[pygtk] Non-blocking subprocess.Popen stop GUI

[John Finlay]

Bou Baris wrote:
>> Instead of using select() use gobject.io_add_watch() on proc.stdout to
>> register a callback function that is used to read the % and set the progress
>> bar.
>>     
>
> I've modified my code to test gobject.io_add_watch()
> I expect that test_io_watch() print in console line readed from proc.stdout
> But i see nothing: look like a blocking behaviour (as when use Popen
> without use select)
> If I stop program with CTRL-C, now I see the output to console/terminal
>
>
>   def test_io_watch(self, file, condition):
>         print str(file.readline())
>         return True
>
>   def mkv_dts_extraction(self,dtstrack,pgbar=None):
>
>         command=['mkvextract', \
>                     'tracks', \
>                     self.INPUTFILE, \
>                     dtstrack + ':' + self.TEMP_DTSFILENAME]
>
>         proc=subprocess.Popen(command,stdout=subprocess.PIPE)
>
>         outfile=proc.stdout
>         outfd=outfile.fileno()
>         file_flags = fcntl.fcntl(outfd, fcntl.F_GETFL)
>         fcntl.fcntl(outfd, fcntl.F_SETFL, file_flags | os.O_NDELAY)
>
>         gobject.io_add_watch(proc.stdout,gobject.IO_IN |
> gobject.IO_HUP,self.test_io_watch)
>
>         err = proc.wait()
>
>         return True
>   
I think this is due to mkvextract not flushing its output because it's 
not connected to a tty. Try using a pty in between to fool mkvextract. 
Something like:

from_mkve, to me = pty.openpty()
to_me = os.fdopen(to_me, 'r')
file_flags = fcntl.fcntl(to_me, fcntl.F_GETFL)
fcntl.fcntl(to_me, fcntl.F_SETFL, file_flags|os.O_NDELAY)
proc = subprocess.Popen(command, stdout=from_mkve)
gobject.io_add_watch(to_me, gobject.IO_IN|gobject.IO_HUP, 
self.test_io_watch)

John