Docserver: Convert more future Get calls to Thens

chrome/common/extensions/docs/server2/new_github_file_system.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 json
 import logging
 from cStringIO import StringIO
 import posixpath
 import traceback
 from zipfile import ZipFile
@@ skipping 158 matching lines @@
         logging.warning('Blob for %s was corrupted in blobstore!?' % repo_key)
         return fetch_from_github(version)
 
       return Future(value=repo_zip)
 
     def fetch_from_github(version):
       '''Returns a Future which resolves to the _GithubZipFile for this repo
       fetched new from GitHub, then writes it to blobstore and |version| to the
       stat caches.
       '''
-      github_future = self._fetcher.FetchAsync(
-          'zipball', username=username, password=password)
-      def resolve():
+      def get_zip(github_zip):
         try:
-          blob = github_future.Get().content
+          blob = github_zip.content
         except urlfetch.DownloadError:
           raise FileSystemError('Failed to download repo %s file from %s' %
                                 (repo_key, repo_url))
 
         repo_zip = _GithubZipFile.Create(repo_key, blob)
         if repo_zip is None:
           raise FileSystemError('Blob for %s was fetched corrupted from %s' %
                                 (repo_key, repo_url))
 
         self._blobstore.Set(self._repo_url, blob, _GITHUB_REPOS_NAMESPACE)
         self._up_to_date_cache.Set(repo_key, True)
         self._stat_cache.Set(repo_key, version)
         return repo_zip
-      return Future(callback=resolve)
+      return self._fetcher.FetchAsync(
+          'zipball', username=username, password=password).Then(get_zip)
 
     # To decide whether we need to re-stat, and from there whether to re-fetch,
     # make use of ObjectStore's start-empty configuration. If
     # |object_store_creator| is configured to start empty then our creator
     # wants to refresh (e.g. running a cron), so fetch the live stat from
     # GitHub. If the stat hasn't changed since last time then no reason to
     # re-fetch from GitHub, just take from blobstore.
 
     cached_version = self._stat_cache.Get(repo_key).Get()
     if self._up_to_date_cache.Get(repo_key).Get() is None:
@@ skipping 31 matching lines @@
 
   def Refresh(self):
     return self.ReadSingle('')
 
   def Read(self, paths, skip_not_found=False):
     '''Returns a directory mapping |paths| to the contents of the file at each
     path. If path ends with a '/', it is treated as a directory and is mapped to
     a list of filenames in that directory.
     '''
     self._EnsureRepoZip()
-    def resolve():
-      repo_zip = self._repo_zip.Get()
+    def read(repo_zip):
       reads = {}
       for path in paths:
         if path not in repo_zip.Paths():
           raise FileNotFoundError('"%s": %s not found' % (self._repo_key, path))
         if IsDirectory(path):
           reads[path] = repo_zip.List(path)
         else:
           reads[path] = repo_zip.Read(path)
       return reads
-    return Future(callback=resolve)
+    return self._repo_zip.Then(read)
 
   def Stat(self, path):
     '''Stats |path| returning its version as as StatInfo object. If |path| ends
     with a '/', it is assumed to be a directory and the StatInfo object returned
     includes child_versions for all paths in the directory.
 
     File paths do not include the name of the zip file, which is arbitrary and
     useless to consumers.
 
     Because the repository will only be downloaded once per server version, all
@@ skipping 16 matching lines @@
                                       for p in repo_zip.List(path))
     return stat_info
 
   def GetIdentity(self):
     return '%s' % StringIdentity(self.__class__.__name__ + self._repo_key)
 
   def __repr__(self):
     return '%s(key=%s, url=%s)' % (type(self).__name__,
                                    self._repo_key,
                                    self._repo_url)