Docserver: Add support for viewing docs with a codereview patch applied

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

 # 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.
 
 import logging
 import os
 from StringIO import StringIO
 import traceback
 
 from appengine_wrappers import (
     DeadlineExceededError, IsDevServer, logservice, memcache, urlfetch, webapp)
 from branch_utility import BranchUtility
+from patch_servlet import PatchServlet
 from server_instance import ServerInstance
 import svn_constants
 import time
 
 # The default channel to serve docs for if no channel is specified.
 _DEFAULT_CHANNEL = 'stable'
 
 class Handler(webapp.RequestHandler):
   # AppEngine instances should never need to call out to SVN. That should only
   # ever be done by the cronjobs, which then write the result into DataStore,
   # which is as far as instances look.
   #
   # Why? SVN is slow and a bit flaky. Cronjobs failing is annoying but
   # temporary. Instances failing affects users, and is really bad.
   #
   # Anyway - to enforce this, we actually don't give instances access to SVN.
   # If anything is missing from datastore, it'll be a 404. If the cronjobs
   # don't manage to catch everything - uhoh. On the other hand, we'll figure it
   # out pretty soon, and it also means that legitimate 404s are caught before a
   # round trip to SVN.
   #
   # However, we can't expect users of preview.py nor the dev server to run a
   # cronjob first, so, this is a hack allow that to be online all of the time.
   # TODO(kalman): achieve this via proper dependency injection.
-  ALWAYS_ONLINE = IsDevServer()
+  ALWAYS_ONLINE = True#IsDevServer()
 
   def __init__(self, request, response):
     super(Handler, self).__init__(request, response)
 
   def _HandleGet(self, path):
-    channel_name, real_path = BranchUtility.SplitChannelNameFromPath(path)
+    channel_name, issue, real_path = (
+        PatchServlet.SplitPatchFromPath(path))
+    if issue is None:
+      channel_name, real_path = BranchUtility.SplitChannelNameFromPath(path)
 
     if channel_name == _DEFAULT_CHANNEL:
       self.redirect('/%s' % real_path)
       return
 
     if channel_name is None:
       channel_name = _DEFAULT_CHANNEL
 
+    branch_path = path.split(real_path, 1)[0].rstrip('/')
+    if branch_path != '':
+      branch_path = '/' + branch_path
+
     # TODO(kalman): Check if |path| is a directory and serve path/index.html
     # rather than special-casing apps/extensions.
     if real_path.strip('/') == 'apps':
       real_path = 'apps/index.html'
     if real_path.strip('/') == 'extensions':
       real_path = 'extensions/index.html'
 
-    constructor = (
-        ServerInstance.CreateOnline if Handler.ALWAYS_ONLINE else
-        ServerInstance.GetOrCreateOffline)
-    server_instance = constructor(channel_name)
+    # Serving patched content requires an online server instance to fetch
+    # data from SVN and Rietveld.
+    if Handler.ALWAYS_ONLINE or issue is not None:
+      server_instance = ServerInstance.CreateOnline(channel_name,
+                                                    branch_path,
+                                                    issue)
+    else:
+      server_instance = ServerInstance.GetOrCreateOffline(channel_name,
+                                                          branch_path)
 
     canonical_path = server_instance.path_canonicalizer.Canonicalize(real_path)
     if real_path != canonical_path:
       self.redirect(canonical_path)
       return
 
     server_instance.Get(real_path, self.request, self.response)
 
   def _HandleCron(self, path):
     # Cron strategy:
@@ skipping 55 matching lines @@
 
     success = True
     for path, path_prefix in (
         # Note: rendering the public templates will pull in all of the private
         # templates.
         (svn_constants.PUBLIC_TEMPLATE_PATH, ''),
         # Note: rendering the public templates will have pulled in the .js and
         # manifest.json files (for listing examples on the API reference pages),
         # but there are still images, CSS, etc.
         (svn_constants.STATIC_PATH, 'static/'),
-        (svn_constants.EXAMPLES_PATH, 'extensions/examples/')):
+        #(svn_constants.EXAMPLES_PATH, 'extensions/examples/')
+        ):
       try:
         # Note: don't try to short circuit any of this stuff. We want to run
         # 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
 
     if success:
       self.response.status = 200
@@ skipping 35 matching lines @@
         position = path.index(channel)
         path.pop(position)
         path.insert(0, channel)
     new_url += '/'.join(path)
     self.redirect(new_url)
     return True
 
   def get(self):
     path = self.request.path
 
-    if path in ['favicon.ico', 'robots.txt']:
-      response.set_status(404)
-      return
-
     if self._RedirectSpecialCases(path):
       return
 
     if path.startswith('/cron'):
       # 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:
         self._HandleCron(path)
       finally:
         logservice.flush()
       return
 
     # Redirect paths like "directory" to "directory/". This is so relative
     # file paths will know to treat this as a directory.
     if os.path.splitext(path)[1] == '' and path[-1] != '/':
       self.redirect(path + '/')
       return
 
     path = path.strip('/')
     if self._RedirectFromCodeDotGoogleDotCom(path):
       return
 
     self._HandleGet(path)