I'm designing a GUI application in Python (with pyGObject, so GTK). The
application communicates with a remote device (connected through RS232,
but it could be on Internet) to retrieve its status and set/get its
configuration.
When the user press "Start" button, the application starts sending "GET
STATUS" requests to the remote device, waiting its response. When the
response arrives, the GUI widgets are refreshed with the new status. The
"GET STATUS" requests are send at a regular frequency (polling mode).
I thought two split the application in two threads: the GUI main thread
that manages graphical widgets and user interaction; the backend thread
that manages low-level communication.
When the user press Start button (the pressed handler is in the GUI class):
self.comm_active = True
threading.Thread(target=self.comm_thread).start()
The backend thread is:
def comm_thread(self):
while self.comm_active:
self.device.get_status()
GLib.idle_add(self.polling_received)
time.sleep(1)
self.m.close()
self.device.get_status() is blocking. It is executed in backend thread,
so the GUI isn't blocked. self.polling_received() function will be
executed in main thread (thanks to GLib.idle_add), because it will
change widgets properties.
Now the get_stats() of self.comm object:
def get_status(self):
<sending command on the serial port>
<waiting for the response>
<parse response>
self.property1 = <value obtained from parsing>
self.property2 = <value obtained from parsing>
return
And self.polling_received() of GUI class:
def polling_received(self):
txtEntry1.set_text(self.comm.property1)
txtEntry2.set_text(self.comm.property2)
I didn't fully tested this, but it seems it works well. However I have
some concerns, mainly for thread syncronizations.
self.polling_received() is executed in GUI thread and reads properties
(self.comm.property1, ...) that are changed during parsing of responses
in self.comm.get_status() function that is executed in the backend thread.
So the two threads use the same variables/objects without
synchronization. Is this a problem?
What is the best approach to use in my scenario (GUI and backend
communication)?
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