"""
This module contains tasks for asynchronous execution of grade updates.
"""
from celery import task
from django.conf import settings
from django.contrib.auth.models import User
from django.core.exceptions import ValidationError
from django.db.utils import DatabaseError
from logging import getLogger
log = getLogger(__name__)
try:
import newrelic.agent
except ImportError:
newrelic = None # pylint: disable=invalid-name
from celery_utils.logged_task import LoggedTask
from celery_utils.persist_on_failure import PersistOnFailureTask
from courseware.model_data import get_score
from lms.djangoapps.course_blocks.api import get_course_blocks
from lms.djangoapps.courseware import courses
from opaque_keys.edx.keys import CourseKey, UsageKey
from opaque_keys.edx.locator import CourseLocator
from student.models import CourseEnrollment
from submissions import api as sub_api
from track.event_transaction_utils import (
set_event_transaction_type,
set_event_transaction_id,
)
from util.date_utils import from_timestamp
from xmodule.modulestore.django import modulestore
from .constants import ScoreDatabaseTableEnum
from .new.subsection_grade import SubsectionGradeFactory
from .new.course_grade import CourseGradeFactory
from .signals.signals import SUBSECTION_SCORE_CHANGED
from .transformer import GradesTransformer
class DatabaseNotReadyError(IOError):
"""
Subclass of IOError to indicate the database has not yet committed
the data we're trying to find.
"""
pass
KNOWN_RETRY_ERRORS = ( # Errors we expect occasionally, should be resolved on retry
DatabaseError,
ValidationError,
DatabaseNotReadyError
)
RECALCULATE_GRADE_DELAY = 2 # in seconds, to prevent excessive _has_db_updated failures. See TNL-6424.
class _BaseTask(PersistOnFailureTask, LoggedTask): # pylint: disable=abstract-method
"""
Include persistence features, as well as logging of task invocation.
"""
abstract = True
@task(base=_BaseTask)
def compute_grades_for_course(course_key, offset, batch_size):
"""
Compute grades for a set of students in the specified course.
The set of students will be determined by the order of enrollment date, and
limited to at most <batch_size> students, starting from the specified
offset.
"""
course = courses.get_course_by_id(CourseKey.from_string(course_key))
enrollments = CourseEnrollment.objects.filter(course_id=course.id).order_by('created')
student_iter = (enrollment.user for enrollment in enrollments[offset:offset + batch_size])
list(CourseGradeFactory().iter(
course,
students=student_iter,
read_only=False,
))
@task(bind=True, base=_BaseTask, default_retry_delay=30, routing_key=settings.RECALCULATE_GRADES_ROUTING_KEY)
def recalculate_subsection_grade_v3(self, **kwargs):
"""
Latest version of the recalculate_subsection_grade task. See docstring
for _recalculate_subsection_grade for further description.
"""
_recalculate_subsection_grade(self, **kwargs)
def _recalculate_subsection_grade(self, **kwargs):
"""
Updates a saved subsection grade.
Keyword Arguments:
user_id (int): id of applicable User object
anonymous_user_id (int, OPTIONAL): Anonymous ID of the User
course_id (string): identifying the course
usage_id (string): identifying the course block
only_if_higher (boolean): indicating whether grades should
be updated only if the new raw_earned is higher than the
previous value.
expected_modified_time (serialized timestamp): indicates when the task
was queued so that we can verify the underlying data update.
score_deleted (boolean): indicating whether the grade change is
a result of the problem's score being deleted.
event_transaction_id (string): uuid identifying the current
event transaction.
event_transaction_type (string): human-readable type of the
event at the root of the current event transaction.
score_db_table (ScoreDatabaseTableEnum): database table that houses
the changed score. Used in conjunction with expected_modified_time.
"""
try:
course_key = CourseLocator.from_string(kwargs['course_id'])
scored_block_usage_key = UsageKey.from_string(kwargs['usage_id']).replace(course_key=course_key)
if newrelic:
newrelic.agent.add_custom_parameter('course_id', unicode(course_key))
newrelic.agent.add_custom_parameter('usage_id', unicode(scored_block_usage_key))
# The request cache is not maintained on celery workers,
# where this code runs. So we take the values from the
# main request cache and store them in the local request
# cache. This correlates model-level grading events with
# higher-level ones.
set_event_transaction_id(kwargs.get('event_transaction_id'))
set_event_transaction_type(kwargs.get('event_transaction_type'))
# Verify the database has been updated with the scores when the task was
# created. This race condition occurs if the transaction in the task
# creator's process hasn't committed before the task initiates in the worker
# process.
has_database_updated = _has_db_updated_with_new_score(self, scored_block_usage_key, **kwargs)
if not has_database_updated:
raise DatabaseNotReadyError
_update_subsection_grades(
course_key,
scored_block_usage_key,
kwargs['only_if_higher'],
kwargs['user_id'],
)
except Exception as exc: # pylint: disable=broad-except
if not isinstance(exc, KNOWN_RETRY_ERRORS):
log.info("tnl-6244 grades unexpected failure: {}. task id: {}. kwargs={}".format(
repr(exc),
self.request.id,
kwargs,
))
raise self.retry(kwargs=kwargs, exc=exc)
def _has_db_updated_with_new_score(self, scored_block_usage_key, **kwargs):
"""
Returns whether the database has been updated with the
expected new score values for the given problem and user.
"""
if kwargs['score_db_table'] == ScoreDatabaseTableEnum.courseware_student_module:
score = get_score(kwargs['user_id'], scored_block_usage_key)
found_modified_time = score.modified if score is not None else None
else:
assert kwargs['score_db_table'] == ScoreDatabaseTableEnum.submissions
score = sub_api.get_score(
{
"student_id": kwargs['anonymous_user_id'],
"course_id": unicode(scored_block_usage_key.course_key),
"item_id": unicode(scored_block_usage_key),
"item_type": scored_block_usage_key.block_type,
}
)
found_modified_time = score['created_at'] if score is not None else None
if score is None:
# score should be None only if it was deleted.
# Otherwise, it hasn't yet been saved.
db_is_updated = kwargs['score_deleted']
else:
db_is_updated = found_modified_time >= from_timestamp(kwargs['expected_modified_time'])
if not db_is_updated:
log.info(
u"Persistent Grades: tasks._has_database_updated_with_new_score is False. Task ID: {}. Kwargs: {}. Found "
u"modified time: {}".format(
self.request.id,
kwargs,
found_modified_time,
)
)
return db_is_updated
def _update_subsection_grades(
course_key,
scored_block_usage_key,
only_if_higher,
user_id,
):
"""
A helper function to update subsection grades in the database
for each subsection containing the given block, and to signal
that those subsection grades were updated.
"""
student = User.objects.get(id=user_id)
store = modulestore()
with store.bulk_operations(course_key):
course_structure = get_course_blocks(student, store.make_course_usage_key(course_key))
subsections_to_update = course_structure.get_transformer_block_field(
scored_block_usage_key,
GradesTransformer,
'subsections',
set(),
)
course = store.get_course(course_key, depth=0)
subsection_grade_factory = SubsectionGradeFactory(student, course, course_structure)
for subsection_usage_key in subsections_to_update:
if subsection_usage_key in course_structure:
subsection_grade = subsection_grade_factory.update(
course_structure[subsection_usage_key],
only_if_higher,
)
SUBSECTION_SCORE_CHANGED.send(
sender=None,
course=course,
course_structure=course_structure,
user=student,
subsection_grade=subsection_grade,
)