ptolemy.backtrack.automatic.ptolemy.actor.lib
Class PoissonClock

java.lang.Object
  ptolemy.kernel.util.NamedObj
      ptolemy.kernel.InstantiableNamedObj
          ptolemy.kernel.Entity
              ptolemy.kernel.ComponentEntity
                  ptolemy.actor.AtomicActor
                      ptolemy.actor.TypedAtomicActor
                          ptolemy.actor.lib.Source
                              ptolemy.actor.lib.TimedSource
                                  ptolemy.backtrack.automatic.ptolemy.actor.lib.PoissonClock

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, TimedActor, TypedActor, Rollbackable, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable

public class PoissonClock
extends TimedSource
implements Rollbackable

This actor produces a signal that is piecewise constant, with transitions between levels taken at times given by a Poisson process. It has various uses. Its simplest use in the DE domain is to generate a sequence of events at intervals that are spaced randomly, according to an exponential distribution. In CT, it can be used to generate a piecewise constant waveform with randomly spaced transition times. In both domains, the output value can cycle through a set of values.

The mean time between events is given by the meanTime parameter. An event is defined to be the transition to a new output value. The default mean time is 1.0.

The values parameter must contain an ArrayToken, or an exception will be thrown when it is set. By default the elements of the array are IntTokens with values 1 and 0, Thus, the default output value is always 1 or 0.

In the initialize() method and in each invocation of the fire() method, the actor uses the fireAt() method of the director to request the next firing. The first firing is always at the start time, unless the parameter fireAtStart is changed to false. It may in addition fire at any time in response to a trigger input. On such firings, it simply repeats the most recent output (or generates a new output if the time is suitable.) Thus, the trigger, in effect, asks the actor what its current output value is. Some directors, such as those in CT, may also fire the actor at other times, without requiring a trigger input. Again, the actor simply repeats the previous output. Thus, the output can be viewed as samples of the piecewise constant waveform, where the time of each sample is the time of the firing that produced it.

The type of the output can be any token type. This type is inferred from the element type of the values parameter.

Since:

Ptolemy II 1.0

Version:

$Id: PoissonClock.java,v 1.34 2007/12/07 06:25:58 cxh Exp $

Author:

Edward A. Lee

See Also:

Serialized Form

Accepted Rating:

Yellow (yuhong)

Proposed Rating:

Yellow (eal)

Nested Class Summary

Nested classes/interfaces inherited from class ptolemy.kernel.Entity

Entity.ContainedObjectsIterator

Field Summary

protected Checkpoint	$CHECKPOINT
protected CheckpointRecord	$RECORD$$CHECKPOINT
Parameter	fireAtStart If true, then this actor will request a firing at the start time.
Parameter	meanTime The mean time between events, where the output value transitions.
Parameter	values The values that will be produced at the output.

Fields inherited from class ptolemy.actor.lib.TimedSource

stopTime

Fields inherited from class ptolemy.actor.lib.Source

output, trigger

Fields inherited from class ptolemy.actor.AtomicActor

_actorFiringListeners, _initializables, _notifyingActorFiring, _stopRequested

Fields inherited from class ptolemy.kernel.util.NamedObj

_changeListeners, _changeLock, _changeRequests, _debugging, _debugListeners, _elementName, _isPersistent, _verbose, _workspace, ATTRIBUTES, CLASSNAME, COMPLETE, CONTENTS, DEEP, FULLNAME, LINKS

Fields inherited from interface ptolemy.actor.Executable

COMPLETED, NOT_READY, STOP_ITERATING

Constructor Summary

PoissonClock(CompositeEntity container, java.lang.String name)
Construct an actor with the specified container and name.

Method Summary

void	$COMMIT(long timestamp) Commit changes up to the given timestamp, but not including changes made at timestamp and afterward.
Checkpoint	$GET$CHECKPOINT() Get the checkpoint object that monitors this rollbackable object.
void	$RESTORE(long timestamp, boolean trim) Restore a previous state to all the private fields of this rollbackable object.
java.lang.Object	$SET$CHECKPOINT(Checkpoint checkpoint) Set the checkpoint object of this rollbackable object.
void	attributeChanged(Attribute attribute) If the argument is the meanTime parameter, check that it is positive.
java.lang.Object	clone(Workspace workspace) Clone the actor into the specified workspace.
void	fire() Output the current value.
void	initialize() Schedule the first firing at time zero and initialize local variables.
boolean	postfire() Update the state of the actor and schedule the next firing, if appropriate.

Methods inherited from class ptolemy.actor.lib.TimedSource

getModelStopTime, getStopTime, wrapup

Methods inherited from class ptolemy.actor.lib.Source

prefire

Methods inherited from class ptolemy.actor.TypedAtomicActor

_addPort, attributeTypeChanged, clone, newPort, typeConstraintList

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, _createReceivers, addActorFiringListener, addInitializable, connectionsChanged, getDirector, getExecutiveDirector, getFunctionDependency, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, preinitialize, pruneDependencies, recordFiring, removeActorFiringListener, removeDependency, removeInitializable, setContainer, stop, stopFire, terminate

Methods inherited from class ptolemy.kernel.ComponentEntity

_adjustDeferrals, _checkContainer, _getContainedObject, _propagateExistence, getContainer, instantiate, isAtomic, isOpaque, moveDown, moveToFirst, moveToIndex, moveToLast, moveUp, propagateExistence, setName

Methods inherited from class ptolemy.kernel.Entity

_description, _exportMoMLContents, _removePort, _validateSettables, connectedPortList, connectedPorts, containedObjectsIterator, getAttribute, getPort, getPorts, linkedRelationList, linkedRelations, portList, removeAllPorts, setClassDefinition, uniqueName

