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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 #ifndef BASE_MEMORY_REF_COUNTED_H_ | 5 #ifndef BASE_MEMORY_REF_COUNTED_H_ |
6 #define BASE_MEMORY_REF_COUNTED_H_ | 6 #define BASE_MEMORY_REF_COUNTED_H_ |
7 | 7 |
8 #include <stddef.h> | 8 #include <stddef.h> |
9 | 9 |
10 #include <cassert> | 10 #include <cassert> |
11 #include <iosfwd> | 11 #include <iosfwd> |
12 #include <type_traits> | 12 #include <type_traits> |
13 | 13 |
14 #include "base/atomic_ref_count.h" | 14 #include "base/atomic_ref_count.h" |
15 #include "base/base_export.h" | 15 #include "base/base_export.h" |
16 #include "base/compiler_specific.h" | 16 #include "base/compiler_specific.h" |
17 #include "base/logging.h" | 17 #include "base/logging.h" |
18 #include "base/macros.h" | 18 #include "base/macros.h" |
19 #include "base/sequence_checker.h" | |
19 #include "base/threading/thread_collision_warner.h" | 20 #include "base/threading/thread_collision_warner.h" |
20 #include "build/build_config.h" | 21 #include "build/build_config.h" |
21 | 22 |
22 namespace base { | 23 namespace base { |
23 | |
24 namespace subtle { | 24 namespace subtle { |
25 | 25 |
26 class BASE_EXPORT RefCountedBase { | 26 class BASE_EXPORT RefCountedBase { |
27 public: | 27 public: |
28 bool HasOneRef() const { return ref_count_ == 1; } | 28 bool HasOneRef() const { return ref_count_ == 1; } |
29 | 29 |
30 protected: | 30 protected: |
31 RefCountedBase() | 31 RefCountedBase(); |
32 : ref_count_(0) | 32 ~RefCountedBase(); |
33 #if DCHECK_IS_ON() | |
34 , in_dtor_(false) | |
35 #endif | |
36 { | |
37 } | |
38 | |
39 ~RefCountedBase() { | |
40 #if DCHECK_IS_ON() | |
41 DCHECK(in_dtor_) << "RefCounted object deleted without calling Release()"; | |
42 #endif | |
43 } | |
44 | |
45 | 33 |
46 void AddRef() const { | 34 void AddRef() const { |
35 ++ref_count_; | |
36 | |
47 // TODO(maruel): Add back once it doesn't assert 500 times/sec. | 37 // TODO(maruel): Add back once it doesn't assert 500 times/sec. |
48 // Current thread books the critical section "AddRelease" | 38 // Current thread books the critical section "AddRelease" |
49 // without release it. | 39 // without release it. |
50 // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_); | 40 // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_); |
51 #if DCHECK_IS_ON() | 41 #if DCHECK_IS_ON() |
52 DCHECK(!in_dtor_); | 42 DCHECK(!in_dtor_); |
43 if (ref_count_ >= 2) | |
44 DCHECK(CalledOnValidSequence()); | |
gab
2017/02/16 21:38:47
I found this whole comparing with "2" confusing (t
tzik
2017/02/17 11:36:08
Done.
| |
53 #endif | 45 #endif |
54 ++ref_count_; | |
55 } | 46 } |
56 | 47 |
57 // Returns true if the object should self-delete. | 48 // Returns true if the object should self-delete. |
58 bool Release() const { | 49 bool Release() const { |
59 // TODO(maruel): Add back once it doesn't assert 500 times/sec. | 50 // TODO(maruel): Add back once it doesn't assert 500 times/sec. |
60 // Current thread books the critical section "AddRelease" | 51 // Current thread books the critical section "AddRelease" |
61 // without release it. | 52 // without release it. |
62 // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_); | 53 // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_); |
63 #if DCHECK_IS_ON() | 54 #if DCHECK_IS_ON() |
64 DCHECK(!in_dtor_); | 55 DCHECK(!in_dtor_); |
56 if (ref_count_ >= 2) | |
57 DCHECK(CalledOnValidSequence()); | |
58 if (ref_count_ == 2) | |
59 DetachFromSequence(); | |
65 #endif | 60 #endif |
66 if (--ref_count_ == 0) { | 61 if (--ref_count_ == 0) { |
67 #if DCHECK_IS_ON() | 62 #if DCHECK_IS_ON() |
68 in_dtor_ = true; | 63 in_dtor_ = true; |
69 #endif | 64 #endif |
70 return true; | 65 return true; |
71 } | 66 } |
72 return false; | 67 return false; |
73 } | 68 } |
74 | 69 |
75 private: | 70 private: |
71 void DetachFromSequence() const; | |
gab
2017/02/16 21:38:46
Invoked sequence_checker_.DetachFromSequence() dir
tzik
2017/02/17 11:36:08
Done.
| |
72 bool CalledOnValidSequence() const; | |
gab
2017/02/16 21:38:47
Wrap method itself in DCHECK_IS_ON() since it's al
tzik
2017/02/17 11:36:08
Done.
| |
73 | |
76 mutable size_t ref_count_; | 74 mutable size_t ref_count_; |
gab
2017/02/16 21:38:47
Tangential cleanup while you're here
= 0;
here a
tzik
2017/02/17 11:36:09
Done.
