SimEvents access class/object in MATLAB

I am trying to build a model of an OS scheduler in SimEvents. Using MATLAB code, I created a class to represent a Task that describes the behavior of the task (e.g. run for x steps, perform I/O for y steps, repeat m steps n times, and so on. I'm really stuck trying to figure out how to integrate this into the SimEvents environment.

For example, I see where I can use an entity generator, and use a MATLAB function block to return the delta-T for the next event generation. For example, the example of random generation works great.

function dt = getDT( )
   dt = rand(1,1);
end

What I'd really like to do is to call my TaskList object that returns the time a new process is admitted to the system:

function dt = getDT()
  dt = task_list.getNextStart();
end

But, I cannot seem to get the SimEvents system to be able to see the task_list object in the base workspace. I've tried using the ports and data manager and tag the variable as a parameter, but its not one of the known types and nothing I've tried seems to work.

Any advice?

Answer 1

[Altaïr]

Hey @Thomas Briggs,

An object for a custom class can be created and its corresponding method can be called within the MATLAB action section of the entity generator. Below is a sample definition of a TaskList class to illustrate this approach:

classdef TaskList
    properties
        % Example property to store task start times
        taskStartTimes
        currentIndex
    end
    
    methods
        function obj = TaskList()
            % Constructor to initialize the task list
            % Example: Initialize with some dummy start times
            obj.taskStartTimes = [0.1,0.2,0.3,0.4,0.5]; % Example start times
            obj.currentIndex = 1; % Start at the first task
        end
        
        function [obj, dt] = getNextStart(obj)
            % Method to get the next start time delta
            if obj.currentIndex <= length(obj.taskStartTimes)
                dt = obj.taskStartTimes(obj.currentIndex);
                obj.currentIndex = obj.currentIndex + 1; % Move to the next task
            else
                dt = inf; % No more tasks, return infinity or some sentinel value
            end
        end
    end
end

The getNextStart method provides the interval for the next entity generation. In the entity generator, set the Generation method to Time-Based and the Time source to MATLAB action. This enables the Intergeneration time action section, where the following code can be used to create a persistent TaskList object and call the getNextStart method:

persistent task_list;
if isempty(task_list)
   % Initialize your task_list object here
   task_list = TaskList(); % Assuming TaskList is your class
end
[task_list, dt] = task_list.getNextStart();

With this setup, the entity intergeneration times will correspond to the values specified in the taskStartTimes array.

For further information, the Specify Intergeneration Times for Entities documentation page can be accessed using the command below:

web(fullfile(docroot, 'simevents/ug/specifying-intergeneration-times-for-entities.html'))