From 8b4b5a4547937982edb00462b338fcfe9089f2d3 Mon Sep 17 00:00:00 2001
From: Calen Pennington <cale@edx.org>
Date: Mon, 1 Jul 2019 13:19:23 -0400
Subject: [PATCH] Move stable_bucketing into its own library to minimize
 circular dependencies

---
 .../experiments/stable_bucketing.py           | 27 +++++++++++++++++++
 lms/djangoapps/experiments/utils.py           | 25 +++--------------
 .../course_duration_limits/resolvers.py       |  2 +-
 openedx/features/discounts/applicability.py   |  2 ++
 4 files changed, 33 insertions(+), 23 deletions(-)
 create mode 100644 lms/djangoapps/experiments/stable_bucketing.py

diff --git a/lms/djangoapps/experiments/stable_bucketing.py b/lms/djangoapps/experiments/stable_bucketing.py
new file mode 100644
index 0000000000..0bc903ee8b
--- /dev/null
+++ b/lms/djangoapps/experiments/stable_bucketing.py
@@ -0,0 +1,27 @@
+"""
+An implementation of a stable bucketing algorithm that can be used
+to reliably group users into experiments.
+"""
+
+import hashlib
+import re
+
+
+def stable_bucketing_hash_group(group_name, group_count, username):
+    """
+    Return the bucket that a user should be in for a given stable bucketing assignment.
+
+    This function has been verified to return the same values as the stable bucketing
+    functions in javascript and the master experiments table.
+
+    Arguments:
+        group_name: The name of the grouping/experiment.
+        group_count: How many groups to bucket users into.
+        username: The username of the user being bucketed.
+    """
+    hasher = hashlib.md5()
+    hasher.update(group_name.encode('utf-8'))
+    hasher.update(username.encode('utf-8'))
+    hash_str = hasher.hexdigest()
+
+    return int(re.sub('[8-9a-f]', '1', re.sub('[0-7]', '0', hash_str)), 2) % group_count
diff --git a/lms/djangoapps/experiments/utils.py b/lms/djangoapps/experiments/utils.py
index e921ac7392..3c00f6984c 100644
--- a/lms/djangoapps/experiments/utils.py
+++ b/lms/djangoapps/experiments/utils.py
@@ -4,9 +4,7 @@ Utilities to facilitate experimentation
 
 from __future__ import absolute_import
 
-import hashlib
 import logging
-import re
 from decimal import Decimal
 
 import six
@@ -27,6 +25,9 @@ from openedx.features.course_duration_limits.models import CourseDurationLimitCo
 from student.models import CourseEnrollment
 from xmodule.partitions.partitions_service import get_all_partitions_for_course, get_user_partition_groups
 
+# Import this for backwards compatibility (so that anyone importing this function from here doesn't break)
+from .stable_bucketing import stable_bucketing_hash_group  # pylint: disable=unused-import
+
 logger = logging.getLogger(__name__)
 
 
@@ -386,23 +387,3 @@ def get_program_context(course, user_enrollments):
             }
     return program_key
 # TODO: clean up as part of REVEM-199 (START)
-
-
-def stable_bucketing_hash_group(group_name, group_count, username):
-    """
-    Return the bucket that a user should be in for a given stable bucketing assignment.
-
-    This function has been verified to return the same values as the stable bucketing
-    functions in javascript and the master experiments table.
-
-    Arguments:
-        group_name: The name of the grouping/experiment.
-        group_count: How many groups to bucket users into.
-        username: The username of the user being bucketed.
-    """
-    hasher = hashlib.md5()
-    hasher.update(group_name.encode('utf-8'))
-    hasher.update(username.encode('utf-8'))
-    hash_str = hasher.hexdigest()
-
-    return int(re.sub('[8-9a-f]', '1', re.sub('[0-7]', '0', hash_str)), 2) % group_count
diff --git a/openedx/features/course_duration_limits/resolvers.py b/openedx/features/course_duration_limits/resolvers.py
index 31c627cac3..d22a36b83e 100644
--- a/openedx/features/course_duration_limits/resolvers.py
+++ b/openedx/features/course_duration_limits/resolvers.py
@@ -15,7 +15,7 @@ from eventtracking import tracker
 
 from course_modes.models import CourseMode
 from courseware.date_summary import verified_upgrade_deadline_link
-from lms.djangoapps.experiments.utils import stable_bucketing_hash_group
+from lms.djangoapps.experiments.stable_bucketing import stable_bucketing_hash_group
 from openedx.core.djangoapps.catalog.utils import get_course_run_details
 from openedx.core.djangoapps.schedules.resolvers import (
     BinnedSchedulesBaseResolver,
diff --git a/openedx/features/discounts/applicability.py b/openedx/features/discounts/applicability.py
index 0c2bb26ea1..9caeb664bd 100644
--- a/openedx/features/discounts/applicability.py
+++ b/openedx/features/discounts/applicability.py
@@ -8,8 +8,10 @@ Keep in mind that the code in this file only applies to discounts controlled in
 not other discounts like coupons or enterprise/program offers configured in ecommerce.
 
 """
+import crum
 from course_modes.models import CourseMode
 from entitlements.models import CourseEntitlement
+from lms.djangoapps.experiments.stable_bucketing import stable_bucketing_hash_group
 from openedx.core.djangoapps.waffle_utils import WaffleFlag, WaffleFlagNamespace
 from openedx.features.discounts.models import DiscountRestrictionConfig
 from student.models import CourseEnrollment