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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 // This file contains utility functions and classes that help the | 5 // This file contains utility functions and classes that help the |
6 // implementation, and management of the Callback objects. | 6 // implementation, and management of the Callback objects. |
7 | 7 |
8 #ifndef BASE_CALLBACK_INTERNAL_H_ | 8 #ifndef BASE_CALLBACK_INTERNAL_H_ |
9 #define BASE_CALLBACK_INTERNAL_H_ | 9 #define BASE_CALLBACK_INTERNAL_H_ |
10 | 10 |
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29 // RefCountedThreadSafe since it requires the destructor to be a virtual method. | 29 // RefCountedThreadSafe since it requires the destructor to be a virtual method. |
30 // Creating a vtable for every BindState template instantiation results in a lot | 30 // Creating a vtable for every BindState template instantiation results in a lot |
31 // of bloat. Its only task is to call the destructor which can be done with a | 31 // of bloat. Its only task is to call the destructor which can be done with a |
32 // function pointer. | 32 // function pointer. |
33 class BASE_EXPORT BindStateBase { | 33 class BASE_EXPORT BindStateBase { |
34 public: | 34 public: |
35 using InvokeFuncStorage = void(*)(); | 35 using InvokeFuncStorage = void(*)(); |
36 | 36 |
37 protected: | 37 protected: |
38 BindStateBase(InvokeFuncStorage polymorphic_invoke, | 38 BindStateBase(InvokeFuncStorage polymorphic_invoke, |
39 void (*destructor)(BindStateBase*)); | 39 void (*destructor)(BindStateBase*), |
| 40 bool (*is_cancelled)(const BindStateBase*)); |
40 ~BindStateBase() = default; | 41 ~BindStateBase() = default; |
41 | 42 |
42 private: | 43 private: |
43 friend class scoped_refptr<BindStateBase>; | 44 friend class scoped_refptr<BindStateBase>; |
44 template <CopyMode copy_mode> | 45 template <CopyMode copy_mode> |
45 friend class CallbackBase; | 46 friend class CallbackBase; |
46 | 47 |
| 48 bool IsCancelled() const { |
| 49 return is_cancelled_(this); |
| 50 } |
| 51 |
47 void AddRef(); | 52 void AddRef(); |
48 void Release(); | 53 void Release(); |
49 | 54 |
50 // In C++, it is safe to cast function pointers to function pointers of | 55 // In C++, it is safe to cast function pointers to function pointers of |
51 // another type. It is not okay to use void*. We create a InvokeFuncStorage | 56 // another type. It is not okay to use void*. We create a InvokeFuncStorage |
52 // that that can store our function pointer, and then cast it back to | 57 // that that can store our function pointer, and then cast it back to |
53 // the original type on usage. | 58 // the original type on usage. |
54 InvokeFuncStorage polymorphic_invoke_; | 59 InvokeFuncStorage polymorphic_invoke_; |
55 | 60 |
56 AtomicRefCount ref_count_; | 61 AtomicRefCount ref_count_; |
57 | 62 |
58 // Pointer to a function that will properly destroy |this|. | 63 // Pointer to a function that will properly destroy |this|. |
59 void (*destructor_)(BindStateBase*); | 64 void (*destructor_)(BindStateBase*); |
| 65 bool (*is_cancelled_)(const BindStateBase*); |
60 | 66 |
61 DISALLOW_COPY_AND_ASSIGN(BindStateBase); | 67 DISALLOW_COPY_AND_ASSIGN(BindStateBase); |
62 }; | 68 }; |
63 | 69 |
64 // Holds the Callback methods that don't require specialization to reduce | 70 // Holds the Callback methods that don't require specialization to reduce |
65 // template bloat. | 71 // template bloat. |
66 // CallbackBase<MoveOnly> is a direct base class of MoveOnly callbacks, and | 72 // CallbackBase<MoveOnly> is a direct base class of MoveOnly callbacks, and |
67 // CallbackBase<Copyable> uses CallbackBase<MoveOnly> for its implementation. | 73 // CallbackBase<Copyable> uses CallbackBase<MoveOnly> for its implementation. |
68 template <> | 74 template <> |
69 class BASE_EXPORT CallbackBase<CopyMode::MoveOnly> { | 75 class BASE_EXPORT CallbackBase<CopyMode::MoveOnly> { |
70 public: | 76 public: |
71 CallbackBase(CallbackBase&& c); | 77 CallbackBase(CallbackBase&& c); |
72 CallbackBase& operator=(CallbackBase&& c); | 78 CallbackBase& operator=(CallbackBase&& c); |
73 | 79 |
74 // Returns true if Callback is null (doesn't refer to anything). | 80 // Returns true if Callback is null (doesn't refer to anything). |
75 bool is_null() const { return bind_state_.get() == NULL; } | 81 bool is_null() const { return bind_state_.get() == NULL; } |
76 explicit operator bool() const { return !is_null(); } | 82 explicit operator bool() const { return !is_null(); } |
77 | 83 |
| 84 // Returns true if the callback invocation will be nop due to an cancellation. |
| 85 // It's invalid to call this on uninitialized callback. |
| 86 bool IsCancelled() const; |
| 87 |
78 // Returns the Callback into an uninitialized state. | 88 // Returns the Callback into an uninitialized state. |
79 void Reset(); | 89 void Reset(); |
80 | 90 |
81 protected: | 91 protected: |
82 using InvokeFuncStorage = BindStateBase::InvokeFuncStorage; | 92 using InvokeFuncStorage = BindStateBase::InvokeFuncStorage; |
83 | 93 |
84 // Returns true if this callback equals |other|. |other| may be null. | 94 // Returns true if this callback equals |other|. |other| may be null. |
85 bool EqualsInternal(const CallbackBase& other) const; | 95 bool EqualsInternal(const CallbackBase& other) const; |
86 | 96 |
87 // Allow initializing of |bind_state_| via the constructor to avoid default | 97 // Allow initializing of |bind_state_| via the constructor to avoid default |
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115 ~CallbackBase() {} | 125 ~CallbackBase() {} |
116 }; | 126 }; |
117 | 127 |
118 extern template class CallbackBase<CopyMode::MoveOnly>; | 128 extern template class CallbackBase<CopyMode::MoveOnly>; |
119 extern template class CallbackBase<CopyMode::Copyable>; | 129 extern template class CallbackBase<CopyMode::Copyable>; |
120 | 130 |
121 } // namespace internal | 131 } // namespace internal |
122 } // namespace base | 132 } // namespace base |
123 | 133 |
124 #endif // BASE_CALLBACK_INTERNAL_H_ | 134 #endif // BASE_CALLBACK_INTERNAL_H_ |
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