Docserver: achieve online vs offline (cron vs instance) behaviour at the object

chrome/common/extensions/docs/server2/cron_servlet.py

 # Copyright 2013 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.
 
 import logging
 import time
 import traceback
 
 from appengine_wrappers import DeadlineExceededError, logservice
 from branch_utility import BranchUtility
 from render_servlet import RenderServlet
 from server_instance import ServerInstance
 from servlet import Servlet, Request, Response
 import svn_constants
 
 class CronServlet(Servlet):
   '''Servlet which runs a cron job.
   '''
-  def Get(self):
+  def Get(self, server_instance=None):
     # Crons often time out, and when they do *and* then eventually try to
     # flush logs they die. Turn off autoflush and manually do so at the end.
     logservice.AUTOFLUSH_ENABLED = False
     try:
-      return self._GetImpl()
+      return self._GetImpl(server_instance)
     finally:
       logservice.flush()
 
-  def _GetImpl(self):
+  def _GetImpl(self, server_instance):
     # Cron strategy:
     #
     # Find all public template files and static files, and render them. Most of
     # the time these won't have changed since the last cron run, so it's a
     # little wasteful, but hopefully rendering is really fast (if it isn't we
     # have a problem).
     channel = self._request.path.strip('/')
     logging.info('cron/%s: starting' % channel)
 
-    server_instance = ServerInstance.CreateOnline(channel)
+    if server_instance is None:
+      server_instance = ServerInstance.CreateOnline(channel)
 
     def run_cron_for_dir(d, path_prefix=''):
       success = True
       start_time = time.time()
       files = [f for f in server_instance.content_cache.GetFromFileListing(d)
                if not f.endswith('/')]
       logging.info('cron/%s: rendering %s files from %s...' % (
           channel, len(files), d))
       try:
         for i, f in enumerate(files):
@@ skipping 35 matching lines @@
         # the cron for all the directories regardless of intermediate failures.
         success = run_cron_for_dir(path, path_prefix=path_prefix) and success
       except DeadlineExceededError:
         success = False
         break
 
     logging.info('cron/%s: finished' % channel)
 
     return (Response.Ok('Success') if success else
             Response.InternalError('Failure'))