👌 IMPROVE: Move default user caching to StorageBackend

Currently it is cached on the `UserCollection`,
but this means that, on profile switching,
it would return a user associated with the wrong backend instance.

aiida/orm/implementation/storage_backend.py

@@ -25,6 +25,7 @@
         BackendQueryBuilder,
         BackendUserCollection,
     )
+    from aiida.orm.users import User
     from aiida.repository.backend.abstract import AbstractRepositoryBackend
 
 __all__ = ('StorageBackend',)
@@ -84,6 +85,7 @@ def __init__(self, profile: 'Profile') -> None:
         """
         from aiida.orm.autogroup import AutogroupManager
         self._profile = profile
+        self._default_user: Optional['User'] = None
         self._autogroup = AutogroupManager(self)
 
     @abc.abstractmethod
@@ -161,6 +163,21 @@ def nodes(self) -> 'BackendNodeCollection':
     def users(self) -> 'BackendUserCollection':
         """Return the collection of users"""
 
+    @property
+    def default_user(self) -> Optional['User']:
+        """Return the default user for the profile, if it has been created.
+
+        This is cached, since it is a frequently used operation, for creating other entities.
+        """
+        from aiida.orm import QueryBuilder, User
+
+        if self._default_user is None and self.profile.default_user_email:
+            query = QueryBuilder().append(User, filters={'email': self.profile.default_user_email})
+            results = query.all(flat=True)
+            if results:
+                self._default_user = results[0]
+        return self._default_user
+
     @abc.abstractmethod
     def query(self) -> 'BackendQueryBuilder':
         """Return an instance of a query builder implementation for this backend"""

aiida/orm/users.py

@@ -31,7 +31,6 @@ def _entity_base_cls() -> Type['User']:
 
     def __init__(self, entity_class: Type['User'], backend: Optional['StorageBackend'] = None) -> None:
         super().__init__(entity_class=entity_class, backend=backend)
-        self._default_user: Optional[User] = None
 
     def get_or_create(self, email: str, **kwargs) -> Tuple[bool, 'User']:
         """Get the existing user with a given email address or create an unstored one
@@ -48,23 +47,7 @@ def get_or_create(self, email: str, **kwargs) -> Tuple[bool, 'User']:
 
     def get_default(self) -> Optional['User']:
         """Get the current default user"""
-        if self._default_user is None:
-            email = self.backend.profile.default_user_email
-            if not email:
-                self._default_user = None
-
-            try:
-                self._default_user = self.get(email=email)
-            except (exceptions.MultipleObjectsError, exceptions.NotExistent):
-                self._default_user = None
-
-        return self._default_user
-
-    def reset(self) -> None:
-        """
-        Reset internal caches (default user).
-        """
-        self._default_user = None
+        return self.backend.default_user
 
 
 class User(entities.Entity['BackendUser']):

aiida/storage/psql_dos/backend.py

@@ -19,7 +19,6 @@
 
 from aiida.common.exceptions import ClosedStorage, IntegrityError
 from aiida.manage.configuration.profile import Profile
-from aiida.orm import User
 from aiida.orm.entities import EntityTypes
 from aiida.orm.implementation import BackendEntity, StorageBackend
 from aiida.storage.log import STORAGE_LOGGER
@@ -113,8 +112,6 @@ def get_session(self) -> Session:
     def close(self) -> None:
         if self._session_factory is None:
             return  # the instance is already closed, and so this is a no-op
-        # reset the cached default user instance, since it will now have no associated session
-        User.collection(self).reset()
         # close the connection
         # pylint: disable=no-member
         engine = self._session_factory.bind
@@ -137,15 +134,13 @@ def _clear(self, recreate_user: bool = True) -> None:
 
             # save the default user
             default_user_kwargs = None
-            if recreate_user:
-                default_user = User.collection(self).get_default()
-                if default_user is not None:
-                    default_user_kwargs = {
-                        'email': default_user.email,
-                        'first_name': default_user.first_name,
-                        'last_name': default_user.last_name,
-                        'institution': default_user.institution,
-                    }
+            if recreate_user and self.default_user is not None:
+                default_user_kwargs = {
+                    'email': self.default_user.email,
+                    'first_name': self.default_user.first_name,
+                    'last_name': self.default_user.last_name,
+                    'institution': self.default_user.institution,
+                }
 
             # now clear the database
             for table_name in (
@@ -158,8 +153,6 @@ def _clear(self, recreate_user: bool = True) -> None:
             # restore the default user
             if recreate_user and default_user_kwargs:
                 session.add(DbUser(**default_user_kwargs))
-            # clear aiida's cache of the default user
-            User.collection(self).reset()
 
         # Clear the repository and reset the repository UUID
         container = Container(self.profile.repository_path / 'container')