refactor: create cache_utils.py, move stuff there

This will eventually support the creation of a `content_metadata`
module, and we'll yank stuff out of the `subsidy_access_policy` module
into this new module.

enterprise_access/apps/content_assignments/api.py

@@ -291,7 +291,7 @@ def _get_content_title(assignment_configuration, content_key):
         assignment_configuration.enterprise_customer_uuid,
         content_key,
     )
-    return content_metadata['title']
+    return content_metadata.get('title')
 
 
 def _create_new_assignments(assignment_configuration, learner_emails, content_key, content_quantity):

enterprise_access/apps/subsidy_access_policy/content_metadata_api.py

@@ -8,8 +8,10 @@
 from edx_django_utils.cache import TieredCache
 from requests.exceptions import HTTPError
 
+from enterprise_access.cache_utils import versioned_cache_key
+
 from ..api_client.enterprise_catalog_client import EnterpriseCatalogApiClient
-from .utils import get_versioned_subsidy_client, versioned_cache_key
+from .utils import get_versioned_subsidy_client
 
 logger = logging.getLogger(__name__)
 
@@ -28,6 +30,7 @@ def get_and_cache_content_metadata(enterprise_customer_uuid, content_key, timeou
     cache_key = versioned_cache_key('get_subsidy_content_metadata', enterprise_customer_uuid, content_key)
     cached_response = TieredCache.get_cached_response(cache_key)
     if cached_response.is_found:
+        logger.info(f'cache hit for customer {enterprise_customer_uuid} and content {content_key}')
         return cached_response.value
 
     client = get_versioned_subsidy_client()
@@ -57,6 +60,7 @@ def get_and_cache_catalog_contains_content(enterprise_catalog_uuid, content_key,
     cache_key = versioned_cache_key('contains_content_key', enterprise_catalog_uuid, content_key)
     cached_response = TieredCache.get_cached_response(cache_key)
     if cached_response.is_found:
+        logger.info(f'cache hit for catalog {enterprise_catalog_uuid} and content {content_key}')
         return cached_response.value
 
     try:

enterprise_access/apps/subsidy_access_policy/models.py

@@ -17,6 +17,7 @@
 from enterprise_access.apps.api_client.lms_client import LmsApiClient
 from enterprise_access.apps.content_assignments import api as assignments_api
 from enterprise_access.apps.content_assignments.constants import LearnerContentAssignmentStateChoices
+from enterprise_access.cache_utils import request_cache, versioned_cache_key
 from enterprise_access.utils import is_none, is_not_none
 
 from ..content_assignments.models import AssignmentConfiguration
@@ -44,15 +45,10 @@
     SubsidyAPIHTTPError
 )
 from .subsidy_api import get_and_cache_transactions_for_learner
-from .utils import (
-    ProxyAwareHistoricalRecords,
-    create_idempotency_key_for_transaction,
-    get_versioned_subsidy_client,
-    request_cache,
-    versioned_cache_key
-)
+from .utils import ProxyAwareHistoricalRecords, create_idempotency_key_for_transaction, get_versioned_subsidy_client
 
-POLICY_LOCK_RESOURCE_NAME = "subsidy_access_policy"
+REQUEST_CACHE_NAMESPACE = 'subsidy_access_policy'
+POLICY_LOCK_RESOURCE_NAME = 'subsidy_access_policy'
 logger = logging.getLogger(__name__)
 
 
@@ -296,7 +292,7 @@ def subsidy_record(self):
             self.enterprise_customer_uuid,
             self.subsidy_uuid,
         )
-        cached_response = request_cache().get_cached_response(cache_key)
+        cached_response = request_cache(namespace=REQUEST_CACHE_NAMESPACE).get_cached_response(cache_key)
         if cached_response.is_found:
             logger.info(
                 'subsidy_record cache hit '
@@ -311,7 +307,7 @@ def subsidy_record(self):
             logger.warning('SubsidyAccessPolicy.subsidy_record() raised HTTPError: %s', exc)
             result = {}
 
-        request_cache().set(cache_key, result)
+        request_cache(namespace=REQUEST_CACHE_NAMESPACE).set(cache_key, result)
 
         logger.info(
             'subsidy_record cache miss '

enterprise_access/apps/subsidy_access_policy/subsidy_api.py

@@ -8,11 +8,15 @@
 
 import requests
 
+from enterprise_access.cache_utils import request_cache, versioned_cache_key
+
 from .exceptions import SubsidyAPIHTTPError
-from .utils import get_versioned_subsidy_client, request_cache, versioned_cache_key
+from .utils import get_versioned_subsidy_client
 
 logger = logging.getLogger(__name__)
 
