javax.realtime.DSS
Class Resource

java.lang.Object
  javax.realtime.DSS.Resource

Direct Known Subclasses:

FIFOResource, PreemptableResource, PriorityCeilingResource, PriorityInheritanceResource, PriorityResource

public abstract class Resource

extends java.lang.Object

Super class for all unit resources, i.e., object contended for by

Field Summary

protected RelativeTime	busyTimeThusFar
protected int	count The re-entrancy count of this Resource; zero when not held by any RealtimeThread;
protected AbsoluteTime	creationTime
RealtimeThread	holderThread The current holder of this Resource; if null, the resource is not currently held.
protected AbsoluteTime	lastGrant
protected AbsoluteTime	lastRelease
java.lang.String	name The name of this Resource.
protected boolean	signalPriorityInversion
protected WaiterSet	waiters The waiter set of this resource, used to implement the scheduling policy of this resource.

Constructor Summary

Resource(java.lang.String name, boolean signalPriorityInversion)
Constructor

Method Summary

abstract void	adjustPriority(RealtimeThread thread) Adjust the priority of this RealtimeThread, according to resources currently held.
double	dutyCycle()
void	finalize()
static java.util.Set	getExtent() To support backtracking
protected void	giveResourceTo(RealtimeThread thread) Give this Resource to the given thread.
int	maxWaiterPriority() Test whether this resource is currently experiencing priority inversion, i.e., is held by a RealtimeThread with a priority later than that of a waiting thread.
static void	printAllStatistics()
void	printStatistics()
abstract void	release() Release this resource.
void	releaseIfHeld() Release this Resource if held.
abstract void	seize() Seize this resource, waiting if necessary.
void	seize(Resource second) Conjunctive seize, i.e., seize both this and the given resource.
void	seizeIfNotHeld() Seize this Resource if not already held.
static void	setExtent(java.util.Set newExtent)
java.lang.String	toString() Construct a printable representation of this Resource
java.util.Iterator	waiterIterator()

Methods inherited from class java.lang.Object

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

Field Detail

name

public java.lang.String name

The name of this Resource.

creationTime

protected AbsoluteTime creationTime

lastGrant

protected AbsoluteTime lastGrant

lastRelease

protected AbsoluteTime lastRelease

busyTimeThusFar

protected RelativeTime busyTimeThusFar

holderThread

public RealtimeThread holderThread

The current holder of this Resource; if null, the resource is not currently held.

count

protected int count

The re-entrancy count of this Resource; zero when not held by any RealtimeThread;

signalPriorityInversion

protected boolean signalPriorityInversion

waiters

protected WaiterSet waiters

The waiter set of this resource, used to implement the scheduling policy of this resource.

Constructor Detail

Resource

public Resource(java.lang.String name,
                boolean signalPriorityInversion)

Constructor

Parameters:

name - the name of this resource

Method Detail

finalize

public void finalize()

seize

public abstract void seize()
                    throws java.lang.InterruptedException,
                           ThreadTerminatedException

Seize this resource, waiting if necessary.

Throws:

java.lang.InterruptedException

ThreadTerminatedException

seize

public void seize(Resource second)
           throws java.lang.InterruptedException,
                  ThreadTerminatedException

Conjunctive seize, i.e., seize both this and the given resource. If one (or more is not free, wait until they are both free)

Parameters:

second - The second Resource to seize, in addition to this Resource

Throws:

java.lang.InterruptedException - Thrown if the seizing RealtimeThread is shut down while waiting for a Resource

ThreadTerminatedException

seizeIfNotHeld

public void seizeIfNotHeld()
                    throws java.lang.InterruptedException,
                           ThreadTerminatedException

Seize this Resource if not already held. This method can be useful after hold method calls where it is unknown upon return whether the resource is still held or was stolen away, e.g., by a higher priority thread.

Throws:

java.lang.InterruptedException

ThreadTerminatedException

release

public abstract void release()
                      throws ThreadTerminatedException

Release this resource.

Throws:

ThreadTerminatedException

releaseIfHeld

public void releaseIfHeld()
                   throws ThreadTerminatedException

Release this Resource if held. This method can be useful after hold method calls where it is unknown upon return whether the resource is still held or was stolen away, e.g., by a higher priority thread.

Throws:

ThreadTerminatedException

giveResourceTo

protected void giveResourceTo(RealtimeThread thread)
                       throws ThreadTerminatedException

Give this Resource to the given thread. This maintains all the resource possession invariants on the new thread and the holder thread, each of which may be null, indicating that the resource is not held by any thread. Implementation note: this method must be called by seize and release methods in subclasses, in order for resource utilization statistics to be properly logged.

Parameters:

thread - the thread to be given the Resource; may be null

Throws:

ThreadTerminatedException

waiterIterator

public java.util.Iterator waiterIterator()

dutyCycle

public double dutyCycle()

adjustPriority

public abstract void adjustPriority(RealtimeThread thread)

Adjust the priority of this RealtimeThread, according to resources currently held.

toString

public java.lang.String toString()

Construct a printable representation of this Resource

Returns:

the printable representation

maxWaiterPriority

public int maxWaiterPriority()

Test whether this resource is currently experiencing priority inversion, i.e., is held by a RealtimeThread with a priority later than that of a waiting thread.

Returns:

true iff this resource is experiencing priority inversion

printAllStatistics

public static void printAllStatistics()

printStatistics

public void printStatistics()

getExtent

public static java.util.Set getExtent()

To support backtracking

Returns:

the extent set for

setExtent

public static void setExtent(java.util.Set newExtent)