chrome/browser/prefs/pref_model_associator.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 #ifndef CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_
   6 #define CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11
  12 #include "base/basictypes.h"
  13 #include "base/compiler_specific.h"
  14 #include "base/containers/hash_tables.h"
  15 #include "base/gtest_prod_util.h"
  16 #include "base/observer_list.h"
  17 #include "base/threading/non_thread_safe.h"
  18 #include "chrome/browser/prefs/synced_pref_observer.h"
  19 #include "sync/api/sync_data.h"
  20 #include "sync/api/syncable_service.h"
  21
  22 class PrefRegistrySyncable;
  23 class PrefServiceSyncable;
  24
  25 namespace sync_pb {
  26 class PreferenceSpecifics;
  27 }
  28
  29 namespace base {
  30 class Value;
  31 }
  32
  33 // Contains all preference sync related logic.
  34 // TODO(sync): Merge this into PrefService once we separate the profile
  35 // PrefService from the local state PrefService.
  36 class PrefModelAssociator
  37     : public syncer::SyncableService,
  38       public base::NonThreadSafe {
  39  public:
  40   explicit PrefModelAssociator(syncer::ModelType type);
  41   ~PrefModelAssociator() override;
  42
  43   // See description above field for details.
  44   bool models_associated() const { return models_associated_; }
  45
  46   // syncer::SyncableService implementation.
  47   syncer::SyncDataList GetAllSyncData(syncer::ModelType type) const override;
  48   syncer::SyncError ProcessSyncChanges(
  49       const tracked_objects::Location& from_here,
  50       const syncer::SyncChangeList& change_list) override;
  51   syncer::SyncMergeResult MergeDataAndStartSyncing(
  52       syncer::ModelType type,
  53       const syncer::SyncDataList& initial_sync_data,
  54       scoped_ptr<syncer::SyncChangeProcessor> sync_processor,
  55       scoped_ptr<syncer::SyncErrorFactory> sync_error_factory) override;
  56   void StopSyncing(syncer::ModelType type) override;
  57
  58   // Returns the list of preference names that are registered as syncable, and
  59   // hence should be monitored for changes.
  60   std::set<std::string> registered_preferences() const;
  61
  62   // Register a preference with the specified name for syncing. We do not care
  63   // about the type at registration time, but when changes arrive from the
  64   // syncer, we check if they can be applied and if not drop them.
  65   // Note: This should only be called at profile startup time (before sync
  66   // begins).
  67   virtual void RegisterPref(const char* name);
  68
  69   // Returns true if the specified preference is registered for syncing.
  70   virtual bool IsPrefRegistered(const char* name);
  71
  72   // Process a local preference change. This can trigger new SyncChanges being
  73   // sent to the syncer.
  74   virtual void ProcessPrefChange(const std::string& name);
  75
  76   void SetPrefService(PrefServiceSyncable* pref_service);
  77
  78   // Merges the local_value into the supplied server_value and returns
  79   // the result (caller takes ownership). If there is a conflict, the server
  80   // value always takes precedence. Note that only certain preferences will
  81   // actually be merged, all others will return a copy of the server value. See
  82   // the method's implementation for details.
  83   static scoped_ptr<base::Value> MergePreference(
  84       const std::string& name,
  85       const base::Value& local_value,
  86       const base::Value& server_value);
  87
  88   // Fills |sync_data| with a sync representation of the preference data
  89   // provided.
  90   bool CreatePrefSyncData(const std::string& name,
  91                           const base::Value& value,
  92                           syncer::SyncData* sync_data) const;
  93
  94   // Extract preference value from sync specifics.
  95   base::Value* ReadPreferenceSpecifics(
  96       const sync_pb::PreferenceSpecifics& specifics);
  97
  98   // Returns true if the pref under the given name is pulled down from sync.
  99   // Note this does not refer to SYNCABLE_PREF.
 100   bool IsPrefSynced(const std::string& name) const;
 101
 102   // Adds a SyncedPrefObserver to watch for changes to a specific pref.
