net/disk_cache/simple/simple_backend_version.h

   1 // Copyright 2013 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
   5 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_VERSION_H_
   6 #define NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_VERSION_H_
   7
   8 namespace disk_cache {
   9
  10 // Short rules helping to think about data upgrades within Simple Cache:
  11 //   * ALL changes of on-disk data format, backward-compatible or not,
  12 //     forward-compatible or not, require updating the |kSimpleVersion|.
  13 //   * All cache Upgrades are performed on backend start, must be finished
  14 //     before the new backend starts processing any incoming operations.
  15 //   * If the Upgrade is not implemented for transition from
  16 //     |kSimpleVersion - 1| then the whole cache directory will be cleared.
  17 //   * Dropping cache data on disk or some of its parts can be a valid way to
  18 //     Upgrade.
  19 const uint32 kSimpleVersion = 6;
  20
  21 // The version of the entry file(s) as written to disk. Must be updated iff the
  22 // entry format changes with the overall backend version update.
  23 const uint32 kSimpleEntryVersionOnDisk = 5;
  24
  25 }  // namespace disk_cache
  26
  27 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_VERSION_H_