Package ptolemy.actor.lib

Class Stop

  • All Implemented Interfaces:
    java.lang.Cloneable, Actor, Executable, FiringsRecordable, Initializable, TypedActor, Changeable, Debuggable, DebugListener, Derivable, Instantiable, ModelErrorHandler, MoMLExportable, Moveable, Nameable
    public class Stop
extends Sink

    An actor that stops execution of a model when it receives a true token on any input channel. This is accomplished by calling finish() on the director, which requests that the current iteration be completed and then the execution be halted. This actor will also call stopFire() which requests that any actors that are firing concurrently in separate threads conclude their firings. This is necessary to support threaded domains like PN. If the input is not connected to anything, then this actor requests a stop whenever it fires.

    When exactly this stops the execution depends on the domain. For example, in DE, if an event with time stamp T and value true arrives at this actor, then the current iteration will be concluded, and then the model will halt. Concluding the current iteration means processing all events in the event queue with time stamp T. Thus, it is possible for actors to be invoked after this one is invoked with a true input.

    In SDF, if this actor receives true, then the current iteration is concluded and then execution is stopped. Similarly in SR.

    In PN, where each actor has its own thread, there is no well-defined notion of an iteration. The finish() method of the manager calls stopFire() on all actors, which for threaded actors results in halting them upon their next attempt to read an input or write an output. When all actor threads have stopped, the iteration concludes and the model halts. NOTE: This is not the best way to stop a PN model! This mechanism is nondeterministic in the sense that there is no way to control exactly what data is produced or consumed on the connections before the model stops. To stop a PN model, it is better to design the model so that all actors are starved of data when the model is to stop. The director will detect this starvation, and halt the model. Nonetheless, if the nondeterminism is acceptable, this actor can be used.

    Since:
    Ptolemy II 2.1
    Version:
    $Id$
    Author:
    Edward A. Lee
    Pt.AcceptedRating:
    Green (neuendor)
    Pt.ProposedRating:
    Green (eal)

    • Field Detail

      • _hideName

        public SingletonParameter _hideName
        The parameter that hides the name of the actor. The default value is true.

    • Method Detail

      • postfire

        public boolean postfire()
                 throws IllegalActionException
        Read one token from each input channel that has a token, and if any token is true, call finish() on the manager. If nothing at all is connected to the input port, then call finish() unconditionally.
        Specified by:
        postfire in interface Executable
        Overrides:
        postfire in class AtomicActor<TypedIOPort>
        Returns:
        False if this actor is trying to stop execution if any token is true or if the input is not connected. If this actor is not trying to stop execution, then return the value returned by super.postfire().
        Throws:
        IllegalActionException - If there is no director or if there is no manager, or if the container is not a CompositeActor.