OStatus/FeedSub: tweaked PuSH feed garbage collection so other plugins can declare usage of a low-level feed or an OStatus profile besides profile subscriptions & group memberships.

SubMirror: redid add-mirror frontend to accept a feed URL, then pass that on to OStatus, instead of pulling from your subscriptions.
Profile: tweaked subscriberCount() so it doesn't subtract 1 for foreign profiles who aren't subscribed to themselves; instead excludes the self-subscription in the count query.
Memcached_DataObject: tweak to avoid extra error spew in the DB error raising

Work in progress: tweaking feedsub garbage collection so we can count other uses

plugins/OStatus/OStatusPlugin.php

@@ -479,6 +479,24 @@ class OStatusPlugin extends Plugin
         }
     }
 
+    /**
+     * Tell the FeedSub infrastructure whether we have any active OStatus
+     * usage for the feed; if not it'll be able to garbage-collect the
+     * feed subscription.
+     * 
+     * @param FeedSub $feedsub
+     * @param integer $count in/out
+     * @return mixed hook return code
+     */
+    function onFeedSubSubscriberCount($feedsub, &$count)
+    {
+        $oprofile = Ostatus_profile::staticGet('feeduri', $feedsub->uri);
+        if ($oprofile) {
+            $count += $oprofile->subscriberCount();
+        }
+        return true;
+    }
+
     /**
      * When about to subscribe to a remote user, start a server-to-server
      * PuSH subscription if needed. If we can't establish that, abort.