retry on ratelimit

Added a retry_on_ratelimit parameter to the Connection
class so that ratelimited requests can be retried.

DocImpact

Change-Id: I2817a7ea0ed2d69a7659e80111fbd2c91a75d530

swiftclient/client.py

@@ -1035,7 +1035,8 @@ class Connection(object):
                  preauthurl=None, preauthtoken=None, snet=False,
                  starting_backoff=1, max_backoff=64, tenant_name=None,
                  os_options=None, auth_version="1", cacert=None,
-                 insecure=False, ssl_compression=True):
+                 insecure=False, ssl_compression=True,
+                 retry_on_ratelimit=False):
         """
         :param authurl: authentication URL
         :param user: user name to authenticate as
@@ -1061,6 +1062,10 @@ class Connection(object):
                                 present an attempt to disable SSL compression
                                 will be made. This may provide a performance
                                 increase for https upload/download operations.
+        :param retry_on_ratelimit: by default, a ratelimited connection will
+                                   raise an exception to the caller. Setting
+                                   this parameter to True will cause a retry
+                                   after a backoff.
         """
         self.authurl = authurl
         self.user = user
@@ -1081,6 +1086,7 @@ class Connection(object):
         self.insecure = insecure
         self.ssl_compression = ssl_compression
         self.auth_end_time = 0
+        self.retry_on_ratelimit = retry_on_ratelimit
 
     def close(self):
         if self.http_conn and type(self.http_conn) is tuple\
@@ -1154,6 +1160,8 @@ class Connection(object):
                     self.http_conn = None
                 elif 500 <= err.http_status <= 599:
                     pass
+                elif self.retry_on_ratelimit and err.http_status == 498:
+                    pass
                 else:
                     logger.exception(err)
                     raise

tests/test_swiftclient.py

@@ -713,6 +713,24 @@ class TestConnection(MockHttpTest):
         self.assertRaises(c.ClientException, conn.head_account)
         self.assertEqual(conn.attempts, conn.retries + 1)
 
+    def test_retry_on_ratelimit(self):
+        c.http_connection = self.fake_http_connection(498)
+
+        def quick_sleep(*args):
+            pass
+        c.sleep = quick_sleep
+
+        # test retries
+        conn = c.Connection('http://www.test.com', 'asdf', 'asdf',
+                            retry_on_ratelimit=True)
+        self.assertRaises(c.ClientException, conn.head_account)
+        self.assertEqual(conn.attempts, conn.retries + 1)
+
+        # test default no-retry
+        conn = c.Connection('http://www.test.com', 'asdf', 'asdf')
+        self.assertRaises(c.ClientException, conn.head_account)
+        self.assertEqual(conn.attempts, 1)
+
     def test_resp_read_on_server_error(self):
         c.http_connection = self.fake_http_connection(500)
         conn = c.Connection('http://www.test.com', 'asdf', 'asdf', retries=0)