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// Copyright 2015 the V8 project 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 V8_ATOMIC_UTILS_H_
#define V8_ATOMIC_UTILS_H_
#include <limits.h>
#include "src/base/atomicops.h"
#include "src/base/macros.h"
namespace v8 {
namespace internal {
template <class T>
class AtomicNumber {
public:
AtomicNumber() : value_(0) {}
explicit AtomicNumber(T initial) : value_(initial) {}
V8_INLINE void Increment(T increment) {
base::Barrier_AtomicIncrement(&value_,
static_cast<base::AtomicWord>(increment));
}
V8_INLINE T Value() { return static_cast<T>(base::Acquire_Load(&value_)); }
V8_INLINE void SetValue(T new_value) {
base::Release_Store(&value_, static_cast<base::AtomicWord>(new_value));
}
V8_INLINE T operator=(T value) {
SetValue(value);
return value;
}
private:
STATIC_ASSERT(sizeof(T) <= sizeof(base::AtomicWord));
base::AtomicWord value_;
};
// Flag using T atomically. Also accepts void* as T.
template <typename T>
class AtomicValue {
public:
AtomicValue() : value_(0) {}
explicit AtomicValue(T initial)
: value_(cast_helper<T>::to_storage_type(initial)) {}
V8_INLINE T Value() {
return cast_helper<T>::to_return_type(base::Acquire_Load(&value_));
}
V8_INLINE bool TrySetValue(T old_value, T new_value) {
return base::Release_CompareAndSwap(
&value_, cast_helper<T>::to_storage_type(old_value),
cast_helper<T>::to_storage_type(new_value)) ==
cast_helper<T>::to_storage_type(old_value);
}
V8_INLINE void SetValue(T new_value) {
base::Release_Store(&value_, cast_helper<T>::to_storage_type(new_value));
}
private:
STATIC_ASSERT(sizeof(T) <= sizeof(base::AtomicWord));
template <typename S>
struct cast_helper {
static base::AtomicWord to_storage_type(S value) {
return static_cast<base::AtomicWord>(value);
}
static S to_return_type(base::AtomicWord value) {
return static_cast<S>(value);
}
};
template <typename S>
struct cast_helper<S*> {
static base::AtomicWord to_storage_type(S* value) {
return reinterpret_cast<base::AtomicWord>(value);
}
static S* to_return_type(base::AtomicWord value) {
return reinterpret_cast<S*>(value);
}
};
base::AtomicWord value_;
};
// See utils.h for EnumSet. Storage is always base::AtomicWord.
// Requirements on E:
// - No explicit values.
// - E::kLastValue defined to be the last actually used value.
//
// Example:
// enum E { kA, kB, kC, kLastValue = kC };
template <class E>
class AtomicEnumSet {
public:
explicit AtomicEnumSet(base::AtomicWord bits = 0) : bits_(bits) {}
bool IsEmpty() const { return ToIntegral() == 0; }
bool Contains(E element) const { return (ToIntegral() & Mask(element)) != 0; }
bool ContainsAnyOf(const AtomicEnumSet& set) const {
return (ToIntegral() & set.ToIntegral()) != 0;
}
void RemoveAll() { base::Release_Store(&bits_, 0); }
bool operator==(const AtomicEnumSet& set) const {
return ToIntegral() == set.ToIntegral();
}
bool operator!=(const AtomicEnumSet& set) const {
return ToIntegral() != set.ToIntegral();
}
AtomicEnumSet<E> operator|(const AtomicEnumSet& set) const {
return AtomicEnumSet<E>(ToIntegral() | set.ToIntegral());
}
// The following operations modify the underlying storage.
#define ATOMIC_SET_WRITE(OP, NEW_VAL) \
do { \
base::AtomicWord old; \
do { \
old = base::Acquire_Load(&bits_); \
} while (base::Release_CompareAndSwap(&bits_, old, old OP NEW_VAL) != \
old); \
} while (false)
void Add(E element) { ATOMIC_SET_WRITE(|, Mask(element)); }
void Add(const AtomicEnumSet& set) { ATOMIC_SET_WRITE(|, set.ToIntegral()); }
void Remove(E element) { ATOMIC_SET_WRITE(&, ~Mask(element)); }
void Remove(const AtomicEnumSet& set) {
ATOMIC_SET_WRITE(&, ~set.ToIntegral());
}
void Intersect(const AtomicEnumSet& set) {
ATOMIC_SET_WRITE(&, set.ToIntegral());
}
#undef ATOMIC_SET_OP
private:
// Check whether there's enough storage to hold E.
STATIC_ASSERT(E::kLastValue < (sizeof(base::AtomicWord) * CHAR_BIT));
V8_INLINE base::AtomicWord ToIntegral() const {
return base::Acquire_Load(&bits_);
}
V8_INLINE base::AtomicWord Mask(E element) const {
return static_cast<base::AtomicWord>(1) << element;
}
base::AtomicWord bits_;
};
} // namespace internal
} // namespace v8
#endif // #define V8_ATOMIC_UTILS_H_
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