object_store.py revision ca12bfac764ba476d6cd062bf1dde12cc64c3f40 
1# Copyright (c) 2012 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5from future import Future
6
7class _SingleGetFuture(object):
8  def __init__(self, multi_get, key):
9    self._future = multi_get
10    self._key = key
11
12  def Get(self):
13    return self._future.Get().get(self._key)
14
15class ObjectStore(object):
16  '''A class for caching picklable objects.
17  '''
18  def Get(self, key):
19    '''Gets a |Future| with the value of |key| in the object store, or None
20    if |key| is not in the object store.
21    '''
22    return Future(delegate=_SingleGetFuture(self.GetMulti([key]), key))
23
24  def GetMulti(self, keys):
25    '''Gets a |Future| with values mapped to |keys| from the object store, with
26    any keys not in the object store omitted.
27    '''
28    raise NotImplementedError(self.__class__)
29
30  def Set(self, key, value):
31    '''Sets key -> value in the object store.
32    '''
33    self.SetMulti({ key: value })
34
35  def SetMulti(self, items):
36    '''Atomically sets the mapping of keys to values in the object store.
37    '''
38    raise NotImplementedError(self.__class__)
39
40  def Del(self, key):
41    '''Deletes a key from the object store.
42    '''
43    self.DelMulti([key])
44
45  def DelMulti(self, keys):
46    '''Deletes |keys| from the object store.
47    '''
48    raise NotImplementedError(self.__class__)
49