 103   void AddSyncedPrefObserver(const std::string& name,
 104                              SyncedPrefObserver* observer);
 105
 106   // Removes a SyncedPrefObserver from a pref's list of observers.
 107   void RemoveSyncedPrefObserver(const std::string& name,
 108                                 SyncedPrefObserver* observer);
 109
 110  protected:
 111   friend class PrefsSyncableServiceTest;
 112
 113   typedef std::map<std::string, syncer::SyncData> SyncDataMap;
 114
 115   // Create an association for a given preference. If |sync_pref| is valid,
 116   // signifying that sync has data for this preference, we reconcile their data
 117   // with ours and append a new UPDATE SyncChange to |sync_changes|. If
 118   // sync_pref is not set, we append an ADD SyncChange to |sync_changes| with
 119   // the current preference data.
 120   // |migrated_preference_list| points to a vector that may be updated with a
 121   // string containing the old name of the preference described by |pref_name|.
 122   // Note: We do not modify the sync data for preferences that are either
 123   // controlled by policy (are not user modifiable) or have their default value
 124   // (are not user controlled).
 125   void InitPrefAndAssociate(const syncer::SyncData& sync_pref,
 126                             const std::string& pref_name,
 127                             syncer::SyncChangeList* sync_changes,
 128                             SyncDataMap* migrated_preference_list);
 129
 130   static base::Value* MergeListValues(
 131       const base::Value& from_value, const base::Value& to_value);
 132   static base::Value* MergeDictionaryValues(const base::Value& from_value,
 133                                             const base::Value& to_value);
 134
 135   // Returns whether a given preference name is a new name of a migrated
 136   // preference. Exposed here for testing.
 137   static bool IsMigratedPreference(const char* preference_name);
 138   static bool IsOldMigratedPreference(const char* old_preference_name);
 139
 140   // Do we have an active association between the preferences and sync models?
 141   // Set when start syncing, reset in StopSyncing. While this is not set, we
 142   // ignore any local preference changes (when we start syncing we will look
 143   // up the most recent values anyways).
 144   bool models_associated_;
 145
 146   // Whether we're currently processing changes from the syncer. While this is
 147   // true, we ignore any local preference changes, since we triggered them.
 148   bool processing_syncer_changes_;
 149
 150   // A set of preference names.
 151   typedef std::set<std::string> PreferenceSet;
 152
 153   // All preferences that have registered as being syncable with this profile.
 154   PreferenceSet registered_preferences_;
 155
 156   // The preferences that are currently synced (excludes those preferences
 157   // that have never had sync data and currently have default values or are
 158   // policy controlled).
 159   // Note: this set never decreases, only grows to eventually match
 160   // registered_preferences_ as more preferences are synced. It determines
 161   // whether a preference change should update an existing sync node or create
 162   // a new sync node.
 163   PreferenceSet synced_preferences_;
 164
 165   // The PrefService we are syncing to.
 166   PrefServiceSyncable* pref_service_;
 167
 168   // Sync's syncer::SyncChange handler. We push all our changes through this.
 169   scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
 170
 171   // Sync's error handler. We use this to create sync errors.
 172   scoped_ptr<syncer::SyncErrorFactory> sync_error_factory_;
 173
 174   // The datatype that this associator is responible for, either PREFERENCES or
 175   // PRIORITY_PREFERENCES.
 176   syncer::ModelType type_;
 177
 178  private:
 179   // Map prefs to lists of observers. Observers will receive notification when
 180   // a pref changes, including the detail of whether or not the change came
 181   // from sync.
 182   typedef base::ObserverList<SyncedPrefObserver> SyncedPrefObserverList;
 183   typedef base::hash_map<std::string, SyncedPrefObserverList*>
 184       SyncedPrefObserverMap;
 185
 186   void NotifySyncedPrefObservers(const std::string& path, bool from_sync) const;
 187
 188   SyncedPrefObserverMap synced_pref_observers_;
 189
 190   DISALLOW_COPY_AND_ASSIGN(PrefModelAssociator);
 191 };
 192
 193 #endif  // CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_