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Prefer std::atomic over MemoryBarrier #2

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Merged
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Jul 12, 2017
Merged

Prefer std::atomic over MemoryBarrier #2

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47 changes: 25 additions & 22 deletions port/atomic_pointer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,30 @@
namespace leveldb {
namespace port {

// AtomicPointer based on <cstdatomic> if available
#if defined(LEVELDB_ATOMIC_PRESENT)
class AtomicPointer {
private:
std::atomic<void*> rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* v) : rep_(v) { }
inline void* Acquire_Load() const {
return rep_.load(std::memory_order_acquire);
}
inline void Release_Store(void* v) {
rep_.store(v, std::memory_order_release);
}
inline void* NoBarrier_Load() const {
return rep_.load(std::memory_order_relaxed);
}
inline void NoBarrier_Store(void* v) {
rep_.store(v, std::memory_order_relaxed);
}
};

#else

// Define MemoryBarrier() if available
// Windows on x86
#if defined(OS_WIN) && defined(COMPILER_MSVC) && defined(ARCH_CPU_X86_FAMILY)
Expand Down Expand Up @@ -142,28 +166,6 @@ class AtomicPointer {
}
};

// AtomicPointer based on <cstdatomic>
#elif defined(LEVELDB_ATOMIC_PRESENT)
class AtomicPointer {
private:
std::atomic<void*> rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* v) : rep_(v) { }
inline void* Acquire_Load() const {
return rep_.load(std::memory_order_acquire);
}
inline void Release_Store(void* v) {
rep_.store(v, std::memory_order_release);
}
inline void* NoBarrier_Load() const {
return rep_.load(std::memory_order_relaxed);
}
inline void NoBarrier_Store(void* v) {
rep_.store(v, std::memory_order_relaxed);
}
};

// Atomic pointer based on sparc memory barriers
#elif defined(__sparcv9) && defined(__GNUC__)
class AtomicPointer {
Expand Down Expand Up @@ -228,6 +230,7 @@ class AtomicPointer {
#else
#error Please implement AtomicPointer for this platform.

#endif
#endif

#undef LEVELDB_HAVE_MEMORY_BARRIER
Expand Down