Added careful caching to getRolesInContext, which is an expensive op

that requires climbing the entire aq chain on every call (and it gets
called a *lot*). A little investigation revealed that it is called
over and over for the same objects during a request for complex pages,
so a cache was added that can cut the work down to about 10% of its
current level.

lib/python/AccessControl/User.py

@@ -84,7 +84,7 @@
 ##############################################################################
 """Access control package"""
 
-__version__='$Revision: 1.88 $'[11:-2]
+__version__='$Revision: 1.89 $'[11:-2]
 
 import Globals, App.Undo, socket, regex
 from Globals import HTMLFile, MessageDialog, Persistent, PersistentMapping
@@ -131,6 +131,15 @@ class BasicUser(Implicit):
            including local roles assigned in context of
            the passed in object."""
         name=self.getUserName()
+        robj=self.REQUEST
+
+        # in-line caching
+        key='%s_%s' % (name, id(object))
+        rc=getattr(robj, '_rc__', {})
+        roles=rc.get(key, None)
+        if roles is not None:
+            return roles
+
         roles=self.getRoles()
         local={}
         while 1:
@@ -145,8 +154,13 @@ class BasicUser(Implicit):
                 object=object.im_self
                 continue
             break
-        joined=rolejoin(roles, local.keys())
-        return joined
+        roles=list(roles) + local.keys()
+
+        # in-line caching
+        if not hasattr(robj, '_rc__'):
+            robj._rc__={}
+        robj._rc__[key]=roles
+        return roles
 
 
     def getDomains(self):