ptolemy.actor.process
Class Branch

java.lang.Object
  ptolemy.actor.process.Branch

All Implemented Interfaces:

java.lang.Runnable

public class Branch
extends java.lang.Object
implements java.lang.Runnable

A Branch transfers tokens through a channel that crosses a composite actor boundary. Branch implements the Runnable class and the execution of a branch object is controlled by an instantiation of the BranchController class. Each branch object is assigned two receiver objects and each of these receiver objects must implement the ProcessReceiver class. One of the assigned receivers is referred to as the producer receiver (the channel source) and the other is referred to as the consumer receiver (the channel destination).

During its execution a branch attempts to get data from the producer receiver and put data in the consumer receiver. The communication semantics of the producer receiver get() method are dependent upon the model of computation associated with the producer receiver. In cases where a blocking read occurs, the producer receiver registers the block with the calling branch leading to a blocked branch. So that the producer receiver knows which branch to register the block with, a branch always invokes the receiver's get() method by passing itself as an argument. A blocked branch registers the block with the branch controller that it is assigned to.

Putting data in a consumer receiver is symmetrically analogous to getting data from a producer receiver. In cases where a blocking write occurs, the consumer receiver registers the block with the calling branch leading to a blocked branch. So that the consumer receiver knows which branch to register the block with, a branch always invokes the receiver's put() method by passing itself as an argument.

Since:

Ptolemy II 1.0

Version:

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

Author:

John S. Davis II

Accepted Rating:

Red (davisj)

Proposed Rating:

Red (davisj)

Field Summary

private boolean	_active
private ProcessReceiver	_consumerReceiver
private BranchController	_controller
private ProcessReceiver	_producerReceiver

Constructor Summary

Branch(BranchController controller)
Deprecated. Use this constructor for testing purposes only.

Branch(ProcessReceiver producerReceiver, ProcessReceiver consumerReceiver, BranchController controller)
Construct a branch object with a producer receiver, a consumer receiver and a branch controller.

Method Summary

ProcessReceiver	getConsumerReceiver() Return the consumer receiver that this branch puts data into.
ProcessReceiver	getProducerReceiver() Return the producer receiver that this branch gets data from.
boolean	isActive() Return true if this branch is active.
void	run() Repeatedly transfer a single token between the producer receiver and the consumer receiver as long as the branch is active or until a TerminateProcessException is thrown.
void	setActive(boolean value) Set a flag indicating this branch is no longer active.
void	transferToken() Transfer a single token from the producer receiver to the consumer receiver.

Methods inherited from class java.lang.Object

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

Field Detail

_active

private boolean _active

_controller

private BranchController _controller

_producerReceiver

private ProcessReceiver _producerReceiver

_consumerReceiver

private ProcessReceiver _consumerReceiver

Constructor Detail

Branch

public Branch(BranchController controller)
       throws IllegalActionException

Deprecated. Use this constructor for testing purposes only.

Construct a branch object with a branch controller.

Parameters:

controller - The branch controller assigned to this branch.

Throws:

IllegalActionException - Not thrown in this base class.

Branch

public Branch(ProcessReceiver producerReceiver,
              ProcessReceiver consumerReceiver,
              BranchController controller)
       throws IllegalActionException

Construct a branch object with a producer receiver, a consumer receiver and a branch controller.

Parameters:

producerReceiver - The producer receiver assigned to this branch.

consumerReceiver - The consumer receiver assigned to this branch.

controller - The branch controller assigned to this branch.

Throws:

IllegalActionException - If the receivers assigned to this branch are null or improperly configured.

Method Detail

getConsumerReceiver

public ProcessReceiver getConsumerReceiver()

Return the consumer receiver that this branch puts data into.

Returns:

The consumer receiver that this branch puts data into.

See Also:

BoundaryDetector

getProducerReceiver

public ProcessReceiver getProducerReceiver()

Return the producer receiver that this branch gets data from.

Returns:

The producer receiver that this branch gets data from.

See Also:

BoundaryDetector

isActive

public boolean isActive()

Return true if this branch is active.

Returns:

True if this branch is still alive.

run

public void run()

Repeatedly transfer a single token between the producer receiver and the consumer receiver as long as the branch is active or until a TerminateProcessException is thrown.

Specified by:

run in interface java.lang.Runnable

setActive

public void setActive(boolean value)

Set a flag indicating this branch is no longer active.

Parameters:

value - A boolean indicating whether this branch is still active.

transferToken

public void transferToken()
                   throws IllegalActionException

Transfer a single token from the producer receiver to the consumer receiver. If either the producer receiver or consumer receiver is null then return without attempting token transfer.

Throws:

IllegalActionException - If the token is not acceptable to one of the ports (e.g., wrong type).