Re: [Evolution] IMAP scanning gets stuck

[Jeffrey Stedfast <fejj ximian com>]

On Fri, 2001-11-23 at 20:10, Ujwal S. Sathyam wrote:
[snip]
> > Anyways, we already set the socket to O_NONBLOCK before we connect() and
> > do a select() on the socket after afaik, so this doesn't seem to work on
> > linux systems.
>
> The timeout on a blocking connect() in Linux can vary depending on the
> destination IP address. I have seen timouts of 14 minutes for
> destination outside the LAN. In my code, I usually set the socket to
> O_NONBLOCK with fcntl() before doing the connect. I then use poll with a
> 10 second timeout (I have a pretty busy server), and that has always
> worked well for me. 

This is basically what we are currently doing, but according to you it's
not working. We *do* set the socket to O_NONBLOCK with an fcntl() call
and then call connect() and then select() on the socket and a cancel_fd
which is basically the same as polling on the socket while also allowing
user-intervention.

as seen here:

        flags = fcntl (fd, F_GETFL);
        fcntl (fd, F_SETFL, flags | O_NONBLOCK);
        
        ret = connect (fd, (struct sockaddr *)&sin, sizeof (sin));
        if (ret == 0) {
                fcntl (fd, F_SETFL, flags);
                return fd;
        }
        
        if (errno != EINPROGRESS) {
                close (fd);
                return -1;
        }
        
        FD_ZERO (&rdset);
        FD_ZERO (&wrset);
        FD_SET (fd, &wrset);
        FD_SET (cancel_fd, &rdset);
        fdmax = MAX (fd, cancel_fd) + 1;
        tv.tv_usec = 0;
        tv.tv_sec = 60 * 4;
        
        if (select (fdmax, &rdset, &wrset, 0, &tv) <= 0) {
                close (fd);
                errno = ETIMEDOUT;
                return -1;
        }

> > Also, I seem to recall reading in some man page or another that the
> > linux connect() always blocks anyway? I could have sworn I read this a
> > while back after noticing that winsock was able to do non-blocking
> > connect()'s.
>
> If you use O_NONBLOCK correctly, connect() can be made non-blocking. As
> I said, that is what I do in my code.

yes, and we do...but it seems to be not working (by your account at
least).

Jeff