OLD | NEW |
1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 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 | 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 #include "base/memory/weak_ptr.h" | 5 #include "base/memory/weak_ptr.h" |
6 | 6 |
7 namespace base { | 7 namespace base { |
8 namespace internal { | 8 namespace internal { |
9 | 9 |
10 WeakReference::Flag::Flag() : is_valid_(true) { | 10 static constexpr uintptr_t kTrueMask = ~static_cast<uintptr_t>(0); |
| 11 |
| 12 WeakReference::Flag::Flag() : is_valid_(kTrueMask) { |
| 13 #if DCHECK_IS_ON() |
11 // Flags only become bound when checked for validity, or invalidated, | 14 // Flags only become bound when checked for validity, or invalidated, |
12 // so that we can check that later validity/invalidation operations on | 15 // so that we can check that later validity/invalidation operations on |
13 // the same Flag take place on the same sequenced thread. | 16 // the same Flag take place on the same sequenced thread. |
14 sequence_checker_.DetachFromSequence(); | 17 sequence_checker_.DetachFromSequence(); |
| 18 #endif |
15 } | 19 } |
16 | 20 |
17 void WeakReference::Flag::Invalidate() { | 21 WeakReference::Flag::Flag(WeakReference::Flag::NullFlagTag) : is_valid_(false) { |
18 // The flag being invalidated with a single ref implies that there are no | 22 // There is no need for sequence_checker_.DetachFromSequence() because the |
19 // weak pointers in existence. Allow deletion on other thread in this case. | 23 // null flag doesn't participate in the sequence checks. See DCHECK in |
20 DCHECK(sequence_checker_.CalledOnValidSequence() || HasOneRef()) | 24 // Invalidate() and IsValid(). |
21 << "WeakPtrs must be invalidated on the same sequenced thread."; | 25 |
22 is_valid_ = false; | 26 // Keep the object alive perpetually, even when there are no references to it. |
| 27 AddRef(); |
23 } | 28 } |
24 | 29 |
25 bool WeakReference::Flag::IsValid() const { | 30 WeakReference::Flag* WeakReference::Flag::NullFlag() { |
26 DCHECK(sequence_checker_.CalledOnValidSequence()) | 31 static Flag* g_null_flag = new Flag(kNullFlagTag); |
27 << "WeakPtrs must be checked on the same sequenced thread."; | 32 return g_null_flag; |
28 return is_valid_; | |
29 } | 33 } |
30 | 34 |
31 WeakReference::Flag::~Flag() { | 35 WeakReference::Flag::~Flag() {} |
32 } | |
33 | 36 |
34 WeakReference::WeakReference() { | 37 WeakReference::WeakReference() : flag_(Flag::NullFlag()) {} |
35 } | |
36 | |
37 WeakReference::WeakReference(const Flag* flag) : flag_(flag) { | |
38 } | |
39 | 38 |
40 WeakReference::~WeakReference() { | 39 WeakReference::~WeakReference() { |
41 } | 40 } |
42 | 41 |
43 WeakReference::WeakReference(WeakReference&& other) = default; | 42 WeakReference::WeakReference(const Flag* flag) : flag_(flag) {} |
| 43 |
| 44 WeakReference::WeakReference(WeakReference&& other) |
| 45 : flag_(std::move(other.flag_)) { |
| 46 other.flag_ = Flag::NullFlag(); |
| 47 } |
44 | 48 |
45 WeakReference::WeakReference(const WeakReference& other) = default; | 49 WeakReference::WeakReference(const WeakReference& other) = default; |
46 | 50 |
47 bool WeakReference::is_valid() const { return flag_.get() && flag_->IsValid(); } | 51 WeakReferenceOwner::WeakReferenceOwner() |
48 | 52 : flag_(WeakReference::Flag::NullFlag()) {} |
49 WeakReferenceOwner::WeakReferenceOwner() { | |
50 } | |
51 | 53 |
52 WeakReferenceOwner::~WeakReferenceOwner() { | 54 WeakReferenceOwner::~WeakReferenceOwner() { |
53 Invalidate(); | 55 Invalidate(); |
54 } | 56 } |
55 | 57 |
56 WeakReference WeakReferenceOwner::GetRef() const { | 58 WeakReference WeakReferenceOwner::GetRef() const { |
57 // If we hold the last reference to the Flag then create a new one. | 59 // If we hold the last reference to the Flag then create a new one. |
58 if (!HasRefs()) | 60 if (!HasRefs()) |
59 flag_ = new WeakReference::Flag(); | 61 flag_ = new WeakReference::Flag(); |
60 | 62 |
61 return WeakReference(flag_.get()); | 63 return WeakReference(flag_.get()); |
62 } | 64 } |
63 | 65 |
64 void WeakReferenceOwner::Invalidate() { | 66 void WeakReferenceOwner::Invalidate() { |
65 if (flag_.get()) { | 67 flag_->Invalidate(); |
66 flag_->Invalidate(); | 68 flag_ = WeakReference::Flag::NullFlag(); |
67 flag_ = NULL; | |
68 } | |
69 } | 69 } |
70 | 70 |
71 WeakPtrBase::WeakPtrBase() { | 71 WeakPtrBase::WeakPtrBase() { |
72 } | 72 } |
73 | 73 |
74 WeakPtrBase::~WeakPtrBase() { | 74 WeakPtrBase::~WeakPtrBase() { |
75 } | 75 } |
76 | 76 |
77 WeakPtrBase::WeakPtrBase(const WeakReference& ref) : ref_(ref) { | 77 WeakPtrBase::WeakPtrBase(const WeakReference& ref) : ref_(ref) { |
78 } | 78 } |
79 | 79 |
80 } // namespace internal | 80 } // namespace internal |
81 } // namespace base | 81 } // namespace base |
OLD | NEW |