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#pragma once
#include "intrusive_ptr.h"
#include <util/system/compiler.h>
#if defined(_lsan_enabled_) || defined(_asan_enabled_)
#include <util/system/spinlock.h>
#endif
namespace NYT {
////////////////////////////////////////////////////////////////////////////////
//! Atomic pointer with split reference counting.
/*
* \see https://github.com/facebook/folly/blob/main/folly/concurrency/AtomicSharedPtr.h
*/
template <class T>
class TAtomicIntrusivePtr
{
public:
TAtomicIntrusivePtr() = default;
TAtomicIntrusivePtr(std::nullptr_t);
explicit TAtomicIntrusivePtr(TIntrusivePtr<T> other);
TAtomicIntrusivePtr(TAtomicIntrusivePtr&& other);
~TAtomicIntrusivePtr();
TAtomicIntrusivePtr& operator=(TIntrusivePtr<T> other);
TAtomicIntrusivePtr& operator=(std::nullptr_t);
TIntrusivePtr<T> Acquire() const;
TIntrusivePtr<T> Exchange(TIntrusivePtr<T> other);
void Store(TIntrusivePtr<T> other);
void Reset();
using TRawPtr = std::conditional_t<std::is_const_v<T>, const void*, void*>;
bool CompareAndSwap(TRawPtr& comparePtr, T* target);
bool CompareAndSwap(TRawPtr& comparePtr, TIntrusivePtr<T> target);
//! Result is only suitable for comparison, not dereference.
TRawPtr Get() const;
explicit operator bool() const;
private:
template <class U>
friend bool operator==(const TAtomicIntrusivePtr<U>& lhs, const TIntrusivePtr<U>& rhs);
template <class U>
friend bool operator==(const TIntrusivePtr<U>& lhs, const TAtomicIntrusivePtr<U>& rhs);
template <class U>
friend bool operator!=(const TAtomicIntrusivePtr<U>& lhs, const TIntrusivePtr<U>& rhs);
template <class U>
friend bool operator!=(const TIntrusivePtr<U>& lhs, const TAtomicIntrusivePtr<U>& rhs);
#if defined(_lsan_enabled_) || defined(_asan_enabled_)
::TSpinLock Lock_;
TIntrusivePtr<T> Ptr_;
#else
// Keeps packed pointer (localRefCount, objectPtr).
// Atomic ptr holds N references, where N = ReservedRefCount - localRefCount.
// LocalRefCount is incremented in Acquire method.
// When localRefCount exceeds ReservedRefCount / 2 a new portion of refs are required globally.
// This field is marked mutable in order to make Acquire const-qualified in accordance to its semantics.
mutable std::atomic<TPackedPtr> Ptr_ = 0;
constexpr static int CounterBits = PackedPtrTagBits;
constexpr static int ReservedRefCount = (1 << CounterBits) - 1;
// Consume ref if ownership is transferred.
static TPackedPtr AcquireObject(T* obj, bool consumeRef = false);
static void ReleaseObject(TPackedPtr packedPtr);
static void DoRelease(T* obj, int refs);
#endif
};
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT
#define ATOMIC_INTRUSIVE_PTR_INL_H_
#include "atomic_intrusive_ptr-inl.h"
#undef ATOMIC_INTRUSIVE_PTR_INL_H_
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