Extensions Docs Server: Efficient MemcacheFileSystem

chrome/common/extensions/docs/server2/memcache_file_system.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.
 
 from file_system import FileSystem
 from future import Future
 import appengine_memcache as memcache
 
 class MemcacheFileSystem(FileSystem):
   """FileSystem implementation which memcaches the results of Read.
   """
   def __init__(self, file_system, memcache):
     self._file_system = file_system
     self._memcache = memcache
 
   def Stat(self, path):
     """Stats the directory given, or if a file is given, the file's parent
     directory.
     """
     version = self._memcache.Get(path, memcache.MEMCACHE_FILE_SYSTEM_STAT)
     if version is None:
       stat_info = self._file_system.Stat(path)
-      self._memcache.Set(path,
+      self._memcache.Set(path.rsplit('/', 1)[0] + '/',
                          stat_info.version,
                          memcache.MEMCACHE_FILE_SYSTEM_STAT)
+      for child_path, child_version in stat_info.child_versions.iteritems():
+        self._memcache.Set(path.rsplit('/', 1)[0] + '/' + child_path,
+                           child_version,
+                           memcache.MEMCACHE_FILE_SYSTEM_STAT)
     else:
-      stat_info = self.StatInfo(version)
+      stat_info = self.StatInfo(version, {})
     return stat_info
 
   def Read(self, paths, binary=False):
     """Reads a list of files. If a file is in memcache and it is not out of
     date, it is returned. Otherwise, the file is retrieved from the file system.
     """
     result = {}
     uncached = []
     for path in paths:
       cached_result = self._memcache.Get(path,
                                          memcache.MEMCACHE_FILE_SYSTEM_READ)
       if cached_result is None:
         uncached.append(path)
         continue
       data, version = cached_result
       if self.Stat(path).version > version:
         self._memcache.Delete(path, memcache.MEMCACHE_FILE_SYSTEM_READ)
         uncached.append(path)
         continue
       result[path] = data
     new_items = self._file_system.Read(uncached, binary=binary).Get()
     for item in new_items:
       version = self.Stat(item).version
       value = new_items[item]
       self._memcache.Set(item,
                          (value, version),
                          memcache.MEMCACHE_FILE_SYSTEM_READ)
       result[item] = value
     return Future(value=result)