Major refactoring of queue handlers to support running multiple sites in one daemon.

Key changes:
* Initialization code moved from common.php to StatusNet class;
  can now switch configurations during runtime.
* As a consequence, configuration files must now be idempotent...
  Be careful with constant, function or class definitions.
* Control structure for daemons/QueueManager/QueueHandler has been refactored;
  the run loop is now managed by IoMaster run via scripts/queuedaemon.php
  IoManager subclasses are woken to handle socket input or polling, and may
  cover multiple sites.
* Plugins can implement notice queue handlers more easily by registering a
  QueueHandler class; no more need to add a daemon.

The new QueueDaemon runs from scripts/queuedaemon.php:

* This replaces most of the old *handler.php scripts; they've been refactored
  to the bare handler classes.
* Spawns multiple child processes to spread load; defaults to CPU count on
  Linux and Mac OS X systems, or override with --threads=N
* When multithreaded, child processes are automatically respawned on failure.
* Threads gracefully shut down and restart when passing a soft memory limit
  (defaults to 90% of memory_limit), limiting damage from memory leaks.
* Support for UDP-based monitoring: http://www.gitorious.org/snqmon

Rough control flow diagram:
QueueDaemon -> IoMaster -> IoManager
                           QueueManager [listen or poll] -> QueueHandler
                           XmppManager [ping & keepalive]
                           XmppConfirmManager [poll updates]

Todo:

* Respawning features not currently available running single-threaded.
* When running single-site, configuration changes aren't picked up.
* New sites or config changes affecting queue subscriptions are not yet
  handled without a daemon restart.
* SNMP monitoring output to integrate with general tools (nagios, ganglia)
* Convert XMPP confirmation message sends to use stomp queue instead of polling
* Convert xmppdaemon.php to IoManager?
* Convert Twitter status, friends import polling daemons to IoManager
* Clean up some error reporting and failure modes
* May need to adjust queue priorities for best perf in backlog/flood cases

Detailed code history available in my daemon-work branch:
http://www.gitorious.org/~brion/statusnet/brion-fixes/commits/daemon-work

1 files changed, 18 insertions, 7 deletions

diff --git a/lib/jabber.php b/lib/jabber.php
index a821856a8..1d0bb9423 100644
--- a/lib/jabber.php
+++ b/lib/jabber.php
@@ -86,7 +86,11 @@ class Sharing_XMPP extends XMPPHP_XMPP
 }
 
 /**
- * connect the configured Jabber account to the configured server
+ * Lazy-connect the configured Jabber account to the configured server;
+ * if already opened, the same connection will be returned.
+ *
+ * In a multi-site background process, each site configuration
+ * will get its own connection.
  *
  * @param string $resource Resource to connect (defaults to configured resource)
  *
@@ -95,16 +99,19 @@ class Sharing_XMPP extends XMPPHP_XMPP
 
 function jabber_connect($resource=null)
 {
-    static $conn = null;
-    if (!$conn) {
+    static $connections = array();
+    $site = common_config('site', 'server');
+    if (empty($connections[$site])) {
+        if (empty($resource)) {
+            $resource = common_config('xmpp', 'resource');
+        }
         $conn = new Sharing_XMPP(common_config('xmpp', 'host') ?
                                 common_config('xmpp', 'host') :
                                 common_config('xmpp', 'server'),
                                 common_config('xmpp', 'port'),
                                 common_config('xmpp', 'user'),
                                 common_config('xmpp', 'password'),
-                                ($resource) ? $resource :
-                                common_config('xmpp', 'resource'),
+                                $resource,
                                 common_config('xmpp', 'server'),
                                 common_config('xmpp', 'debug') ?
                                 true : false,
@@ -115,12 +122,16 @@ function jabber_connect($resource=null)
         if (!$conn) {
             return false;
         }
+        $connections[$site] = $conn;
 
         $conn->autoSubscribe();
         $conn->useEncryption(common_config('xmpp', 'encryption'));
 
         try {
-            $conn->connect(true); // true = persistent connection
+            common_log(LOG_INFO, __METHOD__ . ": connecting " .
+                common_config('xmpp', 'user') . '/' . $resource);
+            //$conn->connect(true); // true = persistent connection
+            $conn->connect(); // persistent connections break multisite
         } catch (XMPPHP_Exception $e) {
             common_log(LOG_ERR, $e->getMessage());
             return false;
@@ -128,7 +139,7 @@ function jabber_connect($resource=null)
 
         $conn->processUntil('session_start');
     }
-    return $conn;
+    return $connections[$site];
 }
 
 /**