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, 273 insertions, 0 deletions

diff --git a/lib/xmppmanager.php b/lib/xmppmanager.php
new file mode 100644
index 000000000..9662e97d1
--- /dev/null
+++ b/lib/xmppmanager.php
@@ -0,0 +1,273 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2008, 2009, 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/>.
+ */
+
+if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
+
+/**
+ * XMPP background connection manager for XMPP-using queue handlers,
+ * allowing them to send outgoing messages on the right connection.
+ *
+ * Input is handled during socket select loop, keepalive pings during idle.
+ * Any incoming messages will be forwarded to the main XmppDaemon process,
+ * which handles direct user interaction.
+ *
+ * In a multi-site queuedaemon.php run, one connection will be instantiated
+ * for each site being handled by the current process that has XMPP enabled.
+ */
+
+class XmppManager extends IoManager
+{
+    protected $site = null;
+    protected $pingid = 0;
+    protected $lastping = null;
+
+    static protected $singletons = array();
+    
+    const PING_INTERVAL = 120;
+
+    /**
+     * Fetch the singleton XmppManager for the current site.
+     * @return mixed XmppManager, or false if unneeded
+     */
+    public static function get()
+    {
+        if (common_config('xmpp', 'enabled')) {
+            $site = common_config('site', 'server');
+            if (empty(self::$singletons[$site])) {
+                self::$singletons[$site] = new XmppManager();
+            }
+            return self::$singletons[$site];
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * Tell the i/o master we need one instance for each supporting site
+     * being handled in this process.
+     */
+    public static function multiSite()
+    {
+        return IoManager::INSTANCE_PER_SITE;
+    }
+
+    function __construct()
+    {
+        $this->site = common_config('site', 'server');
+    }
+
+    /**
+     * Initialize connection to server.
+     * @return boolean true on success
+     */
+    public function start($master)
+    {
+        parent::start($master);
+        $this->switchSite();
+
+        require_once "lib/jabber.php";
+
+        # Low priority; we don't want to receive messages
+
+        common_log(LOG_INFO, "INITIALIZE");
+        $this->conn = jabber_connect($this->resource());
+
+        if (empty($this->conn)) {
+            common_log(LOG_ERR, "Couldn't connect to server.");
+            return false;
+        }
+
+        $this->conn->addEventHandler('message', 'forward_message', $this);
+        $this->conn->addEventHandler('reconnect', 'handle_reconnect', $this);
+        $this->conn->setReconnectTimeout(600);
+        jabber_send_presence("Send me a message to post a notice", 'available', null, 'available', -1);
+
+        return !is_null($this->conn);
+    }
+
+    /**
+     * Message pump is triggered on socket input, so we only need an idle()
+     * call often enough to trigger our outgoing pings.
+     */
+    function timeout()
+    {
+        return self::PING_INTERVAL;
+    }
+
+    /**
+     * Lists the XMPP connection socket to allow i/o master to wake
+     * when input comes in here as well as from the queue source.
+     *
+     * @return array of resources
+     */
+    public function getSockets()
+    {
+        return array($this->conn->getSocket());
+    }
+
+    /**
+     * Process XMPP events that have come in over the wire.
+     * Side effects: may switch site configuration
+     * @fixme may kill process on XMPP error
+     * @param resource $socket
+     */
+    public function handleInput($socket)
+    {
+        $this->switchSite();
+
+        # Process the queue for as long as needed
+        try {
+            if ($this->conn) {
+                assert($socket === $this->conn->getSocket());
+                
+                common_log(LOG_DEBUG, "Servicing the XMPP queue.");
+                $this->stats('xmpp_process');
+                $this->conn->processTime(0);
+            }
+        } catch (XMPPHP_Exception $e) {
+            common_log(LOG_ERR, "Got an XMPPHP_Exception: " . $e->getMessage());
+            die($e->getMessage());
+        }
+    }
+
+    /**
+     * Idle processing for io manager's execution loop.