+REQUEST_CACHE_NAMESPACE = 'subsidy_access_policy'
+
 
 class TransactionPolicyMismatchError(Exception):
     """
@@ -32,8 +36,9 @@ def get_and_cache_transactions_for_learner(subsidy_uuid, lms_user_id):
     include transactions from multiple access policies.
     """
     cache_key = learner_transaction_cache_key(subsidy_uuid, lms_user_id)
-    cached_response = request_cache().get_cached_response(cache_key)
+    cached_response = request_cache(namespace=REQUEST_CACHE_NAMESPACE).get_cached_response(cache_key)
     if cached_response.is_found:
+        logger.info(f'cache hit for subsidy {subsidy_uuid} and user {lms_user_id}')
         return cached_response.value
 
     client = get_versioned_subsidy_client()
@@ -65,7 +70,7 @@ def get_and_cache_transactions_for_learner(subsidy_uuid, lms_user_id):
         lms_user_id,
         len(result['transactions']),
     )
-    request_cache().set(cache_key, result)
+    request_cache(namespace=REQUEST_CACHE_NAMESPACE).set(cache_key, result)
     return result
 
 

enterprise_access/apps/subsidy_access_policy/utils.py

@@ -5,15 +5,9 @@
 
 from django.apps import apps
 from django.conf import settings
-from edx_django_utils.cache import RequestCache
 from edx_enterprise_subsidy_client import get_enterprise_subsidy_api_client
 from simple_history.models import HistoricalRecords, registered_models
 
-from enterprise_access import __version__ as code_version
-
-CACHE_KEY_SEP = ':'
-CACHE_NAMESPACE = 'subsidy_access_policy'
-
 LEDGERED_SUBSIDY_IDEMPOTENCY_KEY_PREFIX = 'ledger-for-subsidy'
 TRANSACTION_METADATA_KEYS = {
     'lms_user_id',
@@ -34,27 +28,6 @@ def get_versioned_subsidy_client():
     return get_enterprise_subsidy_api_client(**kwargs)
 
 
-def versioned_cache_key(*args):
-    """
-    Utility to produce a versioned cache key, which includes
-    an optional settings variable and the current code version,
-    so that we can perform key-based cache invalidation.
-    """
-    components = [str(arg) for arg in args]
-    components.append(code_version)
-    if stamp_from_settings := getattr(settings, 'CACHE_KEY_VERSION_STAMP', None):
-        components.append(stamp_from_settings)
-    decoded_cache_key = CACHE_KEY_SEP.join(components)
-    return hashlib.sha512(decoded_cache_key.encode()).hexdigest()
-
-
-def request_cache():
-    """
-    Helper that returns a namespaced RequestCache instance.
-    """
-    return RequestCache(namespace=CACHE_NAMESPACE)
-
-
 def create_idempotency_key_for_transaction(subsidy_uuid, **metadata):
     """
     Create a key that allows a transaction to be created idempotently.

enterprise_access/cache_utils.py

@@ -0,0 +1,33 @@
+"""
+Utils for interacting with cache interfaces.
+"""
+import hashlib
+
+from django.conf import settings
+from edx_django_utils.cache import RequestCache
+
+from enterprise_access import __version__ as code_version
+
+CACHE_KEY_SEP = ':'
+DEFAULT_NAMESPACE = 'enterprise-access-default'
+
+
+def versioned_cache_key(*args):
+    """
+    Utility to produce a versioned cache key, which includes
+    an optional settings variable and the current code version,
+    so that we can perform key-based cache invalidation.
+    """
+    components = [str(arg) for arg in args]
+    components.append(code_version)
+    if stamp_from_settings := getattr(settings, 'CACHE_KEY_VERSION_STAMP', None):
+        components.append(stamp_from_settings)
+    decoded_cache_key = CACHE_KEY_SEP.join(components)
+    return hashlib.sha512(decoded_cache_key.encode()).hexdigest()
+
+
+def request_cache(namespace=DEFAULT_NAMESPACE):
+    """
+    Helper that returns a namespaced RequestCache instance.
+    """
+    return RequestCache(namespace=namespace)