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/index_update.php

@@ -0,0 +1,61 @@
+#!/usr/bin/env php
+<?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/>.
+ */
+
+define('INSTALLDIR', realpath(dirname(__FILE__) . '/../../..'));
+
+$longoptions = array('base=', 'network');
+
+$helptext = <<<END_OF_TRIM_HELP
+Runs Sphinx search indexer.
+    --rotate             Have Sphinx run index update in background and
+                         rotate updated indexes into place as they finish.
+    --base               Base dir to Sphinx install
+                         (default /usr/local)
+    --network            Use status_network global config table for site list
+                         (non-functional at present)
+
+
+END_OF_TRIM_HELP;
+
+require_once INSTALLDIR . '/scripts/commandline.inc';
+require dirname(__FILE__) . '/sphinx-utils.php';
+
+sphinx_iterate_sites('sphinx_index_update');
+
+function sphinx_index_update($sn)
+{
+    $base = sphinx_base();
+    
+    $baseIndexes = array('notice', 'profile');
+    $params = array();
+    
+    if (have_option('rotate')) {
+        $params[] = '--rotate';
+    }
+    foreach ($baseIndexes as $index) {
+        $params[] = "{$sn->dbname}_{$index}";
+    }
+    
+    $params = implode(' ', $params);
+    $cmd = "$base/bin/indexer --config $base/etc/sphinx.conf $params";
+    
+    print "$cmd\n";
+    system($cmd);
+}