Re: How to handle long I/O operations

["Tara M" <learfox furry ao net>]

On Tue, 14 Aug 2001 18:10:17 +0200, Jean-Christophe Berthon said:

> Hello,
>  
>  First a big thanks to Markus, Tara and Luciano for their help. It helped me
>  understand better the timeout, idle and "threads" in Gtk.
>  But like Markus mentioned it, it will be hard for me to use the timeout as I
>  have no clue of how long the computation will take (it's kind of heavy
>  mathematical computation involving matrix and "3D" representation of
>  thousands of points in a geodesic origin, it can take a few hours up to a
>  few days! Depending on the precision the user ask, and how many points are
>  involved) So if my calculation exceed the timeout period I guess I will got
>  a crash (if it behaves like in a real-time environment) So I guess the
>  gtk_idle_add looks more appropriate.
>  And thanks Tara for the warning for the "thread safe" problem that might
>  occur while using gtk_main_iteration.


We try our best. :)

There's a few things I wanted to PS to what was talked about
earlier.

I put our design to the test again and found some issues.

I recommend using GTK+ timeouts and when you use them I
recommend that you design your main GTK+ job management handler
as follows (it's quite efficient and works for long calculations):


guint toid;     /* Might want to make this a local and pass it around. */

gint manage_tocb(gpointer data)
{
        /* Manage jobs here. */





        /* Schedual another timeout for this same function. */
        toid = gtk_timeout_add(
            50,
            (GtkFunction)manage_tocb,
            NULL
        );
        /* Return FALSE so this function is not called again for
         * the same timeout id. But don't worry, we already schedualed
         * a NEW timeout id to call this function again in 50 ms.
         */
        return(FALSE);
}

int main(int argc, char *argv[])
{
        /* ... */

        toid = gtk_timeout_add(
            50,
            (GtkFunction)manage_tocb,
            NULL
        );

        /* ... */
}



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--
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