Prevent excess loading from the roster db.

Fixes issue #148

2 files changed, 12 insertions, 7 deletions

diff --git a/sleekxmpp/roster/multi.py b/sleekxmpp/roster/multi.py
index 28876814..84577a9d 100644
--- a/sleekxmpp/roster/multi.py
+++ b/sleekxmpp/roster/multi.py
@@ -9,7 +9,6 @@
 from sleekxmpp.xmlstream import JID
 from sleekxmpp.roster import RosterNode
 
-
 class Roster(object):
 
     """
@@ -104,10 +103,13 @@ class Roster(object):
             db -- The new datastore interface.
         """
         self.db = db
-        for node in self.db.entries(None, {}):
-            self.add(node)
-        for node in self._rosters:
+        existing_entries = set(self._rosters)
+        new_entries = set(self.db.entries(None, {}))
+
+        for node in existing_entries:
             self._rosters[node].set_backend(db)
+        for node in new_entries - existing_entries:
+            self.add(node)
 
     def reset(self):
         """
diff --git a/sleekxmpp/roster/single.py b/sleekxmpp/roster/single.py
index 633f23f6..611f8944 100644
--- a/sleekxmpp/roster/single.py
+++ b/sleekxmpp/roster/single.py
@@ -109,10 +109,13 @@ class RosterNode(object):
             db -- The new datastore interface.
         """
         self.db = db
-        for jid in self.db.entries(self.jid):
-            self.add(jid)
-        for jid in self._jids:
+        existing_entries = set(self._jids)
+        new_entries = set(self.db.entries(self.jid, {}))
+        
+        for jid in existing_entries:
             self._jids[jid].set_backend(db)
+        for jid in new_entries - existing_entries:
+            self.add(jid)
 
     def add(self, jid, name='', groups=None, afrom=False, ato=False,
             pending_in=False, pending_out=False, whitelisted=False,