+     * Send keepalive pings to server.
+     *
+     * Side effect: kills process on exception from XMPP library.
+     *
+     * @fixme non-dying error handling
+     */
+    public function idle($timeout=0)
+    {
+        if ($this->conn) {
+            $now = time();
+            if (empty($this->lastping) || $now - $this->lastping > self::PING_INTERVAL) {
+                $this->switchSite();
+                try {
+                    $this->sendPing();
+                    $this->lastping = $now;
+                } catch (XMPPHP_Exception $e) {
+                    common_log(LOG_ERR, "Got an XMPPHP_Exception: " . $e->getMessage());
+                    die($e->getMessage());
+                }
+            }
+        }
+    }
+
+    /**
+     * Send a keepalive ping to the XMPP server.
+     */
+    protected function sendPing()
+    {
+        $jid = jabber_daemon_address().'/'.$this->resource();
+        $server = common_config('xmpp', 'server');
+
+        if (!isset($this->pingid)) {
+            $this->pingid = 0;
+        } else {
+            $this->pingid++;
+        }
+
+        common_log(LOG_DEBUG, "Sending ping #{$this->pingid}");
+
+        $this->conn->send("<iq from='{$jid}' to='{$server}' id='ping_{$this->pingid}' type='get'><ping xmlns='urn:xmpp:ping'/></iq>");
+    }
+
+    /**
+     * Callback for Jabber reconnect event
+     * @param $pl
+     */
+    function handle_reconnect(&$pl)
+    {
+        common_log(LOG_NOTICE, 'XMPP reconnected');
+
+        $this->conn->processUntil('session_start');
+        $this->conn->presence(null, 'available', null, 'available', -1);
+    }
+
+    /**
+     * Callback for Jabber message event.
+     *
+     * This connection handles output; if we get a message straight to us,
+     * forward it on to our XmppDaemon listener for processing.
+     *
+     * @param $pl
+     */
+    function forward_message(&$pl)
+    {
+        if ($pl['type'] != 'chat') {
+            common_log(LOG_DEBUG, 'Ignoring message of type ' . $pl['type'] . ' from ' . $pl['from']);
+            return;
+        }
+        $listener = $this->listener();
+        if (strtolower($listener) == strtolower($pl['from'])) {
+            common_log(LOG_WARNING, 'Ignoring loop message.');
+            return;
+        }
+        common_log(LOG_INFO, 'Forwarding message from ' . $pl['from'] . ' to ' . $listener);
+        $this->conn->message($this->listener(), $pl['body'], 'chat', null, $this->ofrom($pl['from']));
+    }
+
+    /**
+     * Build an <addresses> block with an ofrom entry for forwarded messages
+     *
+     * @param string $from Jabber ID of original sender
+     * @return string XML fragment
+     */
+    protected function ofrom($from)
+    {
+        $address = "<addresses xmlns='http://jabber.org/protocol/address'>\n";
+        $address .= "<address type='ofrom' jid='$from' />\n";
+        $address .= "</addresses>\n";
+        return $address;
+    }
+
+    /**
+     * Build the complete JID of the XmppDaemon process which
+     * handles primary XMPP input for this site.
+     *
+     * @return string Jabber ID
+     */
+    protected function listener()
+    {
+        if (common_config('xmpp', 'listener')) {
+            return common_config('xmpp', 'listener');
+        } else {
+            return jabber_daemon_address() . '/' . common_config('xmpp','resource') . 'daemon';
+        }
+    }
+
+    protected function resource()
+    {
+        return 'queue' . posix_getpid(); // @fixme PIDs won't be host-unique
+    }
+
+    /**
+     * Make sure we're on the right site configuration
+     */
+    protected function switchSite()
+    {
+        if ($this->site != common_config('site', 'server')) {
+            common_log(LOG_DEBUG, __METHOD__ . ": switching to site $this->site");
+            $this->stats('switch');
+            StatusNet::init($this->site);
+        }
+    }
+}