corrected relogin logic

inventory_provider/db/ims.py

+import json
+
 import requests
 import time
 
@@ -55,13 +57,14 @@ class IMS(object):
     cache = {}
     base_url = None
     bearer_token = None
-    bearer_token_init_time = None
+    bearer_token_init_time = 0
     reconnect_attempts = 0
 
-    def __init__(self, base_url, username, password):
+    def __init__(self, base_url, username, password, bearer_token=None):
         IMS.base_url = base_url
         self.username = username
         self.password = password
+        IMS.bearer_token = bearer_token
 
     @classmethod
     def _init_bearer_token(cls, username, password):
@@ -69,14 +72,14 @@ class IMS(object):
         if not cls.bearer_token or \
                 re_init_time - cls.bearer_token_init_time \
                 > cls.TIMEOUT_THRESHOLD:
-            IMS.reconnect_attempts = 0
+            cls.reconnect_attempts = 0
         else:
             cls.reconnect_attempts += 1
             if cls.reconnect_attempts > cls.PERMITTED_RECONNECT_ATTEMPTS:
                 raise IMSError('Too many reconnection attempts made')
 
         response = requests.post(
-            IMS.base_url + IMS.LOGIN_PATH,
+            cls.base_url + cls.LOGIN_PATH,
             auth=(username, password))
         response.raise_for_status()
         cls.bearer_token_init_time = re_init_time
@@ -109,23 +112,33 @@ class IMS(object):
         if not IMS.bearer_token:
             self._init_bearer_token(self.username, self.password)
 
-        make_request = True
-        while make_request:
+        def _is_invalid_login_state(response_):
+            if response_.status_code == requests.codes.unauthorized:
+                return True
+
+            if response_.status_code == requests.codes.ok:
+                j = response_.json()
+                if j and isinstance(j, dict) and \
+                        j.get('HasErrors', False) and 'guid expired' in \
+                        j['Errors'][0]['ErrorMessage'].lower():
+                    return True
+
+            return False
+
+        while True:
             response = requests.get(
                 url,
                 headers={'Authorization': self.bearer_token},
                 params=params)
-            if response.status_code == requests.codes.unauthorized:
+            if _is_invalid_login_state(response):
                 IMS._init_bearer_token(self.username, self.password)
             else:
-                make_request = False
+                response.raise_for_status()
+                return_value = response.json()
 
-        response.raise_for_status()
-        return_value = response.json()
-
-        if use_cache:
-            IMS.cache[cache_key] = return_value
-        return return_value
+                if use_cache:
+                    IMS.cache[cache_key] = return_value
+                return return_value
 
     def get_entity_by_id(
             self,
@@ -168,7 +181,8 @@ class IMS(object):
                 use_cache)
             more_to_come = False
             if entities:
-                more_to_come = len(entities) >= IMS.NO_OF_ELEMENTS_PER_ITERATION
+                more_to_come = \
+                    len(entities) >= IMS.NO_OF_ELEMENTS_PER_ITERATION
                 start_entity += IMS.NO_OF_ELEMENTS_PER_ITERATION
                 yield from entities