Re: g_spawn_async_with_pipes and g_io_add_watch problems

[Hubert Sokolowski <h sokolowski wsisiz edu pl>]

On Fri, 3 Dec 2004 09:17:03 -0500
Tristan Van Berkom <tristan van berkom gmail com> wrote:

> On Fri, 3 Dec 2004 13:47:19 +0100 (CET), Hubert Sokolowski
> <h sokolowski wsisiz edu pl> wrote:
> > Hi!
> >
> > I execute from my program dd and gzip both using
> > g_spawn_async_with_pipes.
> > dd reads from a file and outputs data to stdout. stdout from dd is
> > added
> > with g_io_add_watch. stdout from gzip is also added with
> > g_io_add_watch.
> > in function that reads from dd I have a loop that reads whole data.
> > in that function I execute
> >  while (gtk_events_pending ())
> >         gtk_main_iteration ();
> > so my UI is refreshed and main loop is iterated.
> > but after few iterations in my loop my program locks on writing to
> > channel
> > that is connected to stdin of gzip.
> > how to fix this problem so the function that reads from stdout gzip
> > is
> > executed.
> > I was trying to return from the first function that reads from dd
> > after
> > reading one block of data (not to the end of the data) but there was
> > no
> > difference.
> >
> > I probably do something wrong. how to connect this two programs
> > together?
>
> So the problem is that your main process is blocking on write to
> gzip's stdin
> while it should be reading from gzip's stdout right ?
my main process was locking on writing to gzip's stdin or on reading
from gzip's stdout. this was because I wasn't checking if I can write to
gzip's stdin.

> I would sugest simply "not blocking" on write to gzip's stdin.
> (i.e. make sure all your reads/writes are one byte at a time and
> use select() to check if the descriptor is ready or not, dont just
> read/write).
can I use g_io_channel_get_buffer_condition instead of select?

thanks for your advice

-- 
Hubert Sokolowski