allow a configured base for cache keys

README

@@ -1106,6 +1106,13 @@ database data in memcached <http://www.danga.com/memcached/>.
 enabled: Set to true to enable. Default false.
 server: a string with the hostname of the memcached server. Can also
 	be an array of hostnames, if you've got more than one server.
+base: memcached uses key-value pairs to store data. We build long,
+      funny-looking keys to make sure we don't have any conflicts. The
+      base of the key is usually a simplified version of the site name
+      (like "Identi.ca" => "identica"), but you can overwrite this if
+      you need to. You can safely ignore it if you only have one
+      Laconica site using your memcached server.
+port: Port to connect to; defaults to 11211.
 
 sphinx
 ------

lib/common.php

@@ -152,6 +152,7 @@ $config =
         'memcached' =>
         array('enabled' => false,
               'server' => 'localhost',
+              'base' => null,
               'port' => 11211),
  		'ping' =>
         array('notify' => array()),

lib/util.php

@@ -1322,7 +1322,13 @@ function common_session_token()
 
 function common_cache_key($extra)
 {
-    return 'laconica:' . common_keyize(common_config('site', 'name')) . ':' . $extra;
+    $base_key = common_config('memcached', 'base');
+
+    if (empty($base_key)) {
+        $base_key = common_keyize(common_config('site', 'name'));
+    }
+
+    return 'laconica:' . $base_key . ':' . $extra;
 }
 
 function common_keyize($str)