ptolemy.domains.de.lib
Class Queue

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.Transformer
                              ptolemy.domains.de.lib.Queue

All Implemented Interfaces:

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

Direct Known Subclasses:

SharedQueue

public class Queue
extends Transformer

This actor implements a queue. When a token is received on the input port, it is stored in the queue. When the trigger port receives a token, the oldest element in the queue is produced on the output. If there is no element in the queue when a token is received on the trigger port, then no output is produced. In this circumstance, if persistentTrigger is true then the next time an input is received, it is sent immediately to the output.

The inputs can be of any token type, and the output is constrained to be of a type at least that of the input. If the capacity parameter is negative or zero (the default), then the capacity is infinite. Otherwise, the capacity is given by that parameter, and inputs received when the queue is full are discarded. Whenever the size of the queue changes, the new size is produced on the size output port. If an input arrives at the same time that an output is produced, then the size port gets two events at the same time.

Since:

Ptolemy II 2.0

Version:

$Id: Queue.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Steve Neuendorffer and Edward A. Lee

See Also:

Serialized Form

Accepted Rating:

Yellow (eal)

Proposed Rating:

Yellow (eal)

Nested Class Summary

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

Entity.ContainedObjectsIterator

Field Summary

private boolean	_persistentTrigger An indicator of whether a trigger token was received in the last fire() method invocation.
protected FIFOQueue	_queue The FIFOQueue.
protected int	_removeTokens The number of tokens that should be removed from the queue in postfire().
protected Token	_token Token received in the fire() method for inclusion in the queue in the postfire() method.
Parameter	capacity The capacity of the queue.
Parameter	persistentTrigger If set to true, then if a trigger arrives when the queue is empty, it is remembered, and the next time an input arrives, it is sent immediately to the output.
TypedIOPort	size The current size of the queue.
TypedIOPort	trigger The trigger port, which has undeclared type.

Fields inherited from class ptolemy.actor.lib.Transformer

input, output

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

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

Method Summary

void	attributeChanged(Attribute attribute) React to a change in an attribute.
java.lang.Object	clone(Workspace workspace) Clone the actor into the specified workspace.
void	fire() Put a new input token on the queue and/or produce output data from the queue.
void	initialize() Clear the cached input tokens.
boolean	postfire() Commit additions or removals from the queue.
boolean	prefire() If there is no input on the trigger port, return false, indicating that this actor does not want to fire.
void	preinitialize() Override the base class to declare that the output does not depend on the input in a firing.
void	wrapup() Clear the queue tokens.

Methods inherited from class ptolemy.actor.TypedAtomicActor

_addPort, _fireAt, _fireAt, attributeTypeChanged, clone, newPort, typeConstraintList, typeConstraints

Methods inherited from class ptolemy.actor.AtomicActor

_actorFiring, _actorFiring, addActorFiringListener, addInitializable, connectionsChanged, createReceivers, declareDelayDependency, getCausalityInterface, getDirector, getExecutiveDirector, getManager, inputPortList, isFireFunctional, isStrict, iterate, newReceiver, outputPortList, 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, _recordDecoratedAttributes, _removeAttribute, _splitName, _stripNumericSuffix, addChangeListener, addDebugListener, attributeList, attributeList, deepContains, depthInHierarchy, description, description, event, executeChangeRequests, exportMoML, exportMoML, exportMoML, exportMoML, exportMoMLPlain, getAttribute, getAttributes, getChangeListeners, getClassName, getDecoratorAttribute, getDecoratorAttributes, getDerivedLevel, getDerivedList, getDisplayName, getFullName, getModelErrorHandler, getName, getName, getSource, handleModelError, isDeferringChangeRequests, isOverridden, isPersistent, lazyContainedObjectsIterator, 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

createReceivers, getCausalityInterface, getDirector, getExecutiveDirector, 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, 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

capacity

public Parameter capacity

The capacity of the queue. If the value is positive, then it specifies the capacity of the queue. If it is negative or 0, then it specifies that the capacity is infinite. This is an integer with default 0.

persistentTrigger

public Parameter persistentTrigger

If set to true, then if a trigger arrives when the queue is empty, it is remembered, and the next time an input arrives, it is sent immediately to the output. This is a boolean with default false.

size

public TypedIOPort size

The current size of the queue. This port produces an output whenever the size changes. It has type int.

trigger

public TypedIOPort trigger

The trigger port, which has undeclared type. If this port receives a token, then the oldest token in the queue will be emitted on the output port.

_queue

protected FIFOQueue _queue

The FIFOQueue.

_removeTokens

protected int _removeTokens

The number of tokens that should be removed from the queue in postfire().

_token

protected Token _token

Token received in the fire() method for inclusion in the queue in the postfire() method.

_persistentTrigger

private boolean _persistentTrigger

An indicator of whether a trigger token was received in the last fire() method invocation.

Constructor Detail

Queue

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

Construct an actor with the given container and name.

Parameters:

container - The container.

name - The name of this actor.

Throws:

IllegalActionException - If the actor 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

React to a change in an attribute. If the attribute is capacity, then change the capacity of the queue. If the size of the queue currently exceeds the specified capacity, then throw an exception.

Overrides:

attributeChanged in class NamedObj

Parameters:

attribute - The attribute that changed.

Throws:

IllegalActionException - If the current size of the queue exceeds the specified capacity.

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 ports.

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 has has an attribute that cannot be cloned.

See Also:

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

fire

public void fire()
          throws IllegalActionException

Put a new input token on the queue and/or produce output data from the queue. Specifically, if there is a new token on the input port, then put it on the input queue. Then, if there is a token in the trigger port and the queue is not empty, then send the oldest token on the queue to the output port. Send the resulting queue size to the output size output port.

Specified by:

fire in interface Executable

Overrides:

fire in class AtomicActor

Throws:

IllegalActionException - If getting tokens from input and trigger ports or sending token to output throws it.

initialize

public void initialize()
                throws IllegalActionException

Clear the cached input tokens.

Specified by:

initialize in interface Initializable

Overrides:

initialize in class AtomicActor

Throws:

IllegalActionException - If there is no director.

postfire

public boolean postfire()
                 throws IllegalActionException

Commit additions or removals from the queue.

Specified by:

postfire in interface Executable

Overrides:

postfire in class AtomicActor

Returns:

True.

Throws:

IllegalActionException - If the superclass throws it.

prefire

public boolean prefire()
                throws IllegalActionException

If there is no input on the trigger port, return false, indicating that this actor does not want to fire. This has the effect of leaving input values in the input ports, if there are any.

Specified by:

prefire in interface Executable

Overrides:

prefire in class AtomicActor

Returns:

True if this actor is ready for firing, false otherwise.

Throws:

IllegalActionException - If there is no director.

preinitialize

public void preinitialize()
                   throws IllegalActionException

Override the base class to declare that the output does not depend on the input in a firing.

Specified by:

preinitialize in interface Initializable

Overrides:

preinitialize in class AtomicActor

Throws:

IllegalActionException - If the superclass throws it.

wrapup

public void wrapup()
            throws IllegalActionException

Clear the queue tokens.

Specified by:

wrapup in interface Initializable

Overrides:

wrapup in class AtomicActor

Throws:

IllegalActionException - If the superclass throws it.