base/prefs/pref_notifier_impl.h

   1 // Copyright (c) 2011 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 BASE_PREFS_PREF_NOTIFIER_IMPL_H_
   6 #define BASE_PREFS_PREF_NOTIFIER_IMPL_H_
   7
   8 #include <list>
   9 #include <string>
  10
  11 #include "base/callback.h"
  12 #include "base/compiler_specific.h"
  13 #include "base/containers/hash_tables.h"
  14 #include "base/observer_list.h"
  15 #include "base/prefs/base_prefs_export.h"
  16 #include "base/prefs/pref_notifier.h"
  17 #include "base/prefs/pref_observer.h"
  18 #include "base/threading/thread_checker.h"
  19
  20 class PrefService;
  21
  22 // The PrefNotifier implementation used by the PrefService.
  23 class BASE_PREFS_EXPORT PrefNotifierImpl
  24     : public NON_EXPORTED_BASE(PrefNotifier) {
  25  public:
  26   PrefNotifierImpl();
  27   explicit PrefNotifierImpl(PrefService* pref_service);
  28   ~PrefNotifierImpl() override;
  29
  30   // If the pref at the given path changes, we call the observer's
  31   // OnPreferenceChanged method.
  32   void AddPrefObserver(const std::string& path, PrefObserver* observer);
  33   void RemovePrefObserver(const std::string& path, PrefObserver* observer);
  34
  35   // We run the callback once, when initialization completes. The bool
  36   // parameter will be set to true for successful initialization,
  37   // false for unsuccessful.
  38   void AddInitObserver(base::Callback<void(bool)> observer);
  39
  40   void SetPrefService(PrefService* pref_service);
  41
  42  protected:
  43   // PrefNotifier overrides.
  44   void OnPreferenceChanged(const std::string& pref_name) override;
  45   void OnInitializationCompleted(bool succeeded) override;
  46
  47   // A map from pref names to a list of observers. Observers get fired in the
  48   // order they are added. These should only be accessed externally for unit
  49   // testing.
  50   typedef base::ObserverList<PrefObserver> PrefObserverList;
  51   typedef base::hash_map<std::string, PrefObserverList*> PrefObserverMap;
  52
  53   typedef std::list<base::Callback<void(bool)>> PrefInitObserverList;
  54
  55   const PrefObserverMap* pref_observers() const { return &pref_observers_; }
  56
  57  private:
  58   // For the given pref_name, fire any observer of the pref. Virtual so it can
  59   // be mocked for unit testing.
  60   virtual void FireObservers(const std::string& path);
  61
  62   // Weak reference; the notifier is owned by the PrefService.
  63   PrefService* pref_service_;
  64
  65   PrefObserverMap pref_observers_;
  66   PrefInitObserverList init_observers_;
  67
  68   base::ThreadChecker thread_checker_;
  69
  70   DISALLOW_COPY_AND_ASSIGN(PrefNotifierImpl);
  71 };
  72
  73 #endif  // BASE_PREFS_PREF_NOTIFIER_IMPL_H_