Weird problems: C library programs crashing in combination with GTK UI

[vijayasarathy setsindia net]

Hi all,


I am giving a UI for a library which has been developed in core ANSI C.
The library calls a function close to 1000 times and is highly voluminous
in terms of space and time. I want to call this function 1000 times from
my UI.

I have made a dll file out of the C library, and I am using glade for GTK
front end. I have written ANSI C code snippets to check if the library
functions are working, and they appear to be working very well without any
problems.

While I told that this function call from the library takes a lot of time,
I have a progress bar in my UI, and while runnning this library function,
my progress bar keeps updating the fraction of work done by that
library[the fraction is actually computed by the C library function,
written into a file, and the timeout function keeps reading fraction value
from the same file periodically and updates its fraction].

For this I have written a time out function which keeps updating fraction
regularly in the progress bar.

So, I call this time out function first, and immediately I call this C
library function, and then followed by:

while (gtk_events_pending ())
{
        g_print("[.]");
        gtk_main_iteration ();
}

so that the timeout function doesnt have to blocked until this big
function is over, and it can keep updating fraction.

I am now facing really weird problems here.

1. My time out function is NOT BEING CALLED AT ALL. I am inserting a few
g_prints in the time out function, and I see nothing on the console.
Moreover, no updates are happening to progress bar fraction. Only after
fraction reaches 0.99, progress bar time out function is called.
2. My C library function crashes if I make changes to the timeout function
or the callback function. Windows is full of mysteries and I dont even
know why it crashed. When I include a g_print somewhere in the callback
function or timeout function, it starts working, and then suddenly stops
working

I am using windows MingGw-Msys-GTK2.0-glade combination for writing my
apps in windows.

Pseudo code for my call back function [for some button which will initiate
action] is as follows:

/***************CALL BACK FUNCTION CODE SNIPPET ***********************/
g_timeout_add(1500,progress_timeout,progressbarwidget);

f1();//THE BIG FUNCTION WHICH WILL RUN CLOSE TO A FEW HOURS

while (gtk_events_pending ())
{
        g_print("[.]");
        gtk_main_iteration ();
}//THIS SO THAT THE TIME OUT FUNCTION WILL BE ABLE TO CALL ITSELF

/****************END CALL BACK FUNCTION CODE SNIPPET**********************/


/****************TIME OUT FUNCTION *************************************/
static gboolean progress_timeout( gpointer pbar)
{
        /*
        1. Open file frac.v in read mode.
        2. Read fraction.
        3. Convert read fraction into double.
        4. Update progress bar with fraction.
        5. If fraction >=0.99, then deem that work is complete, so return true to
g_timeout_add.
        */
        FILE *fp;
        gchar *buffer;
        gdouble fraction = 0.0;
        //1. Open file frac.v in read mode.

        fp = fopen("frac.v","r");
        if(fp==NULL)
        {
                displayError("Unable to update Progress bar.\n");
                return FALSE;//Stop updating
        }//End if fp==NULL

        /*
        Buffer will hold the fraction read from file. Fraction is of precision 5,
and will be between 0 and 1. So, size = 1[0//1]+1['.']+5[precision 5]
+1[EOS] = 8
        */
        buffer = (gchar *)g_malloc0(8*sizeof(gchar));
        //2. Read first line into buffer
        fgets(buffer,8,fp);
        fclose(fp);
        //Buffer contains fraction.

        //3. Convert read fraction into double[until end of buffer].
        fraction = strtod(buffer,NULL);

        //4. Update progress bar with fraction.
        gtk_progress_bar_set_fraction (GTK_PROGRESS_BAR (pbar), fraction);

        //Free memory
        g_free(buffer);

        //5. If fraction >=0.99, then deem that work is complete, so return true
to g_timeout_add.
        if(fraction>=0.99)//If work is complete.
        {

                return FALSE;//Stop updating.
        }
        else//If work is not complete.
        {
                g_print("Time out function called");
                return TRUE;
        }
}//End function progress_timeout




/******************END TIME OUT FUNCTION *********************************/


1. Why should my C library function [which otherwise is doing very well]
crash just because I made some print changes in callback and time out ?

2. Since my timeout function has file I/O operations, is it that file I/Os
are still blocked even if I insert the gtk_main_iteration() call inside
while loop as I have indicated ?



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