perf: Reduce queries by passing grading policy has through when it

exists

Author: Tycho Hob

lms/djangoapps/grades/models.py

@@ -461,7 +461,7 @@ def bulk_read_grades(cls, user_id, course_key):
             )
 
     @classmethod
-    def update_or_create_grade(cls, **params):
+    def update_or_create_grade(cls, grading_policy_hash=None, **params):
         """
         Wrapper for objects.update_or_create.
         """
@@ -490,11 +490,11 @@ def update_or_create_grade(cls, **params):
             grade.save()
 
         cls._emit_grade_calculated_event(grade)
-        cls._emit_openedx_persistent_subsection_grade_changed_event(grade, visible_blocks)
+        cls._emit_openedx_persistent_subsection_grade_changed_event(grade, visible_blocks, grading_policy_hash)
         return grade
 
     @classmethod
-    def bulk_create_grades(cls, grade_params_iter, user_id, course_key):
+    def bulk_create_grades(cls, grade_params_iter, user_id, course_key, grading_policy_hash=None):
         """
         Bulk creation of grades.
         """
@@ -514,7 +514,7 @@ def bulk_create_grades(cls, grade_params_iter, user_id, course_key):
         grades = cls.objects.bulk_create(grades)
         for grade, visible_blocks in zip(grades, visible_blocks_list, strict=True):
             cls._emit_grade_calculated_event(grade)
-            cls._emit_openedx_persistent_subsection_grade_changed_event(grade, visible_blocks)
+            cls._emit_openedx_persistent_subsection_grade_changed_event(grade, visible_blocks, grading_policy_hash)
         return grades
 
     @classmethod
@@ -545,21 +545,26 @@ def _emit_grade_calculated_event(grade):
         events.subsection_grade_calculated(grade)
 
     @staticmethod
-    def _emit_openedx_persistent_subsection_grade_changed_event(grade, visible_blocks):
+    def _emit_openedx_persistent_subsection_grade_changed_event(grade, visible_blocks, grading_policy_hash=None):
         """
         When called emits an event when a persistent subsection grade is created or updated.
+
+        ``grading_policy_hash`` should be supplied by callers that already have the course's
+        block structure loaded, so it can be reused instead of loading the course from the
+        modulestore (an extra query per event).  When not provided, it is computed here.
         """
         # .. event_implemented_name: PERSISTENT_SUBSECTION_GRADE_CHANGED
         # .. event_type: org.openedx.learning.course.persistent_subsection_grade.changed.v1
-        try:
-            grading_policy_hash = GradesCourseData(user=None, course_key=grade.course_id).grading_policy_hash
-        except Exception:  # pylint: disable=broad-except
-            grading_policy_hash = ""
-            log.debug(
-                "Unable to compute grading_policy_hash for course %s",
-                grade.course_id,
-                exc_info=True,
-            )
+        if grading_policy_hash is None:
+            try:
+                grading_policy_hash = GradesCourseData(user=None, course_key=grade.course_id).grading_policy_hash
+            except Exception:  # pylint: disable=broad-except
+                grading_policy_hash = ""
+                log.debug(
+                    "Unable to compute grading_policy_hash for course %s",
+                    grade.course_id,
+                    exc_info=True,
+                )
 
         xblocks_scoring_data = [
             XBlockWithScoringData(

lms/djangoapps/grades/subsection_grade.py

@@ -281,12 +281,17 @@ def __init__(self, subsection, course_structure, submissions_scores, csm_scores)
 
         super().__init__(subsection, all_total, graded_total)
 
-    def update_or_create_model(self, student, score_deleted=False, force_update_subsections=False):
+    def update_or_create_model(
+        self, student, score_deleted=False, force_update_subsections=False, grading_policy_hash=None
+    ):
         """
         Saves or updates the subsection grade in a persisted model.
         """
         if self._should_persist_per_attempted(score_deleted, force_update_subsections):
-            model = PersistentSubsectionGrade.update_or_create_grade(**self._persisted_model_params(student))
+            model = PersistentSubsectionGrade.update_or_create_grade(
+                grading_policy_hash=grading_policy_hash,
+                **self._persisted_model_params(student),
+            )
 
             if hasattr(model, 'override'):
                 # When we're doing an update operation, the PersistentSubsectionGrade model
@@ -299,7 +304,7 @@ def update_or_create_model(self, student, score_deleted=False, force_update_subs
             return model
 
     @classmethod
-    def bulk_create_models(cls, student, subsection_grades, course_key):
+    def bulk_create_models(cls, student, subsection_grades, course_key, grading_policy_hash=None):
         """
         Saves the subsection grade in a persisted model.
         """
@@ -309,7 +314,9 @@ def bulk_create_models(cls, student, subsection_grades, course_key):
             if subsection_grade
             if subsection_grade._should_persist_per_attempted()  # pylint: disable=protected-access
         ]
-        return PersistentSubsectionGrade.bulk_create_grades(params, student.id, course_key)
+        return PersistentSubsectionGrade.bulk_create_grades(
+            params, student.id, course_key, grading_policy_hash=grading_policy_hash
+        )
 
     def _should_persist_per_attempted(self, score_deleted=False, force_update_subsections=False):
         """

lms/djangoapps/grades/subsection_grade_factory.py

@@ -57,7 +57,10 @@ def create(self, subsection, read_only=False, force_calculate=False):
                 if read_only:
                     self._unsaved_subsection_grades[subsection_grade.location] = subsection_grade
                 else:
-                    grade_model = subsection_grade.update_or_create_model(self.student)
+                    grade_model = subsection_grade.update_or_create_model(
+                        self.student,
+                        grading_policy_hash=self.course_data.grading_policy_hash,
+                    )
                     self._update_saved_subsection_grade(subsection.location, grade_model)
         return subsection_grade
 
@@ -66,7 +69,8 @@ def bulk_create_unsaved(self):
         Bulk creates all the unsaved subsection_grades to this point.
         """
         CreateSubsectionGrade.bulk_create_models(
-            self.student, list(self._unsaved_subsection_grades.values()), self.course_data.course_key
+            self.student, list(self._unsaved_subsection_grades.values()), self.course_data.course_key,
+            grading_policy_hash=self.course_data.grading_policy_hash,
         )
         self._unsaved_subsection_grades.clear()
 
@@ -100,7 +104,8 @@ def update(self, subsection, only_if_higher=None, score_deleted=False, force_upd
             grade_model = calculated_grade.update_or_create_model(
                 self.student,
                 score_deleted,
-                force_update_subsections
+                force_update_subsections,
+                grading_policy_hash=self.course_data.grading_policy_hash,
             )
             self._update_saved_subsection_grade(subsection.location, grade_model)