Docs: Use ETags.

chrome/common/extensions/docs/server2/content_provider.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 mimetypes
 import posixpath
 
 from compiled_file_system import SingleFile
 from directory_zipper import DirectoryZipper
 from docs_server_utils import ToUnicode
 from file_system import FileNotFoundError
 from future import Future
 from path_canonicalizer import PathCanonicalizer
 from path_util import AssertIsValid, Join, ToDirectory
 from special_paths import SITE_VERIFICATION_FILE
 from third_party.handlebar import Handlebar
 from third_party.markdown import markdown
 
 
 _MIMETYPE_OVERRIDES = {
   # SVG is not supported by mimetypes.guess_type on AppEngine.
   '.svg': 'image/svg+xml',
 }
 
 
 class ContentAndType(object):
   '''Return value from ContentProvider.GetContentAndType.
   '''
 
-  def __init__(self, content, content_type):
+  def __init__(self, content, content_type, version):
     self.content = content
     self.content_type = content_type
+    self.version = version
 
 
 class ContentProvider(object):
   '''Returns file contents correctly typed for their content-types (in the HTTP
   sense). Content-type is determined from Python's mimetype library which
   guesses based on the file extension.
 
   Typically the file contents will be either str (for binary content) or
   unicode (for text content). However, HTML files *may* be returned as
   Handlebar templates (if |supports_templates| is True on construction), in
@@ skipping 50 matching lines @@
       mimetype = 'text/plain'
     elif mimetype == 'text/html':
       content = ToUnicode(text)
       if self._supports_templates:
         content = Handlebar(content, name=path)
     elif (mimetype.startswith('text/') or
           mimetype in ('application/javascript', 'application/json')):
       content = ToUnicode(text)
     else:
       content = text
-    return ContentAndType(content, mimetype)
+    return ContentAndType(content,
+                          mimetype,
+                          self.file_system.Stat(path).version)
 
   def GetCanonicalPath(self, path):
     '''Gets the canonical location of |path|. This class is tolerant of
     spelling errors and missing files that are in other directories, and this
     returns the correct/canonical path for those.
 
     For example, the canonical path of "browseraction" is probably
     "extensions/browserAction.html".
 
     Note that the canonical path is relative to this content provider i.e.
@@ skipping 12 matching lines @@
   def GetContentAndType(self, path):
     '''Returns the ContentAndType of the file at |path|.
     '''
     AssertIsValid(path)
     base, ext = posixpath.splitext(path)
 
     # Check for a zip file first, if zip is enabled.
     if self._directory_zipper and ext == '.zip':
       zip_future = self._directory_zipper.Zip(ToDirectory(base))
       return Future(callback=
-          lambda: ContentAndType(zip_future.Get(), 'application/zip'))
+          lambda: ContentAndType(zip_future.Get(), 'application/zip', None))
 
     # If there is no file extension, look for a file with one of the default
     # extensions.
     #
     # Note that it would make sense to guard this on Exists(path), since a file
     # without an extension may actually exist, but it's such an uncommon case
     # it hardly seems worth the potential performance hit.
     if not ext:
       for default_ext in self._default_extensions:
         if self.file_system.Exists(path + default_ext).Get():
           path += default_ext
           break
 
     return self._content_cache.GetFromFile(path)
 
   def Cron(self):
     futures = [self._path_canonicalizer.Cron()]
     for root, _, files in self.file_system.Walk(''):
       for f in files:
         futures.append(self.GetContentAndType(Join(root, f)))
         # Also cache the extension-less version of the file if needed.
         base, ext = posixpath.splitext(f)
         if f != SITE_VERIFICATION_FILE and ext in self._default_extensions:
           futures.append(self.GetContentAndType(Join(root, base)))
       # TODO(kalman): Cache .zip files for each directory (if supported).
     return Future(callback=lambda: [f.Get() for f in futures])
 
   def __repr__(self):
     return 'ContentProvider of <%s>' % repr(self.file_system)