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   virtual ~PrefModelAssociator();
  42
  43   // See description above field for details.
  44   bool models_associated() const { return models_associated_; }
  45
  46   // syncer::SyncableService implementation.
  47   virtual syncer::SyncDataList GetAllSyncData(
  48       syncer::ModelType type) const OVERRIDE;
  49   virtual syncer::SyncError ProcessSyncChanges(
  50       const tracked_objects::Location& from_here,
  51       const syncer::SyncChangeList& change_list) OVERRIDE;
  52   virtual syncer::SyncMergeResult MergeDataAndStartSyncing(
  53       syncer::ModelType type,
  54       const syncer::SyncDataList& initial_sync_data,
  55       scoped_ptr<syncer::SyncChangeProcessor> sync_processor,
  56       scoped_ptr<syncer::SyncErrorFactory> sync_error_factory) OVERRIDE;
  57   virtual void StopSyncing(syncer::ModelType type) OVERRIDE;
  58
  59   // Returns the list of preference names that are registered as syncable, and
  60   // hence should be monitored for changes.
  61   std::set<std::string> registered_preferences() const;
  62
  63   // Register a preference with the specified name for syncing. We do not care
  64   // about the type at registration time, but when changes arrive from the
  65   // syncer, we check if they can be applied and if not drop them.
  66   // Note: This should only be called at profile startup time (before sync
  67   // begins).
  68   virtual void RegisterPref(const char* name);
  69
  70   // Returns true if the specified preference is registered for syncing.
  71   virtual bool IsPrefRegistered(const char* name);
  72
  73   // Process a local preference change. This can trigger new SyncChanges being
  74   // sent to the syncer.
  75   virtual void ProcessPrefChange(const std::string& name);
  76
  77   void SetPrefService(PrefServiceSyncable* pref_service);
  78
  79   // Merges the local_value into the supplied server_value and returns
  80   // the result (caller takes ownership). If there is a conflict, the server
  81   // value always takes precedence. Note that only certain preferences will
  82   // actually be merged, all others will return a copy of the server value. See
  83   // the method's implementation for details.
  84   static scoped_ptr<base::Value> MergePreference(
  85       const std::string& name,
  86       const base::Value& local_value,
  87       const base::Value& server_value);
  88
  89   // Fills |sync_data| with a sync representation of the preference data
  90   // provided.
  91   bool CreatePrefSyncData(const std::string& name,
  92                           const base::Value& value,
  93                           syncer::SyncData* sync_data) const;
  94
  95   // Extract preference value and name from sync specifics.
  96   base::Value* ReadPreferenceSpecifics(
  97       const sync_pb::PreferenceSpecifics& specifics,
  98       std::string* name);
  99
 100   // Returns true if the pref under the given name is pulled down from sync.
 101   // Note this does not refer to SYNCABLE_PREF.
 102   bool IsPrefSynced(const std::string& name) const;
 103
 104   // Adds a SyncedPrefObserver to watch for changes to a specific pref.
 105   void AddSyncedPrefObserver(const std::string& name,
 106                              SyncedPrefObserver* observer);
 107
 108   // Removes a SyncedPrefObserver from a pref's list of observers.
 109   void RemoveSyncedPrefObserver(const std::string& name,
 110                                 SyncedPrefObserver* observer);
 111
 112  protected:
 113   friend class PrefsSyncableServiceTest;
 114
 115   typedef std::map<std::string, syncer::SyncData> SyncDataMap;
 116
 117   // Create an association for a given preference. If |sync_pref| is valid,
 118   // signifying that sync has data for this preference, we reconcile their data
 119   // with ours and append a new UPDATE SyncChange to |sync_changes|. If
 120   // sync_pref is not set, we append an ADD SyncChange to |sync_changes| with
 121   // the current preference data.
 122   // |migrated_preference_list| points to a vector that may be updated with a
 123   // string containing the old name of the preference described by |pref_name|.
 124   // Note: We do not modify the sync data for preferences that are either
 125   // controlled by policy (are not user modifiable) or have their default value
 126   // (are not user controlled).
 127   void InitPrefAndAssociate(const syncer::SyncData& sync_pref,
 128                             const std::string& pref_name,
 129                             syncer::SyncChangeList* sync_changes,
 130                             SyncDataMap* migrated_preference_list);
 131
 132   static base::Value* MergeListValues(
 133       const base::Value& from_value, const base::Value& to_value);
 134   static base::Value* MergeDictionaryValues(const base::Value& from_value,
 135                                             const base::Value& to_value);
 136
 137   // Returns whether a given preference name is a new name of a migrated
 138   // preference. Exposed here for testing.
 139   static bool IsMigratedPreference(const char* preference_name);
 140   static bool IsOldMigratedPreference(const char* old_preference_name);
 141
 142   // Do we have an active association between the preferences and sync models?
 143   // Set when start syncing, reset in StopSyncing. While this is not set, we
 144   // ignore any local preference changes (when we start syncing we will look
 145   // up the most recent values anyways).
 146   bool models_associated_;
 147
 148   // Whether we're currently processing changes from the syncer. While this is
 149   // true, we ignore any local preference changes, since we triggered them.
 150   bool processing_syncer_changes_;
 151
 152   // A set of preference names.
 153   typedef std::set<std::string> PreferenceSet;
 154
 155   // All preferences that have registered as being syncable with this profile.
 156   PreferenceSet registered_preferences_;
 157
 158   // The preferences that are currently synced (excludes those preferences
 159   // that have never had sync data and currently have default values or are
 160   // policy controlled).
 161   // Note: this set never decreases, only grows to eventually match
 162   // registered_preferences_ as more preferences are synced. It determines
 163   // whether a preference change should update an existing sync node or create
 164   // a new sync node.
 165   PreferenceSet synced_preferences_;
 166
 167   // The PrefService we are syncing to.
 168   PrefServiceSyncable* pref_service_;
 169
 170   // Sync's syncer::SyncChange handler. We push all our changes through this.
 171   scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
 172
 173   // Sync's error handler. We use this to create sync errors.
 174   scoped_ptr<syncer::SyncErrorFactory> sync_error_factory_;
 175
 176   // The datatype that this associator is responible for, either PREFERENCES or
 177   // PRIORITY_PREFERENCES.
 178   syncer::ModelType type_;
 179
 180  private:
 181   // Map prefs to lists of observers. Observers will receive notification when
 182   // a pref changes, including the detail of whether or not the change came
 183   // from sync.
 184   typedef ObserverList<SyncedPrefObserver> SyncedPrefObserverList;
 185   typedef base::hash_map<std::string, SyncedPrefObserverList*>
 186       SyncedPrefObserverMap;
 187
 188   void NotifySyncedPrefObservers(const std::string& path, bool from_sync) const;
 189
 190   SyncedPrefObserverMap synced_pref_observers_;
 191
 192   DISALLOW_COPY_AND_ASSIGN(PrefModelAssociator);
 193 };
 194
 195 #endif  // CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_