Programming

If I had to recieve data through message queue in child process...then its okay....my code is working fine........

what should I do to make make my child to collect data through message queue continously.........
length of data to be recieved and send is fixed.......because my application is like that .....it sends or recieves fixed length data, so no need to check length ........

plz tell me in steps what steps should I follow????

sir, I am modifing my fist line of my previous post.............

If I had to recieve data through message queue in child process only once....then its okay....my code is working fine........

put a while loop round it

Code:

while (1)
{
    read msg queue
    write pipe
}

now facing another problem............
Now I am able to send and recieve messages on message queue...........
but if my process goes idle for some tome 10-20 minutes then its blocking and after such duration I am not able to recieve messages which are in message queue bufffer........
what to do sir??????

Is the main process still sitting in select? Ie, waiting for input on the pipe?

Use a debugger and attach to the process to see where it is.

You could also do strace of the process..

strace -ppid

Are all reads and writes passing the correct amount of data, you may get partial reads/writes as the pipe becomes full.

I recommend putting a loop round each read and write so if the API returns less, you go back for the remainder you are expecting.

Code:

while (len)
{
    int i=read(fd,p,len);
    if (i < 0) { perror("read"); break; }
    if (i == 0) break;
    p+=i;
    len-=i;
}

and

Code:

while (len)
{
    int i=write(fd,p,len);
    if (i < 0) { perror("write"); break; }
    if (i == 0) break;
    p+=i;
    len-=i;
}