+
+
+def check_http_response_success(result):
+ """Convert a 'requests' response to a loop control flag.
+
+ Pass this method a requests.Response object. It returns True if
+ the response indicates success, None if it indicates temporary
+ failure, and False otherwise. You can use this as the
+ success_check for a RetryLoop.
+
+ Implementation details:
+ * Any 2xx result returns True.
+ * A select few status codes, or any malformed responses, return None.
+ 422 Unprocessable Entity is in this category. This may not meet the
+ letter of the HTTP specification, but the Arvados API server will
+ use it for various server-side problems like database connection
+ errors.
+ * Everything else returns False. Note that this includes 1xx and
+ 3xx status codes. They don't indicate success, and you can't
+ retry those requests verbatim.
+ """
+ try:
+ status = result.status_code
+ except Exception:
+ return None
+ if status in _HTTP_SUCCESSES:
+ return True
+ elif status in _HTTP_CAN_RETRY:
+ return None
+ elif 100 <= status < 600:
+ return False
+ else:
+ return None # Get well soon, server.
+
+def retry_method(orig_func):
+ """Provide a default value for a method's num_retries argument.
+
+ This is a decorator for instance and class methods that accept a
+ num_retries argument, with a None default. When the method is called
+ without a value for num_retries, it will be set from the underlying
+ instance or class' num_retries attribute.
+ """
+ @functools.wraps(orig_func)
+ def num_retries_setter(self, *args, **kwargs):
+ arg_vals = inspect.getcallargs(orig_func, self, *args, **kwargs)
+ if arg_vals['num_retries'] is None:
+ kwargs['num_retries'] = self.num_retries
+ return orig_func(self, *args, **kwargs)
+ return num_retries_setter