Minor cleanup from patch 429047

Fixes the nits from I3db0cf27d3cfdf6cf7c5bb34ec1b27ef80c139f4. No
major changes.

Change-Id: I801c1964d0ea99b3e6f69ff8f82f471b2ccdbef5

keystone/identity/backends/base.py

@@ -223,7 +223,7 @@ class IdentityDriverBase(object):
 
     @abc.abstractmethod
     def unset_default_project_id(self, project_id):
-        """Unset a users default project given a specific project ID.
+        """Unset a user's default project given a specific project ID.
 
         :param str project_id: project ID
 

keystone/identity/backends/ldap/core.py

@@ -88,8 +88,8 @@ class Identity(base.IdentityDriverBase):
         return self.user.get_all_filtered(hints)
 
     def unset_default_project_id(self, project_id):
-        # This function is not implemented for the LDAP backend
-        # LDAP backend is readonly.
+        # This function is not implemented for the LDAP backend. The LDAP
+        # backend is readonly.
         self._disallow_write()
 
     def get_user_by_name(self, user_name, domain_id):

keystone/identity/core.py

@@ -491,7 +491,7 @@ class Manager(manager.Manager):
         self.event_callbacks = {
             notifications.ACTIONS.deleted: {
                 'domain': [self._domain_deleted],
-                'project': [self._set_default_project_to_none],
+                'project': [self._unset_default_project],
             },
         }
 
@@ -522,15 +522,13 @@ class Manager(manager.Manager):
                            'cleanup.'),
                           {'userid': user['id'], 'domainid': domain_id})
 
-    def _set_default_project_to_none(self, service, resource_type, operation,
-                                     payload):
+    def _unset_default_project(self, service, resource_type, operation,
+                               payload):
         """Callback, clears user default_project_id after project deletion.
 
-        Notification approach was used instead of using a FK constraint.
-        Reason being, operators are allowed to have separate backends for
-        various keystone subsystems. This doesn't guarantee that projects and
-        users will be stored in the same backend, meaning we can't rely on FK
-        constraints to do this work for us.
+        Notifications are used to unset a user's default project because
+        there is no foreign key to the project. Projects can be in a non-SQL
+        backend, making FKs impossible.
 
         """
         project_id = payload['resource_info']

keystone/releasenotes/notes/unset-user-default_project_id-when-project-is-deleted-4d42c841b6e7e54e.yaml

@@ -1,14 +1,13 @@
 fixes:
   - |
     [`bug 1523369 <https://bugs.launchpad.net/keystone/+bug/1523369>`_]
-    Currently, if a project is deleted, it is not removed as a user's default
-    project id. Now the default project id is set to none, however changes may
-    not be visible until memcache end of life.
+    Deleting a project will now cause it to be removed as a default project
+    for users. If caching is enabled the changes may not be visible until the
+    user's cache entry expires.
 
 upgrade:
   - |
-    The identity backend driver interface has changed. We've added a new
-    ``unset_default_project_id(project_id)`` method to unset a users default
-    project id matching the given project id. If you have a custom
-    implementation for the identity driver, you will need to implement this
-    new method.
+    The identity backend driver interface has changed. A new method,
+    ``unset_default_project_id(project_id)``, was added to unset a user's
+    default project ID for a given project ID. Custom backend implementations
+    must implement this method.