Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 1 | // Copyright 2015 the V8 project 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 V8_ATOMIC_UTILS_H_ |
| 6 | #define V8_ATOMIC_UTILS_H_ |
| 7 | |
| 8 | #include <limits.h> |
| 9 | |
| 10 | #include "src/base/atomicops.h" |
| 11 | #include "src/base/macros.h" |
| 12 | |
| 13 | namespace v8 { |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame] | 14 | namespace base { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 15 | |
| 16 | template <class T> |
| 17 | class AtomicNumber { |
| 18 | public: |
| 19 | AtomicNumber() : value_(0) {} |
| 20 | explicit AtomicNumber(T initial) : value_(initial) {} |
| 21 | |
| 22 | // Returns the newly set value. |
| 23 | V8_INLINE T Increment(T increment) { |
| 24 | return static_cast<T>(base::Barrier_AtomicIncrement( |
| 25 | &value_, static_cast<base::AtomicWord>(increment))); |
| 26 | } |
| 27 | |
| 28 | V8_INLINE T Value() { return static_cast<T>(base::Acquire_Load(&value_)); } |
| 29 | |
| 30 | V8_INLINE void SetValue(T new_value) { |
| 31 | base::Release_Store(&value_, static_cast<base::AtomicWord>(new_value)); |
| 32 | } |
| 33 | |
| 34 | V8_INLINE T operator=(T value) { |
| 35 | SetValue(value); |
| 36 | return value; |
| 37 | } |
| 38 | |
| 39 | private: |
| 40 | STATIC_ASSERT(sizeof(T) <= sizeof(base::AtomicWord)); |
| 41 | |
| 42 | base::AtomicWord value_; |
| 43 | }; |
| 44 | |
| 45 | |
| 46 | // Flag using T atomically. Also accepts void* as T. |
| 47 | template <typename T> |
| 48 | class AtomicValue { |
| 49 | public: |
| 50 | AtomicValue() : value_(0) {} |
| 51 | |
| 52 | explicit AtomicValue(T initial) |
| 53 | : value_(cast_helper<T>::to_storage_type(initial)) {} |
| 54 | |
| 55 | V8_INLINE T Value() { |
| 56 | return cast_helper<T>::to_return_type(base::Acquire_Load(&value_)); |
| 57 | } |
| 58 | |
| 59 | V8_INLINE bool TrySetValue(T old_value, T new_value) { |
| 60 | return base::Release_CompareAndSwap( |
| 61 | &value_, cast_helper<T>::to_storage_type(old_value), |
| 62 | cast_helper<T>::to_storage_type(new_value)) == |
| 63 | cast_helper<T>::to_storage_type(old_value); |
| 64 | } |
| 65 | |
| 66 | V8_INLINE void SetValue(T new_value) { |
| 67 | base::Release_Store(&value_, cast_helper<T>::to_storage_type(new_value)); |
| 68 | } |
| 69 | |
| 70 | private: |
| 71 | STATIC_ASSERT(sizeof(T) <= sizeof(base::AtomicWord)); |
| 72 | |
| 73 | template <typename S> |
| 74 | struct cast_helper { |
| 75 | static base::AtomicWord to_storage_type(S value) { |
| 76 | return static_cast<base::AtomicWord>(value); |
| 77 | } |
| 78 | static S to_return_type(base::AtomicWord value) { |
| 79 | return static_cast<S>(value); |
| 80 | } |
| 81 | }; |
| 82 | |
| 83 | template <typename S> |
| 84 | struct cast_helper<S*> { |
| 85 | static base::AtomicWord to_storage_type(S* value) { |
| 86 | return reinterpret_cast<base::AtomicWord>(value); |
| 87 | } |
| 88 | static S* to_return_type(base::AtomicWord value) { |
| 89 | return reinterpret_cast<S*>(value); |
