(fix) cache sogo_folder_info records and avoid phantom subscriptions (fixes #4010)

SoObjects/SOGo/SOGoGCSFolder.m

@@ -424,7 +424,23 @@ static NSArray *childRecordFields = nil;
 
 - (GCSFolder *) ocsFolderForPath: (NSString *) _path
 {
-  return [[self folderManager] folderAtPath: _path];
+  NSDictionary *record;
+  SOGoCache *cache;
+
+  cache = [SOGoCache sharedCache];
+  record = [[cache valueForKey: _path] objectFromJSONString];
+
+  if (!record)
+    {
+      record = [[self folderManager] recordAtPath: _path];
+
+      if (!record)
+	return nil;
+
+      [cache setValue: [record jsonRepresentation]  forKey: _path];
+    }
+
+  return [[self folderManager] folderForRecord: record];
 }
 
 - (BOOL) folderIsMandatory
@@ -578,6 +594,7 @@ static NSArray *childRecordFields = nil;
       [self removeFolderSettings: moduleSettings
                    withReference: [self folderReference]];
       [us synchronize];
+      [[SOGoCache sharedCache] removeValueForKey: ocsPath];
 
       if ([[context request] handledByDefaultHandler])
         [self sendFolderAdvisoryTemplate: @"Removal"];

SoObjects/SOGo/SOGoParentFolder.m

@@ -291,14 +291,8 @@ static SoSecurityManager *sm = nil;
   // This is important because user A could delete folder X, and user B has subscribed to it.
   // If the "default roles" are enabled for calendars/address books, -validatePersmission:.. will
   // work (grabbing the default role) and the deleted resource will be incorrectly returned.
-  //
-  // FIXME - 2015/01/29 - this fix (24c6c8c91d421594bd51f07904d4cd3911cd187c) was reverted. Normally, we should add
-  // [subscribedFolder ocsFolderForPath: [subscribedFolder ocsPath]] to check the existence of the folder but it causes
-  // massive SQL traffic.
-  // 
-  // The proper fix would be to check upon login and only upon login if GCS folders that we're subscribed to are still existent.
-  //
   if (subscribedFolder
+      && [subscribedFolder ocsFolderForPath: [subscribedFolder ocsPath]]
       && ![sm validatePermission: SOGoPerm_AccessObject
 			onObject: subscribedFolder
 		       inContext: context])