Rework refresh_vgrid_map in order to init all vgrid entries in VGRIDS early

and to never skip init of the individual fields in those vgrid dicts, even if
the source file for the corresponding field (like `owners` or `members`) is
older than the map timestamp of the current vgrid map file. That should address
a potential race when vgrids are modified during long-running refresh calls and
any other causes for those fields missing in the existing map.

Remove an unused leftover variable in check_vgrid_access.

Author: jonasbardino

mig/shared/vgridaccess.py

@@ -401,18 +401,18 @@ def refresh_vgrid_map(configuration, clean=False):
     optional_conf = [SETTINGS, ]
 
     for vgrid in all_vgrids:
+        # Make sure vgrid dict exists before filling it
+        vgrid_map[VGRIDS][vgrid] = vgrid_map[VGRIDS].get(vgrid, {})
         for (field, name, list_call) in conf_read:
             conf_path = os.path.join(configuration.vgrid_home, vgrid, name)
             if not os.path.isfile(conf_path):
-                # Make sure vgrid dict exists before filling it
-                vgrid_map[VGRIDS][vgrid] = vgrid_map[VGRIDS].get(vgrid, {})
                 vgrid_map[VGRIDS][vgrid][field] = []
                 if vgrid != default_vgrid and field not in optional_conf:
                     _logger.warning('missing file: %s' %
                                     conf_path)
                     dirty[VGRIDS] = dirty.get(VGRIDS, []) + [vgrid]
 
-            elif vgrid not in vgrid_map[VGRIDS] or \
+            elif field not in vgrid_map[VGRIDS][vgrid] or \
                     os.path.getmtime(conf_path) >= map_stamp:
                 (status, entries) = list_call(vgrid, configuration,
                                               recursive=False)
@@ -425,6 +425,8 @@ def refresh_vgrid_map(configuration, clean=False):
                 vgrid_map[VGRIDS][vgrid] = map_entry
                 vgrid_map[VGRIDS][vgrid][field] = entries
                 dirty[VGRIDS] = dirty.get(VGRIDS, []) + [vgrid]
+            else:
+                _logger.debug("caching %s for %s in vgrid map" % (name, vgrid))
     # Remove any missing vgrids from map
     missing_vgrids = [vgrid for vgrid in vgrid_map[VGRIDS]
                       if not vgrid in all_vgrids]
@@ -853,7 +855,6 @@ def check_vgrid_access(configuration, client_id, vgrid_name, recursive=True,
     the vgrid module and should replace that one everywhere that only vgrid map
     (cached) lookups are needed.
     """
-    vgrid_access = [default_vgrid]
     vgrid_map = get_vgrid_map(configuration, recursive, caching)
     vgrid_entry = vgrid_map.get(VGRIDS, {}).get(
         vgrid_name, {OWNERS: [], MEMBERS: []})