligibility is set to the minimum of those priorities. When a child of this RealtimeThreadGroup has a higher max eligibility than specified in parameters, its max eligibility is silently set to the max specified in parameters as if setMaxEligibility were invoked on it recursively.

When a task in this RealtimeThreadGroup or a child of this RealtimeThreadGroup has previously had its maximum eligibility reduced by a call to this method, setting a higher maximum eligibility via this method will not automatically reraise its eligibility. Please note that this method is not thread safe, as it uses methods from ThreadGroup that are not thread safe.

Parameters:

parameters - The SchedulingParameter instance denoting the new upper bound on the scheduling eligibility of threads in this group.

Returns:

this

Throws:

StaticIllegalArgumentException - when parameters are not consistent with the scheduler type. The scheduler specified must be specific enough that only mutually compatible SchedulingParameters could be set. For example, Scheduler is not sufficient to restrict the scheduling parameters to compatible types, but PriorityScheduler does since all PriorityScheduler instances require PriorityParameters.

StaticIllegalStateException - when parameters is a higher eligibility than the max eligibility enforced by a SchedulingParameters above this in the hierarchy.

visitThreads

public void visitThreads(java.util.function.Consumer<java.lang.Thread> visitor,
                         boolean recurse)
                  throws ForEachTerminationException

Visit all java.lang.Thread instances contained by this group and optionally all ThreadGroup instances contained within recursively.

Parameters:

visitor - A consumer of each schedulable instance.

recurse - A boolean to indicated that the visit should be recursive.

Throws:

ForEachTerminationException

visitThreads

public void visitThreads(java.util.function.Consumer<java.lang.Thread> visitor)
                  throws ForEachTerminationException

Visit all java.lang.Thread instances contained by this group. It is equivalent to calling visitThreads(Consumer, boolean) with recurse set to false.

Parameters:

visitor - A consumer of each thread instance

Throws:

ForEachTerminationException - when the visitor is prematurely ended.

visitThreadGroups

public void visitThreadGroups(java.util.function.Consumer<java.lang.ThreadGroup> visitor)
                       throws ForEachTerminationException

Performs some operation on all the groups in the current group. The traversal of these children continues as long as visitor does not throw a ForEachTerminationException. Thus the traversal can be prematurely ended by visitor throwing this exception, e.g., when a particular element is found. It is equivalent to a call to visitThreadGroups(Consumer, boolean) with recurse set to false.

Parameters:

visitor - The function to be called on each child thread group.

Throws:

ForEachTerminationException - when the traversal ends prematurely.

visitThreadGroups

public void visitThreadGroups(java.util.function.Consumer<java.lang.ThreadGroup> visitor,
                              boolean recursive)

Performs some operation on all th groups in the current group. The traversal of these children continues as long as visitor does not throw a ForEachTerminationException. Thus the traversal can be prematurely ended by visitor throwing this exception, e.g., when a particular element is found.

Parameters:

visitor - The function to be called on each child thread group.

recursive - A boolean to determine whether or not all subgroups are included, where true means yes and false means no.

Throws:

ForEachTerminationException - when the traversal ends prematurely.