| |
77 #if DCHECK_IS_ON() | 75 #if DCHECK_IS_ON() |
78 mutable bool in_dtor_; | 76 mutable bool in_dtor_ = false; |
77 mutable SequenceChecker sequence_checker_; | |
79 #endif | 78 #endif |
80 | 79 |
81 DFAKE_MUTEX(add_release_); | 80 DFAKE_MUTEX(add_release_); |
82 | 81 |
83 DISALLOW_COPY_AND_ASSIGN(RefCountedBase); | 82 DISALLOW_COPY_AND_ASSIGN(RefCountedBase); |
84 }; | 83 }; |
85 | 84 |
86 class BASE_EXPORT RefCountedThreadSafeBase { | 85 class BASE_EXPORT RefCountedThreadSafeBase { |
87 public: | 86 public: |
88 bool HasOneRef() const; | 87 bool HasOneRef() const; |
(...skipping 11 matching lines...) Expand all Loading... | |
100 mutable AtomicRefCount ref_count_; | 99 mutable AtomicRefCount ref_count_; |
101 #if DCHECK_IS_ON() | 100 #if DCHECK_IS_ON() |
102 mutable bool in_dtor_; | 101 mutable bool in_dtor_; |
103 #endif | 102 #endif |
104 | 103 |
105 DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafeBase); | 104 DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafeBase); |
106 }; | 105 }; |
107 | 106 |
108 } // namespace subtle | 107 } // namespace subtle |
109 | 108 |
109 class BASE_EXPORT ScopedAllowCrossThreadRefCountAccess final { | |
gab
2017/02/16 21:38:46
// See RefCounted class for documentation.
tzik
2017/02/17 11:36:08
Done.
| |
110 public: | |
111 #if DCHECK_IS_ON() | |
112 ScopedAllowCrossThreadRefCountAccess(); | |
113 ~ScopedAllowCrossThreadRefCountAccess(); | |
114 #else | |
115 ScopedAllowCrossThreadRefCountAccess() {} | |
116 ~ScopedAllowCrossThreadRefCountAccess() {} | |
117 #endif | |
118 }; | |
119 | |
110 // | 120 // |
111 // A base class for reference counted classes. Otherwise, known as a cheap | 121 // A base class for reference counted classes. Otherwise, known as a cheap |
112 // knock-off of WebKit's RefCounted<T> class. To use this, just extend your | 122 // knock-off of WebKit's RefCounted<T> class. To use this, just extend your |
113 // class from it like so: | 123 // class from it like so: |
114 // | 124 // |
115 // class MyFoo : public base::RefCounted<MyFoo> { | 125 // class MyFoo : public base::RefCounted<MyFoo> { |
116 // ... | 126 // ... |
117 // private: | 127 // private: |
118 // friend class base::RefCounted<MyFoo>; | 128 // friend class base::RefCounted<MyFoo>; |
119 // ~MyFoo(); | 129 // ~MyFoo(); |
120 // }; | 130 // }; |
121 // | 131 // |
122 // You should always make your destructor non-public, to avoid any code deleting | 132 // You should always make your destructor non-public, to avoid any code deleting |
123 // the object accidently while there are references to it. | 133 // the object accidently while there are references to it. |
134 // | |
135 // The ref count manipulation to RefCounted is NOT thread safe, and has DCHECKs | |
gab
2017/02/16 21:38:47
rm comma
tzik
2017/02/17 11:36:08
Done.
| |
136 // to trap unsafe cross thread usages. A subclass instance of RefCounted can be | |
gab
2017/02/16 21:38:47
s/usages/usage/
tzik
2017/02/17 11:36:08
Done.
| |
137 // passed to the other thread or sequence only when its ref count is 1. If the | |
138 // ref count is more than 1, the ref count checks if it's on the same thread or | |
gab
2017/02/16 21:38:47
s/checks if it's on the same thread or sequence to
tzik
2017/02/17 11:36:09
Done.
| |
139 // sequence to the previous ones. | |
gab
2017/02/16 21:38:47
s/thread or sequence/execution sequence/
tzik
2017/02/17 11:36:08
Done.
| |
140 // If you want to temporarily opt-out from the check, use | |
141 // ScopedAllowCrossThreadRefCountAccess to disable the DCHECK. | |
gab
2017/02/16 21:38:47
For this last paragraph:
// In rare cases where
tzik
2017/02/17 11:36:09
Done.
| |
124 template <class T> | 142 template <class T> |
125 class RefCounted : public subtle::RefCountedBase { | 143 class RefCounted : public subtle::RefCountedBase { |
126 public: | 144 public: |
127 RefCounted() = default; | 145 RefCounted() = default; |
128 | 146 |
129 void AddRef() const { | 147 void AddRef() const { |
130 subtle::RefCountedBase::AddRef(); | 148 subtle::RefCountedBase::AddRef(); |
131 } | 149 } |
132 | 150 |
133 void Release() const { | 151 void Release() const { |
(...skipping 321 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... | |
455 bool operator!=(std::nullptr_t null, const scoped_refptr<T>& rhs) { | 473 bool operator!=(std::nullptr_t null, const scoped_refptr<T>& rhs) { |
456 return !operator==(null, rhs); | 474 return !operator==(null, rhs); |
457 } | 475 } |
458 | 476 |
459 template <typename T> | 477 template <typename T> |
460 std::ostream& operator<<(std::ostream& out, const scoped_refptr<T>& p) { | 478 std::ostream& operator<<(std::ostream& out, const scoped_refptr<T>& p) { |
461 return out << p.get(); | 479 return out << p.get(); |
462 } | 480 } |
463 | 481 |
464 #endif // BASE_MEMORY_REF_COUNTED_H_ | 482 #endif // BASE_MEMORY_REF_COUNTED_H_ |
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