Adds util functions for polling against redis cache.

apps/cic-ussd/cic_ussd/processor/util.py

@@ -1,15 +1,22 @@
 # standard imports
 import datetime
 import json
+import logging
+import time
+from typing import Union
 
 # external imports
+from cic_types.condiments import MetadataPointer
 from cic_types.models.person import get_contact_data_from_vcard
 from tinydb.table import Document
 
 # local imports
+from cic_ussd.cache import cache_data_key, get_cached_data
 from cic_ussd.menu.ussd_menu import UssdMenu
 from cic_ussd.translation import translation_for
 
+logg = logging.getLogger(__file__)
+
 
 def latest_input(user_input: str) -> str:
     """
@@ -76,3 +83,66 @@ def resume_last_ussd_session(last_state: str) -> Document:
     if last_state in non_reusable_states:
         return UssdMenu.find_by_name('start')
     return UssdMenu.find_by_name(last_state)
+
+
+def wait_for_cache(identifier: Union[list, bytes], resource_name: str, salt: MetadataPointer, interval: int = 1, max_retry: int = 5):
+    """
+    :param identifier:
+    :type identifier:
+    :param interval:
+    :type interval:
+    :param resource_name:
+    :type resource_name:
+    :param salt:
+    :type salt:
+    :param max_retry:
+    :type max_retry:
+    :return:
+    :rtype:
+    """
+    key = cache_data_key(identifier=identifier, salt=salt)
+    resource = get_cached_data(key)
+    counter = 0
+    while resource is None:
+        logg.debug(f'Waiting for: {resource_name} at: {key}. Checking after: {interval} ...')
+        time.sleep(interval)
+        counter += 1
+        resource = get_cached_data(key)
+        if resource is not None:
+            logg.debug(f'{resource_name} now available.')
+            break
+        else:
+            if counter == max_retry:
+                logg.debug(f'Could not find: {resource_name} within: {max_retry}')
+                break
+
+
+def wait_for_session_data(resource_name: str, session_data_key: str, ussd_session: dict, interval: int = 1, max_retry: int = 5):
+    """
+    :param interval:
+    :type interval:
+    :param resource_name:
+    :type resource_name:
+    :param session_data_key:
+    :type session_data_key:
+    :param ussd_session:
+    :type ussd_session:
+    :param max_retry:
+    :type max_retry:
+    :return:
+    :rtype:
+    """
+    session_data = ussd_session.get('data').get(session_data_key)
+    counter = 0
+    while session_data is None:
+        logg.debug(f'Waiting for: {resource_name}. Checking after: {interval} ...')
+        time.sleep(interval)
+        counter += 1
+        session_data = ussd_session.get('data').get(session_data_key)
+        if session_data is not None:
+            logg.debug(f'{resource_name} now available.')
+            break
+        else:
+            if counter == max_retry:
+                logg.debug(f'Could not find: {resource_name} within: {max_retry}')
+                break