Stop code execution with a callback

Question

Riccardo Barilli 2020-7-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/571642-stop-code-execution-with-a-callback

回答： Brian Harris 2023-4-4

I am integrating cplex in app designer to perfom optimizations. Considering the problem dimensions, sometimes cplex needs a lot of time in order to find a solution. I would like to allow the user to stop the calculation if it seems to be stacked.

I noticed that the command Ctrl+C from the keyboard is able to stop cplex. Cplex is called thanks to a class (then I cannot insert breakpoints inside) and it acts as a function but Ctrl+C does not brake the execution but it asks to cplex to interrupt the optimization finding a partial optimum point.

From app designer the user does not have access to the command window, then is it possible to simulate the command within a callback?

I found this code within the forum. Actually, it works but it depends on the fact that, before starting a function, I must start the timer and then after 4 seconds it executes the command Ctrl+C in the same way I would do from the keyboard.

t = timer('TimerFcn','com.mathworks.mde.cmdwin.CmdWinMLIF.getInstance().processKeyFromC(2,67,''C'')','StartDelay',4);
start(t);

How can I insert this inside a callbacks and how can I invoke the callback during a ongoing execution? I would like to queue cplex in order to execute Ctrl+C and see that Matlab stops the running.

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Answer 1

Image Analyst 2020-7-28

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https://ww2.mathworks.cn/matlabcentral/answers/571642-stop-code-execution-with-a-callback#answer_471871

See attached demo. It's for GUIDE but you can use the same concept for App Designer.

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Riccardo Barilli 2020-7-31

在 MATLAB Online 中打开

I can't do that because I cannot insert code inside Cplex.

Actually I resolve the problem this way:

  t=timer('TimerFcn',...
                strcat(...
                'drawnow; ',...
                'global curPopupCplex;',...
                'disp(''++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++''); ',...
                'disp(sprintf(''Stop Cplex? %s'',string(curPopupCplex.StopFlag))); ',...
                'if curPopupCplex.StopFlag; ',...
                    'disp(''Stopping CPLEX ...''); ',...
                    'com.mathworks.mde.cmdwin.CmdWinMLIF.getInstance().processKeyFromC(2,67,''C'');',...
                'end;',...
                'disp(''++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++''); '),...
                'StartDelay',300,'Period',120,'ExecutionMode','fixedRate');
            start(t);

A timer that executes drawnow and resolve the callback queue in order to execute the command that reproduces the Ctrl+C.

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Answer 2

Brian Harris 2023-4-4

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https://ww2.mathworks.cn/matlabcentral/answers/571642-stop-code-execution-with-a-callback#answer_1208459

在 MATLAB Online 中打开

If you are ok with the limitations of a parfeval call (need parallel processing toolbox, any graphics produced by the calling function are surpressed, ...) you can easily cancel the call.

% This runs in a parallel worker so does not block the main/calling thread
% note: it will block on a call to fetchOutputs(f)
f = parfeval(backgroundPool,@pause,0,Inf);
% when button is pressed, or other callback is executed, call this:
cancel(f);