Handle the roster order cache as a real cache

When an external (or internal) event may cause the order of the
cache to be modified, or new elements to be added, schedule it
for a rebuild. Otherwise, don’t, and only rebuild it when
refreshing (that should improve refresh speed a lot).

Also, if the position in the roster is further than the total size
of the roster, go back to the top instead of displaying an empty
window with “+++”.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/roster.py b/src/roster.py
index b0f3cf65..5ddbdbb2 100644
--- a/src/roster.py
+++ b/src/roster.py
@@ -17,6 +17,7 @@ from contact import Contact
 from roster_sorting import SORTING_METHODS, GROUP_SORTING_METHODS
 
 from os import path as p
+from datetime import datetime
 from common import safeJID
 from sleekxmpp import JID
 from sleekxmpp.exceptions import IqError, IqTimeout
@@ -43,6 +44,17 @@ class Roster(object):
         self.groups = {}
         self.contacts = {}
 
+        # Used for caching roster infos
+        self.last_built = datetime.now()
+        self.last_modified = datetime.now()
+
+    def modified(self):
+        self.last_modified = datetime.now()
+
+    @property
+    def needs_rebuild(self):
+        return self.last_modified >= self.last_built
+
     def __getitem__(self, key):
         """Get a Contact from his bare JID"""
         key = safeJID(key).bare