Improve performance on trust deletion

During a trust deletion, the backend will fetch all trust by the same
trustor and look for redelegations to be deleted as well. If you have
a considerable amount of trusts that call becomes expensive. Just by
pushing this filter into the backend, the response time for the api call
just depends on the number of redelegations for that trust.

Change-Id: Id3a820fca0bb20561ba031797d2b0fb96ba1f78d
Closes-Bug: #1935840

keystone/trust/backends/base.py

@@ -48,7 +48,7 @@ class TrustDriverBase(object, metaclass=abc.ABCMeta):
         raise exception.NotImplemented()  # pragma: no cover
 
     @abc.abstractmethod
-    def list_trusts_for_trustor(self, trustor):
+    def list_trusts_for_trustor(self, trustor, redelegated_trust_id=None):
         raise exception.NotImplemented()  # pragma: no cover
 
     @abc.abstractmethod

keystone/trust/backends/sql.py

@@ -171,11 +171,15 @@ class Trust(base.TrustDriverBase):
                       filter_by(trustee_user_id=trustee_user_id))
             return [trust_ref.to_dict() for trust_ref in trusts]
 
-    def list_trusts_for_trustor(self, trustor_user_id):
+    def list_trusts_for_trustor(self, trustor_user_id,
+                                redelegated_trust_id=None):
         with sql.session_for_read() as session:
             trusts = (session.query(TrustModel).
                       filter_by(deleted_at=None).
                       filter_by(trustor_user_id=trustor_user_id))
+            if redelegated_trust_id:
+                trusts = trusts.filter_by(
+                    redelegated_trust_id=redelegated_trust_id)
             return [trust_ref.to_dict() for trust_ref in trusts]
 
     @sql.handle_conflicts(conflict_type='trust')

keystone/trust/core.py

@@ -194,17 +194,17 @@ class Manager(manager.Manager):
         """
         trust = self.driver.get_trust(trust_id)
         trusts = self.driver.list_trusts_for_trustor(
-            trust['trustor_user_id'])
+            trust['trustor_user_id'],
+            redelegated_trust_id=trust_id)
 
         for t in trusts:
-            if t.get('redelegated_trust_id') == trust_id:
-                # recursive call to make sure all notifications are sent
-                try:
-                    self.delete_trust(t['id'])
-                except exception.TrustNotFound:  # nosec
-                    # if trust was deleted by concurrent process
-                    # consistency must not suffer
-                    pass
+            # recursive call to make sure all notifications are sent
+            try:
+                self.delete_trust(t['id'])
+            except exception.TrustNotFound:  # nosec
+                # if trust was deleted by concurrent process
+                # consistency must not suffer
+                pass
 
         # end recursion
         self.driver.delete_trust(trust_id)