patch to force cyrus to reload its configuration in a more rigorous way

[Simon Matter]

> Before this patch, cyrus was already able to detect a configuration
> file change,
> but only at the end of a connection. And any process waiting for a
> new connection was ignoring the change during the next connection,
> until they have finished.
> In other word, after a configuration change, any waiting process can
> still serve a new
> connection with the old configuration and let the administrator
> believe its change is not
> working.
>
> My patch force cyrmaster to send a SIGHUP to all its children when it
> detect a configuration change:
> - any working process will ignore the SIGHUP when processing a
> connection (what my patch does)
> and at the end of the connection, it will detect the configuration
> change and terminate
> (this is what is doing the original code).
> - any waiting process, will catch the SIGHUP and handle it like SIGALARM
> (what my patch does) and make the process believe its waiting period
> (-T option of imapd command) is expired and then terminate. (like was
> doing the original code)

Hi Alain,

Thanks for the patch, I'll try it out and may include it in my rpms later.
If I understand this correctly one drawback could be that on a heavy
loaded server sending SIGHUP will resuilt in much more newly created
processes after the SIGHUP has been sent. Could that be a problem somehow?

Simon

>
> Here is the patch and also in attachment.
>
> Regards
>
> --- cyrus-imapd-2.3.11/imap/signals.c.orig      2006-11-30
> 18:11:20.000000000 +0100
> +++ cyrus-imapd-2.3.11/imap/signals.c   2008-03-23 17:24:54.000000000
> +0100
> @@ -79,6 +79,12 @@
>         fatal("unable to install signal handler for %d: %m", SIGALRM);
>      }
>
> +    /* ASX: SIGHUP is used to force a configuration reload, and the
> waiting
> +     * period is a privileged moment, so we don't set SA_RESTART */
> +    if (alarm && sigaction(SIGHUP, &action, NULL) < 0) {
> +       fatal("unable to install signal handler for %d: %m", SIGHUP);
> +    }
> +
>  #ifdef SA_RESTART
>      action.sa_flags |= SA_RESTART;
>  #endif
> --- cyrus-imapd-2.3.11/master/master.c.orig     2007-10-10
> 15:59:48.000000000 +0200
> +++ cyrus-imapd-2.3.11/master/master.c  2008-03-23 17:29:33.000000000
> +0100
> @@ -1568,6 +1568,23 @@
>                 syslog(LOG_DEBUG, "init: service %s socket %d pipe %d %d",
>                        Services[i].name, Services[i].socket,
>                        Services[i].stat[0], Services[i].stat[1]);
> +        } else if (Services[i].exec && Services[i].socket) {
> +            /* refresh the old one */
> +            syslog(LOG_DEBUG, "ASX SOMETHING TO DO service %s socket
> %d pipe %d %d %d",
> +                      Services[i].name, Services[i].socket,
> +                      Services[i].stat[0], Services[i].stat[1],
> +                       Services[i].exec ? 1:0);
> +            /* send SIGHUP to all children */
> +            for (j = 0 ; j < child_table_size ; j++ ) {
> +                c = ctable[j];
> +                while (c != NULL) {
> +                    if ((c->si == i) && (c->service_state !=
> SERVICE_STATE_DEAD)) {
> +                        syslog(LOG_DEBUG, "ASX send SIGHUP to %d",
> c->pid);
> +                        kill(c->pid, SIGHUP);
> +                    }
> +                    c = c->next;
> +                }
> +            }
>         }
>      }
>
> --- cyrus-imapd-2.3.11/master/service.c.orig    2007-09-27
> 22:10:39.000000000 +0200
> +++ cyrus-imapd-2.3.11/master/service.c 2008-03-23 17:32:46.000000000
> +0100
> @@ -460,7 +460,12 @@
>                             notify_master(STATUS_FD,
> MASTER_SERVICE_UNAVAILABLE);
>                         service_abort(EX_OSERR);
>                     }
> -               }
> +                } else {
> +                     /* fd >= 0 */
> +                     /* ASX we dont want SIGHUP to disrupt a connection
> +                      * before the end */
> +                     signals_add_handlers(0);
> +                }
>             } else {
>                 /* udp */
>                 struct sockaddr_storage from;
>
>
> --
> Alain Spineux
> aspineux gmail com
> May the sources be with you
> ----
> Cyrus Home Page: http://cyrusimap.web.cmu.edu/
> Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki
> List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html