Signal.m

classdef Signal < OpenClass
    % Signal Job class representing a signal (e.g., negative customer in G-networks)
    %
    % Signal is a specialized OpenClass for modeling signals in queueing networks.
    % Unlike regular customers, signals can have special effects on queues they
    % visit, such as removing jobs (negative signals).
    %
    % @brief Job class for modeling signals in G-networks and related models
    %
    % Key characteristics:
    % - Extends OpenClass with signal-specific behavior
    % - Supports different signal types (NEGATIVE, REPLY)
    % - NEGATIVE signals remove jobs from destination queues
    % - Used in G-networks (Gelenbe networks)
    %
    % Signal types:
    % - SignalType.NEGATIVE: Removes a job from the destination queue
    % - SignalType.REPLY: Triggers a reply action
    %
    % Example:
    % @code
    % model = Network('GNetwork');
    % source = Source(model, 'Source');
    % sink = Sink(model, 'Sink');
    % queue = Queue(model, 'Queue', SchedStrategy.FCFS);
    % posClass = OpenClass(model, 'Positive');       % Normal customers
    % negClass = Signal(model, 'Negative', SignalType.NEGATIVE);  % Negative signals
    % source.setArrival(posClass, Exp(1.0));
    % source.setArrival(negClass, Exp(0.3));
    % @endcode
    %
    % Reference: Gelenbe, E. (1991). "Product-form queueing networks with
    %            negative and positive customers", Journal of Applied Probability
    %
    % Copyright (c) 2012-2026, Imperial College London
    % All rights reserved.
 
    properties
        signalType      % SignalType constant (NEGATIVE, REPLY)
        targetJobClass  % JobClass that this signal is associated with (for REPLY: the class to unblock)
    end
 
    methods
 
        %Constructor
        function self = Signal(model, name, signalType, prio)
            % SIGNAL Create a signal class instance
            %
            % @brief Creates a Signal class for G-network modeling
            % @param model Network model to add the signal class to
            % @param name String identifier for the signal class
            % @param signalType SignalType constant (default: SignalType.NEGATIVE)
            % @param prio Optional priority level (default: 0)
            % @return self Signal instance ready for arrival specification
 
            if nargin < 4
                prio = 0;
            end
            if nargin < 3 || isempty(signalType)
                signalType = SignalType.NEGATIVE;
            end
 
            self@OpenClass(model, name, prio);
            self.signalType = signalType;
            self.targetJobClass = [];
 
            if model.isJavaNative()
                % Replace the OpenClass Java object with a Signal object
                self.obj = jline.lang.Signal(model.obj, name, signalType, prio);
            end
        end
 
        function type = getSignalType(self)
            % GETSIGNALTYPE Get the signal type
            %
            % @return type The SignalType of this signal class
            type = self.signalType;
        end
 
        function self = forJobClass(self, jobClass)
            % FORJOBCLASS Associate this signal with a job class
            %
            % self = FORJOBCLASS(self, jobClass) associates this signal with
            % the specified job class. For REPLY signals, this specifies which
            % job class's servers will be unblocked when this signal arrives.
            %
            % @param jobClass The JobClass to associate with this signal
            % @return self The modified Signal instance (for chaining)
            %
            % Example:
            %   replySignal = Signal(model, 'Reply', SignalType.REPLY).forJobClass(reqClass);
 
            self.targetJobClass = jobClass;
 
            % Also update the JobClass to know about this signal (bidirectional link)
            if ~isempty(jobClass)
                jobClass.replySignalClass = self;
            end
        end
 
        function jobClass = getTargetJobClass(self)
            % GETTARGETJOBCLASS Get the associated job class
            %
            % @return jobClass The JobClass associated with this signal
            jobClass = self.targetJobClass;
        end
 
        function idx = getTargetJobClassIndex(self)
            % GETTARGETJOBCLASSINDEX Get the index of the associated job class
            %
            % @return idx Index of the associated JobClass, or -1 if none
            if isempty(self.targetJobClass)
                idx = -1;
            else
                idx = self.targetJobClass.index;
            end
        end
 
    end
 
end