Docserver: Convert more future Get calls to Thens

chrome/common/extensions/docs/server2/path_canonicalizer.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 collections import defaultdict
 import posixpath
 
 from future import Future
 from path_util import SplitParent
 from special_paths import SITE_VERIFICATION_FILE
@@ skipping 20 matching lines @@
                object_store_creator,
                strip_extensions):
     # |strip_extensions| is a list of file extensions (e.g. .html) that should
     # be stripped for a path's canonical form.
     self._cache = object_store_creator.Create(
         PathCanonicalizer, category=file_system.GetIdentity())
     self._file_system = file_system
     self._strip_extensions = strip_extensions
 
   def _LoadCache(self):
-    cached_future = self._cache.GetMulti(('canonical_paths',
-                                          'simplified_paths_map'))
-
-    def resolve():
+    def resolve(cached):

[ahernandez, 2014/09/03 19:16:07]

Nit: choose a better name for this, like load.

       # |canonical_paths| is the pre-calculated set of canonical paths.
       # |simplified_paths_map| is a lazily populated mapping of simplified file
       # names to a list of full paths that contain them. For example,
       #  - browseraction: [extensions/browserAction.html]
       #  - storage: [apps/storage.html, extensions/storage.html]
-      cached = cached_future.Get()
       canonical_paths, simplified_paths_map = (
           cached.get('canonical_paths'), cached.get('simplified_paths_map'))
 
       if canonical_paths is None:
         assert simplified_paths_map is None
         canonical_paths = set()
         simplified_paths_map = defaultdict(list)
         for base, dirs, files in self._file_system.Walk(''):
           for path in dirs + files:
             path_without_ext, ext = posixpath.splitext(path)
             canonical_path = posixpath.join(base, path_without_ext)
             if (ext not in self._strip_extensions or
                 path == SITE_VERIFICATION_FILE):
               canonical_path += ext
             canonical_paths.add(canonical_path)
             simplified_paths_map[_Normalize(path, splittext=True)].append(
                 canonical_path)
         # Store |simplified_paths_map| sorted. Ties in length are broken by
         # taking the shortest, lexicographically smallest path.
         for path_list in simplified_paths_map.itervalues():
           path_list.sort(key=lambda p: (len(p), p))
         self._cache.SetMulti({
           'canonical_paths': canonical_paths,
           'simplified_paths_map': simplified_paths_map,
         })
       else:
         assert simplified_paths_map is not None
 
       return canonical_paths, simplified_paths_map
+    return self._cache.GetMulti(('canonical_paths',
+                                 'simplified_paths_map')).Then(resolve)
 
-    return Future(callback=resolve)
 
   def Canonicalize(self, path):
     '''Returns the canonical path for |path|.
     '''
     canonical_paths, simplified_paths_map = self._LoadCache().Get()
 
     # Path may already be the canonical path.
     if path in canonical_paths:
       return path
 
@@ skipping 20 matching lines @@
     max_prefix_length = len(_CommonNormalizedPrefix(max_prefix, path))
     for path_for_file in potential_paths[1:]:
       prefix_length = len(_CommonNormalizedPrefix(path_for_file, path))
       if prefix_length > max_prefix_length:
         max_prefix, max_prefix_length = path_for_file, prefix_length
 
     return max_prefix
 
   def Cron(self):
     return self._LoadCache()