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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 #ifndef SYNC_SYNCABLE_SYNCABLE_CHANGES_VERSION_H_ | 5 #ifndef COMPONENTS_SYNC_SYNCABLE_SYNCABLE_CHANGES_VERSION_H_ |
| 6 #define SYNC_SYNCABLE_SYNCABLE_CHANGES_VERSION_H_ | 6 #define COMPONENTS_SYNC_SYNCABLE_SYNCABLE_CHANGES_VERSION_H_ |
| 7 | 7 |
| 8 namespace syncer { | 8 namespace syncer { |
| 9 namespace syncable { | 9 namespace syncable { |
| 10 | 10 |
| 11 // For the most part, the sync engine treats version numbers as opaque values. | 11 // For the most part, the sync engine treats version numbers as opaque values. |
| 12 // However, there are parts of our code base that break this abstraction, and | 12 // However, there are parts of our code base that break this abstraction, and |
| 13 // depend on the following two invariants: | 13 // depend on the following two invariants: |
| 14 // | 14 // |
| 15 // 1. CHANGES_VERSION is less than 0. | 15 // 1. CHANGES_VERSION is less than 0. |
| 16 // 2. The server only issues positive version numbers. | 16 // 2. The server only issues positive version numbers. |
| 17 // | 17 // |
| 18 // Breaking these abstractions makes some operations 10 times | 18 // Breaking these abstractions makes some operations 10 times |
| 19 // faster. If either of these invariants change, then those queries | 19 // faster. If either of these invariants change, then those queries |
| 20 // must be revisited. | 20 // must be revisited. |
| 21 | 21 |
| 22 enum { | 22 enum { CHANGES_VERSION = -1 }; |
| 23 CHANGES_VERSION = -1 | |
| 24 }; | |
| 25 | 23 |
| 26 #define CHANGES_VERSION_STRING "-1" | 24 #define CHANGES_VERSION_STRING "-1" |
| 27 | 25 |
| 28 } // namespace syncable | 26 } // namespace syncable |
| 29 } // namespace syncer | 27 } // namespace syncer |
| 30 | 28 |
| 31 #endif // SYNC_SYNCABLE_SYNCABLE_CHANGES_VERSION_H_ | 29 #endif // COMPONENTS_SYNC_SYNCABLE_SYNCABLE_CHANGES_VERSION_H_ |
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