Best way to shutdown ROS when used with MATLAB Compiler

I have a basic question regarding how to use the robotics.ros library in an application that is compiled using MATLAB Compiler.

The overall structure of my application looks like this:

rosinit(...)            % Connect to an external ROS master.
pub = rospublisher(...) % Declare publisher to be used in while loop.
while 1                 % Run this loop until user press Ctrl+C
  ...
  send(pub,msg)         % Publish data in while loop.
end
rosshutdown             % NEVER REACHED

As I have tried to illustrate in the above code, I'm entering an infinite loop where data is simply published until the user closes the application using Ctrl+C. This means that the rosshutdown command is never reached resulting in the node staying alive.

My question is: What is the best way to shutdown ROS in this scenario?

If the node is not shutdown properly, I receive the following error message:

 A node called /some_node has already registered with the ROS master 
 http://localhost:11311. Try creating a node with a different name.

 robotics:ros:node:NodeNameExists

I have tried to register an onCleanup function, but that does not seem to be supported by the MATLAB Compiler.

Answer 1

[Cam Salzberger]

Hello Andreas,

Instead of an infinite loop, an alternative design pattern you could try is to run the publishing within a timer callback. This would push the computation and publishing to the background, and allow the rest of the program to continue running. Then you can simply put in a pause statement so that the main program continues to idle until you hit Enter. Something like:

function myMainFunction
    rosinit(...)
    pub = rospublisher(...);
    t = timer;
    t.Period = 0.1;    % Pick appropriate publish rate
    t.TimerFcn = @myTimerCallback;
    start(t)
    pause
    stop(t)
    delete(t)
    rosshutdown
end

function myTimerCallback(~, ~)
    ...
    send(pub, msg)
end

-Cam