Queue handlers for XMPP individual & firehose output now send their XML stanzas
to another output queue instead of connecting directly to the chat server. This
lets us have as many general processing threads as we need, while all actual
XMPP input and output go through a single daemon with a single connection open.
This avoids problems with multiple connected resources:
* multiple windows shown in some chat clients (psi, gajim, kopete)
* extra load on server
* incoming message delivery forwarding issues
Database changes:
* queue_item drops 'notice_id' in favor of a 'frame' blob.
This is based on Craig Andrews' work branch to generalize queues to take any
object, but conservatively leaving out the serialization for now.
Table updater (preserves any existing queued items) in db/rc3to09.sql
Code changes to watch out for:
* Queue handlers should now define a handle() method instead of handle_notice()
* QueueDaemon and XmppDaemon now share common i/o (IoMaster) and respawning
thread management (RespawningDaemon) infrastructure.
* The polling XmppConfirmManager has been dropped, as the message is queued
directly when saving IM settings.
* Enable $config['queue']['debug_memory'] to output current memory usage at
each run through the event loop to watch for memory leaks
To do:
* Adapt XMPP i/o to component connection mode for multi-site support.
* XMPP input can also be broken out to a queue, which would allow the actual
notice save etc to be handled by general queue threads.
* Make sure there are no problems with simply pushing serialized Notice objects
to queues.
* Find a way to improve interactive performance of the database-backed queue
handler; polling is pretty painful to XMPP.
* Possibly redo the way QueueHandlers are injected into a QueueManager. The
grouping used to split out the XMPP output queue is a bit awkward.
Extended subscription table indexes for subscriber and subscribed to include the created field, which is used to sort for display. This lets us skip a filesort and do the join much more efficiently.
Alter table from 08to09.sql needs to be run manually (though no ill effects if you forget other than not getting the perf improvement).
fave_user_id_idx index changed from (user_id) to (user_id,modified), so the timestamp ordering can be done straight from the index while we're looking up the user's notices.
Added to 08to09.sql and 08to09_pg.sql; may need to be run manually by folks doing development.
(No harm if you don't update it, the favorites tab/rss feed will just stay inefficent.)
