How to control the events of the main event loop of Qcoreapplication

[Abdu]

I use a Qcoreapplication in the main function of a program. I have a sequence of communicating nodes which is read from a file (line by line). At each line, I call sendHello(src,dst). A simple description of the code is as follows:

file format:
node1 node2
node3 node4
node5 node6

int main()
{
  Qcoreapplication app;
  readfromfile();
  app.exec()
}
readfromfile()
{
  while(!eof())
  sendhello(src,dst),
}
sendHello(src,dst)
{
  // Here exchange different messages (more events)
  sendmsg2(dst,src)
  sendmsg3(src,dst)
}

int main()
{
  Qcoreapplication app;
  readfromfile();
  app.exec()
}
readfromfile()
{
  while(!eof())
  sendhello(src,dst),
}
sendHello(src,dst)
{
  // Here exchange different messages (more events)
  sendmsg2(dst,src)
  sendmsg3(src,dst)
}

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Calling each of this sendHello() by each pair, initiates different exchange of information (different events). I found out that the main loop goes from line to line (from pair to pair) and performs the sendHello for each pair sequentially.

Results I get:

sendHello(node1,node2)
sendHello(node3,node4)
sendmsg2(node2,node1)
sendmsg3(node1,node2)
sendmsg2(node4,node3)
sendmsg3(node2,node4)

I need to execute the events that are contained in each sendHello (sendmsg2 and sendmsg3) before moving to next lines (pairs). I tried to understand how to control the events of the main event loop, and how the middle events are scheduled but I did not.

Results I need:

sendHello(node1,node2)
sendmsg2(node2,node1)
sendmsg3(node1,node2)

sendHello(node3,node4)
sendmsg2(node4,node3)
sendmsg3(node2,node4)

I tried processevents( all events) but it`s not working as required. Don`t know why ?

Thanks in advance

[wysota]

You need to start the event loop before you start reading the nodes. Moreover you can't read the nodes in a while loop because you will block the event loop. You can use QTimer::singleShot() with a 0 timeout to schedule execution of a slot without blocking events. You can read more about similar approaches in the article on [wiki]Keeping the GUI Responsive[/wiki].

[Abdu]

Thank you so much , the article you provided me is very useful and I could solve the problem. Before any long operation , I created an event loop, and the event loop starts execution till it gets a signal (timer with 0 time out) that this long operation is finished.