fix: DB tx isolation and informative license logging

Track license changes in a celery task outside of the DB transaction
block that updates the license state, so that task can read the
committed updates to the license records.
Also add helpful logging to our license assignment/reminder email tasks.
ENT-7795

license_manager/apps/api/tasks.py

@@ -50,6 +50,8 @@
 SOFT_TIME_LIMIT = 900
 MAX_TIME_LIMIT = 960
 
+LICENSE_DEBUG_PREFIX = '[LICENSE DEBUGGING]'
+
 
 class LoggedTaskWithRetry(LoggedTask):  # pylint: disable=abstract-method
     """
@@ -117,10 +119,12 @@ def send_assignment_email_task(custom_template_text, email_recipient_list, subsc
     enterprise_sender_alias = get_enterprise_sender_alias(enterprise_customer)
     enterprise_contact_email = enterprise_customer.get('contact_email')
 
+    pending_license_by_email = {}
     # We need to send these emails individually, because each email's text must be
     # generated for every single user/activation_key
     for pending_license in pending_licenses:
         user_email = pending_license.user_email
+        pending_license_by_email[user_email] = pending_license
         license_activation_key = str(pending_license.activation_key)
         braze_campaign_id = settings.BRAZE_ASSIGNMENT_EMAIL_CAMPAIGN
         braze_trigger_properties = {
@@ -141,6 +145,10 @@ def send_assignment_email_task(custom_template_text, email_recipient_list, subsc
                 recipients=[recipient],
                 trigger_properties=braze_trigger_properties,
             )
+            logger.info(
+                f'{LICENSE_DEBUG_PREFIX} Sent license assignment email '
+                f'braze campaign {braze_campaign_id} to {recipient}'
+            )
         except BrazeClientError as exc:
             message = (
                 'License manager activation email sending received an '
@@ -149,6 +157,13 @@ def send_assignment_email_task(custom_template_text, email_recipient_list, subsc
             logger.exception(message)
             raise exc
 
+    emails_with_no_assignments = [
+        _email for _email in email_recipient_list
+        if _email not in pending_license_by_email
+    ]
+    if emails_with_no_assignments:
+        logger.warning(f'{LICENSE_DEBUG_PREFIX} No assignment email sent for {emails_with_no_assignments}')
+
 
 @shared_task(base=LoggedTaskWithRetry, soft_time_limit=SOFT_TIME_LIMIT, time_limit=MAX_TIME_LIMIT)
 def link_learners_to_enterprise_task(learner_emails, enterprise_customer_uuid):
@@ -189,10 +204,12 @@ def send_reminder_email_task(custom_template_text, email_recipient_list, subscri
     enterprise_sender_alias = get_enterprise_sender_alias(enterprise_customer)
     enterprise_contact_email = enterprise_customer.get('contact_email')
 
+    pending_license_by_email = {}
     # We need to send these emails individually, because each email's text must be
     # generated for every single user/activation_key
     for pending_license in pending_licenses:
         user_email = pending_license.user_email
+        pending_license_by_email[user_email] = pending_license
         license_activation_key = str(pending_license.activation_key)
         braze_campaign_id = settings.BRAZE_REMIND_EMAIL_CAMPAIGN
         braze_trigger_properties = {
@@ -217,7 +234,10 @@ def send_reminder_email_task(custom_template_text, email_recipient_list, subscri
                 recipients=[recipient],
                 trigger_properties=braze_trigger_properties,
             )
-
+            logger.info(
+                f'{LICENSE_DEBUG_PREFIX} Sent license reminder email '
+                f'braze campaign {braze_campaign_id} to {recipient}'
+            )
         except BrazeClientError as exc:
             message = (
                 'Error hitting Braze API. '
@@ -228,6 +248,13 @@ def send_reminder_email_task(custom_template_text, email_recipient_list, subscri
 
     License.set_date_fields_to_now(pending_licenses, ['last_remind_date'])
 
+    emails_with_no_assignments = [
+        _email for _email in email_recipient_list
+        if _email not in pending_license_by_email
+    ]
+    if emails_with_no_assignments:
+        logger.warning(f'{LICENSE_DEBUG_PREFIX} No reminder email sent for {emails_with_no_assignments}')
+
 
 @shared_task(base=LoggedTaskWithRetry)
 def send_post_activation_email_task(enterprise_customer_uuid, user_email):

license_manager/apps/api/v1/views.py

@@ -721,11 +721,6 @@ def _assign_new_licenses(self, subscription_plan, user_emails):
             batch_size=10,
         )
 
-        license_uuid_strs = [str(_license.uuid) for _license in licenses]
-        track_license_changes_task.delay(
-            license_uuid_strs,
-            constants.SegmentEvents.LICENSE_ASSIGNED,
-        )
         return licenses
 
     def _set_source_for_assigned_licenses(self, assigned_licenses, emails_and_sfids):
@@ -844,13 +839,20 @@ def _assign(self, request, subscription_plan):
                 logger.exception(error_message)
                 return Response(error_message, status=status.HTTP_422_UNPROCESSABLE_ENTITY)
             else:
-                notify_users = request.data.get('notify_users', True)
-                custom_template_text = utils.get_custom_text(request.data)
+                # Track license changes and do any other tasks that may want to
+                # read from the License DB table outside of the transaction.atomic() block,
+                # so that they can read the committed and updated versions
+                # of the now-assigned license records.
+                track_license_changes_task.delay(
+                    [str(_license.uuid) for _license in assigned_licenses],
+                    constants.SegmentEvents.LICENSE_ASSIGNED,
+                )
+
                 self._link_and_notify_assigned_emails(
-                    user_emails,
-                    subscription_plan,
-                    notify_users,
-                    custom_template_text
+                    user_emails=user_emails,
+                    subscription_plan=subscription_plan,
+                    notify_users=request.data.get('notify_users', True),
+                    custom_template_text=utils.get_custom_text(request.data),
                 )
         else:
             logger.info('All given emails are already associated with a license.')