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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <set>
#include <string>
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "base/prefs/persistent_pref_store.h"
// Provides a unified PersistentPrefStore implementation that splits its storage
// and retrieval between two underlying PersistentPrefStore instances: a set of
// preference names is used to partition the preferences.
// Combines properties of the two stores as follows:
// * The unified read error will be:
// Selected Store Error
// Default Store Error | NO_ERROR | NO_FILE | other selected |
// NO_ERROR | NO_ERROR | NO_ERROR | other selected |
// other default | other default | other default | other default |
// * The unified initialization success, initialization completion, and
// read-only state are the boolean OR of the underlying stores' properties.
class SegregatedPrefStore : public PersistentPrefStore {
// Creates an instance that delegates to |selected_pref_store| for the
// preferences named in |selected_pref_names| and to |default_pref_store|
// for all others. If an unselected preference is present in
// |selected_pref_store| (i.e. because it was previously selected) it will
// be migrated back to |default_pref_store| upon access via a non-const
// method.
// |on_initialization| will be invoked when both stores have been initialized,
// before observers of the SegregatedPrefStore store are notified.
const scoped_refptr<PersistentPrefStore>& default_pref_store,
const scoped_refptr<PersistentPrefStore>& selected_pref_store,
const std::set<std::string>& selected_pref_names);
// PrefStore implementation
virtual void AddObserver(Observer* observer) OVERRIDE;
virtual void RemoveObserver(Observer* observer) OVERRIDE;
virtual bool HasObservers() const OVERRIDE;
virtual bool IsInitializationComplete() const OVERRIDE;
virtual bool GetValue(const std::string& key,
const base::Value** result) const OVERRIDE;
// WriteablePrefStore implementation
virtual void SetValue(const std::string& key, base::Value* value) OVERRIDE;
virtual void RemoveValue(const std::string& key) OVERRIDE;
// PersistentPrefStore implementation
virtual bool GetMutableValue(const std::string& key,
base::Value** result) OVERRIDE;
virtual void ReportValueChanged(const std::string& key) OVERRIDE;
virtual void SetValueSilently(const std::string& key,
base::Value* value) OVERRIDE;
virtual bool ReadOnly() const OVERRIDE;
virtual PrefReadError GetReadError() const OVERRIDE;
virtual PrefReadError ReadPrefs() OVERRIDE;
virtual void ReadPrefsAsync(ReadErrorDelegate* error_delegate) OVERRIDE;
virtual void CommitPendingWrite() OVERRIDE;
// Aggregates events from the underlying stores and synthesizes external
// events via |on_initialization|, |read_error_delegate_|, and |observers_|.
class AggregatingObserver : public PrefStore::Observer {
explicit AggregatingObserver(SegregatedPrefStore* outer);
// PrefStore::Observer implementation
virtual void OnPrefValueChanged(const std::string& key) OVERRIDE;
virtual void OnInitializationCompleted(bool succeeded) OVERRIDE;
SegregatedPrefStore* outer_;
int failed_sub_initializations_;
int successful_sub_initializations_;
virtual ~SegregatedPrefStore();
// Returns |selected_pref_store| if |key| is selected and |default_pref_store|
// otherwise.
PersistentPrefStore* StoreForKey(const std::string& key);
const PersistentPrefStore* StoreForKey(const std::string& key) const;
scoped_refptr<PersistentPrefStore> default_pref_store_;
scoped_refptr<PersistentPrefStore> selected_pref_store_;
std::set<std::string> selected_preference_names_;
scoped_ptr<PersistentPrefStore::ReadErrorDelegate> read_error_delegate_;
ObserverList<PrefStore::Observer, true> observers_;
AggregatingObserver aggregating_observer_;