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

chrome/common/extensions/docs/server2/patch_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.
+
+from appengine_url_fetcher import AppEngineUrlFetcher
+from caching_file_system import CachingFileSystem
+from caching_rietveld_patcher import CachingRietveldPatcher
+from chained_compiled_file_system import ChainedCompiledFileSystem
+from compiled_file_system import  CompiledFileSystem
+from instance_servlet import InstanceServlet
+from render_servlet import RenderServlet
+from rietveld_patcher import RietveldPatcher, RietveldPatcherError
+from object_store_creator import ObjectStoreCreator
+from patched_file_system import PatchedFileSystem
+from server_instance import ServerInstance
+from servlet import Request, Response, Servlet
+import svn_constants
+import url_constants
+
+class _PatchServletDelegate(RenderServlet.Delegate):
+  def __init__(self, issue, delegate):
+    self._issue = issue
+    self._delegate = delegate
+
+  def CreateServerInstanceForChannel(self, channel):
+    base_object_store_creator = ObjectStoreCreator(channel,
+                                                   start_empty=False)
+    # TODO(fj): Use OfflineFileSystem here once all json/idl files in api/
+    # are pulled into data store by cron jobs.
+    base_file_system = CachingFileSystem(
+        self._delegate.CreateHostFileSystemForBranch(channel),
+        base_object_store_creator)
+    base_compiled_fs_factory = CompiledFileSystem.Factory(
+        base_file_system, base_object_store_creator)
+
+    object_store_creator = ObjectStoreCreator('trunk@%s' % self._issue,
+                                              start_empty=False)
+    rietveld_patcher = CachingRietveldPatcher(
+        RietveldPatcher(svn_constants.EXTENSIONS_PATH,
+                        self._issue,
+                        AppEngineUrlFetcher(url_constants.CODEREVIEW_SERVER)),
+        object_store_creator)
+    patched_file_system = PatchedFileSystem(base_file_system,
+                                            rietveld_patcher)
+    patched_compiled_fs_factory = CompiledFileSystem.Factory(
+        patched_file_system, object_store_creator)
+
+    compiled_fs_factory = ChainedCompiledFileSystem.Factory(
+        [(patched_compiled_fs_factory, patched_file_system),
+         (base_compiled_fs_factory, base_file_system)])
+    return ServerInstance(channel,
+                          object_store_creator,
+                          patched_file_system,
+                          self._delegate.CreateAppSamplesFileSystem(
+                              object_store_creator),
+                          '/_patch/%s/static' % self._issue,
+                          compiled_fs_factory)
+
+class PatchServlet(Servlet):
+  '''Servlet which renders patched docs.
+  '''
+  def __init__(self, request, delegate=None):
+    self._request = request
+    self._delegate = delegate or InstanceServlet.Delegate()
+
+  def Get(self):
+    path_with_issue = self._request.path.lstrip('/')
+    if '/' in path_with_issue:
+      issue, real_path = path_with_issue.split('/', 1)
+    else:
+      return Response.NotFound('Malformed URL. It should look like ' +
+          'https://developer.chrome.com/_patch/12345/extensions/...')
+
+    fake_path = '/trunk/%s' % real_path
+
+    try:
+      response = RenderServlet(
+          Request(fake_path, self._request.host, self._request.headers),
+          _PatchServletDelegate(issue, self._delegate)).Get()
+      # Disable cache for patched content.
+      response.headers.pop('cache-control', None)
+    except RietveldPatcherError as e:
+      response = Response.NotFound(e.message, {'Content-Type': 'text/plain'})
+
+    redirect_url, permanent = response.GetRedirect()
+    if redirect_url is not None:
+      if redirect_url.startswith('/trunk/'):
+        redirect_url = redirect_url.split('/trunk', 1)[1]
+      response = Response.Redirect('/_patch/%s%s' % (issue, redirect_url),
+                                   permanent)
+    return response