Bringing Sphinx search support up to code: broken out to a plugin, now supports multiple sites on a single server.

Upgrade notes:
* Index names have changed from hardcoded 'Identica_people' and 'Identica_notices' to use the database name and actual table names. Must reindex.

New events:
* GetSearchEngine to override default search engine class selection from plugins

New scripts:
* gen_config.php generates a sphinx.conf from database configuration (with theoretical support for status_network table, but it doesn't seem to be cleanly queriable right now without knowing the db setup info for that. Needs generalized support.)
* Replaced old sphinx-indexer.sh and sphinx-cron.sh with index_update.php

Other fixes:
* sphinx.conf.sample better matches our live config, skipping unused stopword list and using a more realistic indexer memory limit

Further notes:
* Probably doesn't work right with PostgreSQL yet; Sphinx can pull from PG but the extraction queries currently look like they use some MySQL-specific functions.

plugins/SphinxSearch/scripts/sphinx-utils.php

@@ -0,0 +1,63 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 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/>.
+ */
+
+function sphinx_use_network()
+{
+    return have_option('network');
+}
+
+function sphinx_base()
+{
+    if (have_option('base')) {
+        return get_option_value('base');
+    } else {
+        return "/usr/local/sphinx";
+    }
+}
+
+function sphinx_iterate_sites($callback)
+{
+    if (sphinx_use_network()) {
+        // @fixme this should use, like, some kind of config
+        Status_network::setupDB('localhost', 'statusnet', 'statuspass', 'statusnet');
+        $sn = new Status_network();
+        if (!$sn->find()) {
+            die("Confused... no sites in status_network table or lookup failed.\n");
+        }
+        while ($sn->fetch()) {
+            $callback($sn);
+        }
+    } else {
+        if (preg_match('!^(mysqli?|pgsql)://(.*?):(.*?)@(.*?)/(.*?)$!',
+                common_config('db', 'database'), $matches)) {
+            list(/*all*/, $dbtype, $dbuser, $dbpass, $dbhost, $dbname) = $matches;
+            $sn = (object)array(
+                'sitename' => common_config('site', 'name'),
+                'dbhost' => $dbhost,
+                'dbuser' => $dbuser,
+                'dbpass' => $dbpass,
+                'dbname' => $dbname);
+            $callback($sn);
+        } else {
+            print "Unrecognized database configuration string in config.php\n";
+            exit(1);
+        }
+    }
+}
+