AA-159: Improving performance of get_course_assignments

We saw an increase in response time with recent changes to the logic
behind get_course_assignments. This effort works to better access
the information we need in order to improve performance.
Namely, this is done by using the course_blocks_api

lms/djangoapps/course_api/blocks/transformers/block_completion.py

@@ -16,6 +16,8 @@ class BlockCompletionTransformer(BlockStructureTransformer):
     READ_VERSION = 1
     WRITE_VERSION = 1
     COMPLETION = 'completion'
+    COMPLETE = 'complete'
+    RESUME_BLOCK = 'resume_block'
 
     @classmethod
     def name(cls):
@@ -43,9 +45,46 @@ class BlockCompletionTransformer(BlockStructureTransformer):
     def collect(cls, block_structure):
         block_structure.request_xblock_fields('completion_mode')
 
+    def mark_complete(self, course_block_completions, latest_completion_block_key, block_key, block_structure):
+        """
+        Helper function to mark a block as 'complete' as dictated by
+        course_block_completions (for problems) or all of a block's children being complete.
+        This also sets the 'resume_block' field as that is connected to the latest completed block.
+
+        :param course_block_completions: dict[course_completion_object] =  completion_value
+        :param latest_completion_block_key: block key for the latest completed block.
+        :param block_key: A opaque_keys.edx.locator.BlockUsageLocator object
+        :param block_structure: A BlockStructureBlockData object
+        """
+        if block_key in course_block_completions:
+            block_structure.override_xblock_field(block_key, self.COMPLETE, True)
+            if block_key == latest_completion_block_key:
+                block_structure.override_xblock_field(block_key, self.RESUME_BLOCK, True)
+
+        children = block_structure.get_children(block_key)
+        non_discussion_children = (child_key for child_key in children
+                                   if block_structure.get_xblock_field(child_key, 'category') != 'discussion')
+        child_complete = (block_structure.get_xblock_field(child_key, self.COMPLETE)
+                          for child_key in non_discussion_children)
+        if children and all(child_complete):
+            block_structure.override_xblock_field(block_key, self.COMPLETE, True)
+
+        if any(block_structure.get_xblock_field(child_key, self.RESUME_BLOCK) for child_key in children):
+            block_structure.override_xblock_field(block_key, self.RESUME_BLOCK, True)
+
     def transform(self, usage_info, block_structure):
         """
-        Mutates block_structure adding extra field which contains block's completion.
+        Mutates block_structure adding three extra fields which contains block's completion,
+        complete status, and if the block is a resume_block, indicating it is the most recently
+        completed block.
+
+        IMPORTANT!: There is a subtle, but important difference between 'completion' and 'complete'
+        which are both set in this transformer:
+        'completion': Returns a percentile (0.0 - 1.0) of correctness for a _problem_. This field will
+            be None for all other blocks that are not leaves and captured in BlockCompletion.
+        'complete': Returns a boolean indicating whether the block is complete. For problems, this will
+            be taken from a BlockCompletion entry existing. For all other blocks, it will be marked True
+            if all of the children of the block are all marked complete (this is calculated recursively)
         """
         def _is_block_an_aggregator_or_excluded(block_key):
             """
@@ -82,3 +121,9 @@ class BlockCompletionTransformer(BlockStructureTransformer):
             block_structure.set_transformer_block_field(
                 block_key, self, self.COMPLETION, completion_value
             )
+
+        latest_completion = completions.latest() if completions.exists() else None
+        if latest_completion:
+            latest_completion_block_key = latest_completion[0]
+            for block_key in block_structure.post_order_traversal():
+                self.mark_complete(completions_dict, latest_completion_block_key, block_key, block_structure)

lms/djangoapps/course_blocks/api.py

@@ -7,6 +7,7 @@ get_course_blocks function.
 from django.conf import settings
 from edx_when import field_data
 
