Implement retries in 'git-obs'

osc/gitea_api/connection.py

@@ -1,18 +1,17 @@
 import copy
 import http.client
 import json
+import time
 import urllib.parse
 from typing import Optional
 
 import urllib3
+import urllib3.exceptions
 import urllib3.response
 
 from .conf import Login
 
 
-# TODO: retry, backoff, connection pool?
-
-
 class GiteaHTTPResponse:
     """
     A ``urllib3.response.HTTPResponse`` wrapper
@@ -52,6 +51,16 @@ class Connection:
         self.port = alternative_port if alternative_port else parsed_url.port
         self.conn = ConnectionClass(host=self.host, port=self.port)
 
+        # retries; variables are named according to urllib3
+        self.retry_count = 3
+        self.retry_backoff_factor = 2
+        self.retry_status_forcelist = (
+            500,  # Internal Server Error
+            502,  # Bad Gateway
+            503,  # Service Unavailable
+            504,  # Gateway Timeout
+        )
+
         if hasattr(self.conn, "set_cert"):
             # needed to avoid: AttributeError: 'HTTPSConnection' object has no attribute 'assert_hostname'. Did you mean: 'server_hostname'?
             self.conn.set_cert()
@@ -95,9 +104,28 @@ class Connection:
 
         body = json.dumps(json_data) if json_data else None
 
+        for retry in range(1 + self.retry_count):
+            # 1 regular request + ``self.retry_count`` retries
+            try:
                 self.conn.request(method, url, body, headers)
                 response = self.conn.getresponse()
 
+                if response.status not in self.retry_status_forcelist:
+                    # we are happy with the response status -> use the response
+                    break
+
+                if retry >= self.retry_count:
+                    # we have reached maximum number of retries -> use the response
+                    break
+
+            except (urllib3.exceptions.HTTPError, ConnectionResetError):
+                if retry >= self.retry_count:
+                    raise
+
+            # {backoff factor} * (2 ** ({number of previous retries}))
+            time.sleep(self.retry_backoff_factor * (2 ** retry))
+            self.conn.close()
+
         if isinstance(response, http.client.HTTPResponse):
             result = GiteaHTTPResponse(urllib3.response.HTTPResponse.from_httplib(response))
         else: