interrupt a TCP-IP callback function in matlab - matlab

Question

Recently wrote code that establishes a connection between two instances of matlab. I can send messages through the TCP-IP connection which will execute code. Now I'm trying to setup the code to be interruptible as I would like to start/stop a function through TCP-IP. Problem though is that sending a second command does nothing until the function is completed. Is there a way to interrupt a TCP-IP callback function?
code:
classdef connectcompstogether<handle
properties
serverIP
clientIP
tcpipServer
tcpipClient
Port = 4000;
bsize = 8;
earlystop
end
methods
function gh = connectcompstogether(~)
% gh.serverIP = '127.0.0.1';
gh.serverIP = 'localhost';
gh.clientIP = '0.0.0.0';
end
function SetupServer(gh)
gh.tcpipServer = tcpip(gh.clientIP,gh.Port,'NetworkRole','Server');
set(gh.tcpipServer,'OutputBufferSize',gh.bsize);
fopen(gh.tcpipServer);
display('Established Connection')
end
function SetupClient(gh)
gh.tcpipClient = tcpip(gh.serverIP,gh.Port,'NetworkRole','Client');
set(gh.tcpipClient, 'InputBufferSize',gh.bsize);
set(gh.tcpipClient, 'BytesAvailableFcnCount',8);
set(gh.tcpipClient, 'BytesAvailableFcnMode','byte');
set(gh.tcpipClient, 'BytesAvailableFcn', #(h,e)gh.recmessage(h,e));
fopen(gh.tcpipClient);
display('Established Connection')
end
function CloseClient(gh)
fclose(gh.tcpipClient);
gh.tcpipClient = [];
end
end
methods
function sendmessage(gh,message)
fwrite(gh.tcpipServer,message,'double');
end
function recmessage(gh,h,e)
Message = fread(gh.tcpipClient,gh.bsize/8,'double');
if Message == 444
gh.Funwithnumbers();
elseif Message == 777
gh.earlystop = 1;
end
end
function Funwithnumbers(gh)
x=1;
while true
if x > 5000, break;end
if gh.earlystop == 1,break;end
x = x+1;
display(x)
end
end
end
end
for ease to understand code.
server
Ser = connectcompstogether;
ser.SetupServer();
ser.sendmessage(333);
Client
cli = connectcompstogether;
cli.SetupClient();
Update:
So after going through the web, I have found out based on this post that the tcpip callback cannot be interrupt. The post was in 2017 which means my 2016a version definitely cannot interrupt a callback.
So An update to my question, Is it possible to start a subprocess in matlab to run the function. I just want to use the callback to start code. If I can start a subprocess from the callback. Than I should be able to free up the main process and use tcpip to start/stop a function on a different computer.
Update 2:
So I tried to utilize parallel processing using the 'spmd' command but the problem still persisted.
function recmessage(gh,h,e)
Message = fread(gh.tcpipClient,gh.bsize/8,'double');
spmd
switch labindex
case 1
if Message == 444
gh.Funwithnumbers();
elseif Message == 777
gh.earlystop = 1;
end
end
end
end

Answer 1

You may use a timer object, which is convenient to delay the execution of some function.
t=timer('ExecutionMode','singleShot', 'StartDelay',0, 'TimerFcn',#myCallback);
start(t);
In this case, the StartDelay is 0, so myCallback will be almost immediately added to the queue of tasks to be processed by Matlab. The execution however will start only after the callback to the tcpip object has been completed. It will block the queue once started, however.
You may try something like:
properties
t=timer('ExecutionMode','singleShot', 'StartDelay',0, 'TimerFcn',#myCallback);
end
function tcpipCallback(gh,tcpObj,~)
message=fread(tcpObj,1,'double');
if message==444
if strcmp(get(t,'Running'),'on')
error('The function is running already');
else
set(gh.t,'UserData',false);
start(gh.t);
end
elseif message==777
set(gh.t,'UserData',true);
end
function myCallback(tObj,~)
ii=0;
while ii<5000
if get(tObj,'UserData'),break,end
ii=ii+1;
pause(.0001); %Pause to interrupt the callback; drawnnow might work too; or perhaps this is not needed at all.
end
end