Retry fetching patch from rietveld on a 404

rietveld.py

 # coding: utf-8
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """Defines class Rietveld to easily access a rietveld instance.
 
 Security implications:
 
 The following hypothesis are made:
 - Rietveld enforces:
@@ skipping 79 matching lines @@
 
     Converts any CRLF into LF and strip extraneous whitespace.
     """
     return '\n'.join(self.get('/%d/description' % issue).strip().splitlines())
 
   def get_issue_properties(self, issue, messages):
     """Returns all the issue's metadata as a dictionary."""
     url = '/api/%d' % issue
     if messages:
       url += '?messages=true'
-    data = json.loads(self.get(url))
+    data = json.loads(self.get(url, retry_on_404=True))
     data['description'] = '\n'.join(data['description'].strip().splitlines())
     return data
 
   def get_patchset_properties(self, issue, patchset):
     """Returns the patchset properties."""
     url = '/api/%d/%d' % (issue, patchset)
     return json.loads(self.get(url))
 
   def get_file_content(self, issue, patchset, item):
     """Returns the content of a new file.
@@ skipping 271 matching lines @@
     return data['jobs'], data['cursor']
 
   def get(self, request_path, **kwargs):
     kwargs.setdefault('payload', None)
     return self._send(request_path, **kwargs)
 
   def post(self, request_path, data, **kwargs):
     ctype, body = upload.EncodeMultipartFormData(data, [])
     return self._send(request_path, payload=body, content_type=ctype, **kwargs)
 
-  def _send(self, request_path, **kwargs):
+  def _send(self, request_path, retry_on_404=False, **kwargs):
     """Sends a POST/GET to Rietveld.  Returns the response body."""
     # rpc_server.Send() assumes timeout=None by default; make sure it's set
     # to something reasonable.
     kwargs.setdefault('timeout', 15)
     logging.debug('POSTing to %s, args %s.', request_path, kwargs)
     try:
       # Sadly, upload.py calls ErrorExit() which does a sys.exit(1) on HTTP
       # 500 in AbstractRpcServer.Send().
       old_error_exit = upload.ErrorExit
       def trap_http_500(msg):
@@ skipping 10 matching lines @@
       for retry in xrange(maxtries):
         try:
           logging.debug('%s' % request_path)
           result = self.rpc_server.Send(request_path, **kwargs)
           # Sometimes GAE returns a HTTP 200 but with HTTP 500 as the content.
           # How nice.
           return result
         except urllib2.HTTPError, e:
           if retry >= (maxtries - 1):
             raise
-          if e.code not in (500, 502, 503):
+          flake_codes = [500, 502, 503]
+          if retry_on_404:
+            flake_codes.append(404)
+          if e.code not in flake_codes:
             raise
         except urllib2.URLError, e:
           if retry >= (maxtries - 1):
             raise
           if (not 'Name or service not known' in e.reason and
               not 'EOF occurred in violation of protocol' in e.reason):
             # Usually internal GAE flakiness.
             raise
         except ssl.SSLError, e:
           if retry >= (maxtries - 1):
@@ skipping 283 matching lines @@
   def trigger_try_jobs(  # pylint:disable=R0201
       self, issue, patchset, reason, clobber, revision, builders_and_tests,
       master=None):
     logging.info('ReadOnlyRietveld: triggering try jobs %r for issue %d' %
         (builders_and_tests, issue))
 
   def trigger_distributed_try_jobs(  # pylint:disable=R0201
       self, issue, patchset, reason, clobber, revision, masters):
     logging.info('ReadOnlyRietveld: triggering try jobs %r for issue %d' %
         (masters, issue))