From 0e852def6ae5aa529cca0aef1187152fb5a880be Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@pobox.com>
Date: Thu, 21 Jan 2010 16:42:50 -0800
Subject: XMPP queued output & initial retooling of DB queue manager to support
 non-Notice objects.

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.
---
 lib/xmppoutqueuehandler.php | 55 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 lib/xmppoutqueuehandler.php

(limited to 'lib/xmppoutqueuehandler.php')

diff --git a/lib/xmppoutqueuehandler.php b/lib/xmppoutqueuehandler.php
new file mode 100644
index 000000000..2afa260f1
--- /dev/null
+++ b/lib/xmppoutqueuehandler.php
@@ -0,0 +1,55 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * Queue handler for pre-processed outgoing XMPP messages.
+ * Formatted XML stanzas will have been pushed into the queue
+ * via the Queued_XMPP connection proxy, probably from some
+ * other queue processor.
+ *
+ * Here, the XML stanzas are simply pulled out of the queue and
+ * pushed out over the wire; an XmppManager is needed to set up
+ * and maintain the actual server connection.
+ *
+ * This queue will be run via XmppDaemon rather than QueueDaemon.
+ *
+ * @author Brion Vibber <brion@status.net>
+ */
+class XmppOutQueueHandler extends QueueHandler
+{
+    function transport() {
+        return 'xmppout';
+    }
+
+    /**
+     * Take a previously-queued XMPP stanza and send it out ot the server.
+     * @param string $msg
+     * @return boolean true on success
+     */
+    function handle($msg)
+    {
+        assert(is_string($msg));
+
+        $xmpp = XmppManager::get();
+        $ok = $xmpp->send($msg);
+
+        return $ok;
+    }
+}
+
-- 
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