Control channel for queue daemons to request graceful shutdown, restart, or update to listen to a newly added or reconfigured site.

queuectl.php --update -s<site>
  queuectl.php --stop
  queuectl.php --restart

Default control channel is /topic/statusnet-control. For external utilities to send a site update ping direct to the queue server, connect via Stomp and send a message formatted thus:

  update:<nickname>

(Nickname here, *not* server hostname! The rest of the queues will be updated to use nicknames later.)

Note that all currently-connected queue daemons will get these notifications, including both queuedaemon.php and xmppdaemon.php. (XMPP will ignore site update requests for sites that it's not handling.)

Limitations:
* only implemented for stomp queue manager so far
* --update may not yet handle a changed server name properly
* --restart won't reload PHP code files that were already loaded at startup. Still need to stop and restart the daemons from 'outside' when updating code base.

scripts/queuedaemon.php

@@ -115,7 +115,7 @@ class QueueDaemon extends SpawningDaemon
 
         $this->log(LOG_INFO, 'terminating normally');
 
-        return true;
+        return $master->respawn ? self::EXIT_RESTART : self::EXIT_SHUTDOWN;
     }
 }