+from lms.djangoapps.course_api.blocks.transformers.block_completion import BlockCompletionTransformer
 from openedx.core.djangoapps.content.block_structure.api import get_block_structure_manager
 from openedx.core.djangoapps.content.block_structure.transformers import BlockStructureTransformers
 from openedx.features.content_type_gating.block_transformers import ContentTypeGateTransformer
@@ -58,6 +59,7 @@ def get_course_blocks(
         transformers=None,
         collected_block_structure=None,
         allow_start_dates_in_future=False,
+        include_completion=False,
 ):
     """
     A higher order function implemented on top of the
@@ -91,6 +93,8 @@ def get_course_blocks(
     """
     if not transformers:
         transformers = BlockStructureTransformers(get_course_block_access_transformers(user))
+    if include_completion:
+        transformers += [BlockCompletionTransformer()]
     transformers.usage_info = CourseUsageInfo(starting_block_usage_key.course_key, user, allow_start_dates_in_future)
 
     return get_block_structure_manager(starting_block_usage_key.course_key).get_transformed(

lms/djangoapps/courseware/courses.py

@@ -52,13 +52,13 @@ from lms.djangoapps.courseware.access_utils import (
 )
 from lms.djangoapps.courseware.courseware_access_exception import CoursewareAccessException
 from lms.djangoapps.courseware.exceptions import CourseAccessRedirect
+from lms.djangoapps.course_blocks.api import get_course_blocks
 from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
 from openedx.core.djangoapps.enrollments.api import get_course_enrollment_details
 from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers
 from openedx.core.lib.api.view_utils import LazySequence
 from openedx.features.course_duration_limits.access import AuditExpiredError
 from openedx.features.course_experience import RELATIVE_DATES_FLAG
-from openedx.features.course_experience.utils import get_course_outline_block_tree
 from static_replace import replace_static_urls
 from student.models import CourseEnrollment
 from survey.utils import SurveyRequiredAccessError, check_survey_required_and_unanswered
@@ -517,31 +517,34 @@ def get_course_assignments(course_key, user, request, include_access=False):
 
     Each returned object is a namedtuple with fields: title, url, date, contains_gated_content, complete, past_due
     """
-    assignments = []
-    # Ideally this function is always called with a request being passed in, but because it is also
-    # a subfunction of `get_course_date_blocks` which does not require a request, we are being defensive here.
-    if not request:
-        return assignments
+    store = modulestore()
+    course_usage_key = store.make_course_usage_key(course_key)
+    block_data = get_course_blocks(user, course_usage_key, allow_start_dates_in_future=True, include_completion=True)
 
     now = datetime.now(pytz.UTC)
-    course_root_block = get_course_outline_block_tree(request, str(course_key), user, allow_start_dates_in_future=True)
-    for section in course_root_block.get('children', []):
-        for subsection in section.get('children', []):
-            if not subsection.get('due') or not subsection.get('graded'):
+    assignments = []
+    for section_key in block_data.get_children(course_usage_key):
+        for subsection_key in block_data.get_children(section_key):
+            due = block_data.get_xblock_field(subsection_key, 'due')
+            graded = block_data.get_xblock_field(subsection_key, 'graded', False)
+            if not due or not graded:
                 continue
 
-            contains_gated_content = include_access and subsection.get('contains_gated_content', False)
-            title = subsection.get('display_name', _('Assignment'))
+            contains_gated_content = include_access and block_data.get_xblock_field(
+                subsection_key, 'contains_gated_content', False)
+            title = block_data.get_xblock_field(subsection_key, 'display_name', _('Assignment'))
 
             url = None
-            assignment_released = not subsection.get('start') or subsection.get('start') < now
+            start = block_data.get_xblock_field(subsection_key, 'start')
+            assignment_released = not start or start < now
             if assignment_released:
-                url = subsection.get('lms_web_url')
+                url = reverse('jump_to', args=[course_key, subsection_key])
+                url = request and request.build_absolute_uri(url)
 
-            complete = subsection.get('complete')
-            past_due = not complete and subsection.get('due', now + timedelta(1)) < now
+            complete = block_data.get_xblock_field(subsection_key, 'complete', False)
+            past_due = not complete and due < now
             assignments.append(_Assignment(
-                subsection.get('id'), title, url, subsection.get('due'), contains_gated_content, complete, past_due
+                subsection_key, title, url, due, contains_gated_content, complete, past_due
             ))
 
     return assignments