Methods inherited from class ptolemy.kernel.InstantiableNamedObj

_setParent, exportMoML, getChildren, getElementName, getParent, getPrototypeList, isClassDefinition, isWithinClassDefinition

Methods inherited from class ptolemy.kernel.util.NamedObj

_addAttribute, _adjustOverride, _attachText, _cloneFixAttributeFields, _debug, _debug, _debug, _debug, _debug, _getIndentPrefix, _isMoMLSuppressed, _markContentsDerived, _propagateValue, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeList, attributeList, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, message, propagateValue, propagateValues, removeChangeListener, removeDebugListener, requestChange, setClassName, setDeferringChangeRequests, setDerivedLevel, setDisplayName, setModelErrorHandler, setPersistent, setSource, sortContainedObjects, toplevel, toString, validateSettables, workspace

Methods inherited from class java.lang.Object

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

Methods inherited from interface ptolemy.actor.Actor

getDirector, getExecutiveDirector, getFunctionDependency, getManager, inputPortList, newReceiver, outputPortList

Methods inherited from interface ptolemy.actor.Executable

isFireFunctional, isStrict, iterate, stop, stopFire, terminate

Methods inherited from interface ptolemy.actor.Initializable

addInitializable, preinitialize, removeInitializable

Methods inherited from interface ptolemy.kernel.util.Nameable

description, getContainer, getDisplayName, getFullName, getName, getName, setName

Methods inherited from interface ptolemy.kernel.util.Derivable

getDerivedLevel, getDerivedList, propagateValue

Field Detail

$CHECKPOINT

protected transient Checkpoint $CHECKPOINT

fireAtStart

public Parameter fireAtStart

If true, then this actor will request a firing at the start time. Otherwise, the first firing will be requested at the first random time. This is a boolean-valued parameter that defaults to true.

meanTime

public Parameter meanTime

The mean time between events, where the output value transitions. This parameter must contain a DoubleToken.

values

public Parameter values

The values that will be produced at the output. This parameter can contain any ArrayToken, and it defaults to {1, 0}.

$RECORD$$CHECKPOINT

protected transient CheckpointRecord $RECORD$$CHECKPOINT

Constructor Detail

PoissonClock

public PoissonClock(CompositeEntity container,
                    java.lang.String name)
             throws NameDuplicationException,
                    IllegalActionException

Construct an actor with the specified container and name.

Parameters:

container - The container.

name - The name of this actor.

Throws:

IllegalActionException - If the entity cannot be contained by the proposed container.

NameDuplicationException - If the container already has an actor with this name.

Method Detail

attributeChanged

public void attributeChanged(Attribute attribute)
                      throws IllegalActionException

If the argument is the meanTime parameter, check that it is positive.

Overrides:

attributeChanged in class TimedSource

Parameters:

attribute - The attribute that changed.

Throws:

IllegalActionException - If the meanTime value is not positive.

clone

public java.lang.Object clone(Workspace workspace)
                       throws java.lang.CloneNotSupportedException

Clone the actor into the specified workspace. This calls the base class and then sets the parameter public members to refer to the parameters of the new actor.

Overrides:

clone in class AtomicActor

Parameters:

workspace - The workspace for the new object.

Returns:

A new actor.

Throws:

java.lang.CloneNotSupportedException - If a derived class contains an attribute that cannot be cloned.

See Also:

NamedObj.exportMoML(Writer, int, String), NamedObj.setDeferringChangeRequests(boolean)

fire

public void fire()
          throws IllegalActionException

Output the current value.

Specified by:

fire in interface Executable

Overrides:

fire in class Source

Throws:

IllegalActionException - If there is no director.

initialize

public void initialize()
                throws IllegalActionException

Schedule the first firing at time zero and initialize local variables.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class TimedSource

Throws:

IllegalActionException - If the fireAt() method of the director throws it.

postfire

public boolean postfire()
                 throws IllegalActionException

Update the state of the actor and schedule the next firing, if appropriate.

Specified by:

postfire in interface Executable

Overrides:

postfire in class TimedSource

Returns:

True if execution can continue into the next iteration.

Throws:

IllegalActionException - If the director throws it when scheduling the next firing.

$COMMIT

public void $COMMIT(long timestamp)

Description copied from interface: Rollbackable

Commit changes up to the given timestamp, but not including changes made at timestamp and afterward.

Specified by:

$COMMIT in interface Rollbackable

Parameters:

timestamp - The timestamp.

$RESTORE

public void $RESTORE(long timestamp,
                     boolean trim)

Description copied from interface: Rollbackable

Restore a previous state to all the private fields of this rollbackable object.

Specified by:

$RESTORE in interface Rollbackable

Parameters:

timestamp - The timestamp taken at the time when the previous state was recorded.

trim - Whether to delete the records used for the rollback.

See Also:

Checkpoint.rollback(long, boolean)

$GET$CHECKPOINT

public final Checkpoint $GET$CHECKPOINT()

Description copied from interface: Rollbackable

Get the checkpoint object that monitors this rollbackable object.

Specified by:

$GET$CHECKPOINT in interface Rollbackable

Returns:

The checkpoint object.

$SET$CHECKPOINT

public final java.lang.Object $SET$CHECKPOINT(Checkpoint checkpoint)

Description copied from interface: Rollbackable

Set the checkpoint object of this rollbackable object. A merge operation is performed on the current checkpoint object and the new checkpoint object, so that the two checkpoint objects monitor the same set of objects when this function returns.

Specified by:

$SET$CHECKPOINT in interface Rollbackable

Parameters:

checkpoint - The new checkpoint object.

Returns:

This rollbackable object itself.

See Also:

Checkpoint.setCheckpoint(Checkpoint)