| 90 | } |
| 91 | }; |
| 92 | |
| 93 | base::AtomicWord value_; |
| 94 | }; |
| 95 | |
| 96 | |
| 97 | // See utils.h for EnumSet. Storage is always base::AtomicWord. |
| 98 | // Requirements on E: |
| 99 | // - No explicit values. |
| 100 | // - E::kLastValue defined to be the last actually used value. |
| 101 | // |
| 102 | // Example: |
| 103 | // enum E { kA, kB, kC, kLastValue = kC }; |
| 104 | template <class E> |
| 105 | class AtomicEnumSet { |
| 106 | public: |
| 107 | explicit AtomicEnumSet(base::AtomicWord bits = 0) : bits_(bits) {} |
| 108 | |
| 109 | bool IsEmpty() const { return ToIntegral() == 0; } |
| 110 | |
| 111 | bool Contains(E element) const { return (ToIntegral() & Mask(element)) != 0; } |
| 112 | bool ContainsAnyOf(const AtomicEnumSet& set) const { |
| 113 | return (ToIntegral() & set.ToIntegral()) != 0; |
| 114 | } |
| 115 | |
| 116 | void RemoveAll() { base::Release_Store(&bits_, 0); } |
| 117 | |
| 118 | bool operator==(const AtomicEnumSet& set) const { |
| 119 | return ToIntegral() == set.ToIntegral(); |
| 120 | } |
| 121 | |
| 122 | bool operator!=(const AtomicEnumSet& set) const { |
| 123 | return ToIntegral() != set.ToIntegral(); |
| 124 | } |
| 125 | |
| 126 | AtomicEnumSet<E> operator|(const AtomicEnumSet& set) const { |
| 127 | return AtomicEnumSet<E>(ToIntegral() | set.ToIntegral()); |
| 128 | } |
| 129 | |
| 130 | // The following operations modify the underlying storage. |
| 131 | |
| 132 | #define ATOMIC_SET_WRITE(OP, NEW_VAL) \ |
| 133 | do { \ |
| 134 | base::AtomicWord old; \ |
| 135 | do { \ |
| 136 | old = base::Acquire_Load(&bits_); \ |
| 137 | } while (base::Release_CompareAndSwap(&bits_, old, old OP NEW_VAL) != \ |
| 138 | old); \ |
| 139 | } while (false) |
| 140 | |
| 141 | void Add(E element) { ATOMIC_SET_WRITE(|, Mask(element)); } |
| 142 | |
| 143 | void Add(const AtomicEnumSet& set) { ATOMIC_SET_WRITE(|, set.ToIntegral()); } |
| 144 | |
| 145 | void Remove(E element) { ATOMIC_SET_WRITE(&, ~Mask(element)); } |
| 146 | |
| 147 | void Remove(const AtomicEnumSet& set) { |
| 148 | ATOMIC_SET_WRITE(&, ~set.ToIntegral()); |
| 149 | } |
| 150 | |
| 151 | void Intersect(const AtomicEnumSet& set) { |
| 152 | ATOMIC_SET_WRITE(&, set.ToIntegral()); |
| 153 | } |
| 154 | |
| 155 | #undef ATOMIC_SET_OP |
| 156 | |
| 157 | private: |
| 158 | // Check whether there's enough storage to hold E. |
| 159 | STATIC_ASSERT(E::kLastValue < (sizeof(base::AtomicWord) * CHAR_BIT)); |
| 160 | |
| 161 | V8_INLINE base::AtomicWord ToIntegral() const { |
| 162 | return base::Acquire_Load(&bits_); |
| 163 | } |
| 164 | |
| 165 | V8_INLINE base::AtomicWord Mask(E element) const { |
| 166 | return static_cast<base::AtomicWord>(1) << element; |
| 167 | } |
| 168 | |
| 169 | base::AtomicWord bits_; |
| 170 | }; |
| 171 | |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame] | 172 | } // namespace base |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 173 | } // namespace v8 |
| 174 | |
| 175 | #endif // #define V8_ATOMIC_UTILS_H_ |