| // Copyright 2018 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. |
| |
| #ifndef BASE_OBSERVER_LIST_TYPES_H_ |
| #define BASE_OBSERVER_LIST_TYPES_H_ |
| |
| #include "base/base_export.h" |
| #include "base/macros.h" |
| #include "base/memory/weak_ptr.h" |
| |
| namespace base { |
| namespace internal { |
| class CheckedObserverAdapter; |
| } |
| |
| // A CheckedObserver serves as a base class for an observer interface designed |
| // to be used with base::ObserverList. It helps detect potential use-after-free |
| // issues that can occur when observers fail to remove themselves from an |
| // observer list upon destruction. |
| // |
| // A CheckedObserver will CHECK() if an ObserverList iteration is attempted over |
| // a destroyed Observer. |
| // |
| // Note that a CheckedObserver subclass must be deleted on the same thread as |
| // the ObserverList(s) it is added to. This is DCHECK()ed via WeakPtr. |
| class BASE_EXPORT CheckedObserver { |
| public: |
| CheckedObserver(); |
| |
| protected: |
| virtual ~CheckedObserver(); |
| |
| // Returns whether |this| is in any ObserverList. Subclasses can CHECK() this |
| // in their destructor to obtain a nicer stacktrace. |
| bool IsInObserverList() const; |
| |
| private: |
| friend class internal::CheckedObserverAdapter; |
| |
| // Must be mutable to allow ObserverList<const Foo>. |
| mutable WeakPtrFactory<CheckedObserver> factory_; |
| |
| DISALLOW_COPY_AND_ASSIGN(CheckedObserver); |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_OBSERVER_LIST_TYPES_H_ |