content/browser/notification_service_impl.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 CONTENT_BROWSER_NOTIFICATION_SERVICE_IMPL_H_
   6 #define CONTENT_BROWSER_NOTIFICATION_SERVICE_IMPL_H_
   7
   8 #include <map>
   9
  10 #include "base/observer_list.h"
  11 #include "content/common/content_export.h"
  12 #include "content/public/browser/notification_service.h"
  13
  14 namespace content {
  15
  16 class NotificationObserver;
  17 class NotificationRegistrar;
  18
  19 class CONTENT_EXPORT NotificationServiceImpl : public NotificationService {
  20  public:
  21   static NotificationServiceImpl* current();
  22
  23   // Normally instantiated when the thread is created.  Not all threads have
  24   // a NotificationService.  Only one instance should be created per thread.
  25   NotificationServiceImpl();
  26   ~NotificationServiceImpl() override;
  27
  28   // NotificationService:
  29   void Notify(int type,
  30               const NotificationSource& source,
  31               const NotificationDetails& details) override;
  32
  33  private:
  34   friend class NotificationRegistrar;
  35
  36   typedef base::ObserverList<NotificationObserver> NotificationObserverList;
  37   typedef std::map<uintptr_t, NotificationObserverList*> NotificationSourceMap;
  38   typedef std::map<int, NotificationSourceMap> NotificationObserverMap;
  39   typedef std::map<int, int> NotificationObserverCount;
  40
  41   // Convenience function to determine whether a source has a
  42   // NotificationObserverList in the given map;
  43   static bool HasKey(const NotificationSourceMap& map,
  44                      const NotificationSource& source);
  45
  46   // NOTE: Rather than using this directly, you should use a
  47   // NotificationRegistrar.
  48   //
  49   // Registers a NotificationObserver to be called whenever a matching
  50   // notification is posted.  Observer is a pointer to an object subclassing
  51   // NotificationObserver to be notified when an event matching the other two
  52   // parameters is posted to this service.  Type is the type of events to be
  53   // notified about (or NOTIFICATION_ALL to receive events of all
  54   // types).
  55   // Source is a NotificationSource object (created using
  56   // "Source<classname>(pointer)"), if this observer only wants to
  57   // receive events from that object, or NotificationService::AllSources()
  58   // to receive events from all sources.
  59   //
  60   // A given observer can be registered only once for each combination of
  61   // type and source.  If the same object is registered more than once,
  62   // it must be removed for each of those combinations of type and source later.
  63   //
  64   // The caller retains ownership of the object pointed to by observer.
  65   void AddObserver(NotificationObserver* observer,
  66                    int type,
  67                    const NotificationSource& source);
  68
  69   // NOTE: Rather than using this directly, you should use a
  70   // NotificationRegistrar.
  71   //
  72   // Removes the object pointed to by observer from receiving notifications
  73   // that match type and source.  If no object matching the parameters is
  74   // currently registered, this method is a no-op.
  75   void RemoveObserver(NotificationObserver* observer,
  76                       int type,
  77                       const NotificationSource& source);
  78
  79   // Keeps track of the observers for each type of notification.
  80   // Until we get a prohibitively large number of notification types,
  81   // a simple array is probably the fastest way to dispatch.
  82   NotificationObserverMap observers_;
  83
  84 #ifndef NDEBUG
  85   // Used to check to see that AddObserver and RemoveObserver calls are
  86   // balanced.
  87   NotificationObserverCount observer_counts_;
  88 #endif
  89
  90   DISALLOW_COPY_AND_ASSIGN(NotificationServiceImpl);
  91 };
  92
  93 }  // namespace content
  94
  95 #endif  // CONTENT_BROWSER_NOTIFICATION_SERVICE_IMPL_H_