sync/engine/conflict_resolver.h

   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 //
   5 // A class that watches the syncer and attempts to resolve any conflicts that
   6 // occur.
   7
   8 #ifndef SYNC_ENGINE_CONFLICT_RESOLVER_H_
   9 #define SYNC_ENGINE_CONFLICT_RESOLVER_H_
  10
  11 #include <set>
  12
  13 #include "base/basictypes.h"
  14 #include "base/gtest_prod_util.h"
  15 #include "sync/engine/syncer_types.h"
  16
  17 namespace syncer {
  18
  19 namespace syncable {
  20 class Id;
  21 class WriteTransaction;
  22 }  // namespace syncable
  23
  24 class Cryptographer;
  25 struct UpdateCounters;
  26
  27 namespace sessions {
  28 class StatusController;
  29 }  // namespace sessions
  30
  31 class ConflictResolver {
  32   friend class SyncerTest;
  33   FRIEND_TEST_ALL_PREFIXES(SyncerTest,
  34                            ConflictResolverMergeOverwritesLocalEntry);
  35  public:
  36   // Enumeration of different conflict resolutions. Used for histogramming.
  37   enum SimpleConflictResolutions {
  38     OVERWRITE_LOCAL,           // Resolved by overwriting local changes.
  39     OVERWRITE_SERVER,          // Resolved by overwriting server changes.
  40     UNDELETE,                  // Resolved by undeleting local item.
  41     IGNORE_ENCRYPTION,         // Resolved by ignoring an encryption-only server
  42                                // change.
  43     NIGORI_MERGE,              // Resolved by merging nigori nodes.
  44     CHANGES_MATCH,             // Resolved by ignoring both local and server
  45                                // changes because they matched.
  46     CONFLICT_RESOLUTION_SIZE,
  47   };
  48
  49   ConflictResolver();
  50   ~ConflictResolver();
  51   // Called by the syncer at the end of a update/commit cycle.
  52   // Returns true if the syncer should try to apply its updates again.
  53   void ResolveConflicts(syncable::WriteTransaction* trans,
  54                         const Cryptographer* cryptographer,
  55                         const std::set<syncable::Id>& simple_conflict_ids,
  56                         sessions::StatusController* status,
  57                         UpdateCounters* counters);
  58
  59  private:
  60   void ProcessSimpleConflict(
  61       syncable::WriteTransaction* trans,
  62       const syncable::Id& id,
  63       const Cryptographer* cryptographer,
  64       sessions::StatusController* status,
  65       UpdateCounters* counters);
  66
  67   DISALLOW_COPY_AND_ASSIGN(ConflictResolver);
  68 };
  69
  70 }  // namespace syncer
  71
  72 #endif  // SYNC_ENGINE_CONFLICT_RESOLVER_H_