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#pragma once
#include <library/cpp/yt/misc/port.h>
#include <library/cpp/yt/assert/assert.h>
#include <atomic>
namespace NYT {
////////////////////////////////////////////////////////////////////////////////
//! A technical base class for ref-counted objects and promise states.
class TRefCountedBase
{
public:
TRefCountedBase() = default;
TRefCountedBase(const TRefCountedBase&) = delete;
TRefCountedBase(TRefCountedBase&&) = delete;
TRefCountedBase& operator=(const TRefCountedBase&) = delete;
TRefCountedBase& operator=(TRefCountedBase&&) = delete;
virtual ~TRefCountedBase() noexcept = default;
virtual void DestroyRefCounted() = 0;
};
////////////////////////////////////////////////////////////////////////////////
class TRefCounter
{
public:
//! Returns current number of strong references to the object.
/*!
* Note that you should never ever use this method in production code.
* This method is mainly for debugging purposes.
*/
int GetRefCount() const noexcept;
//! Increments the strong reference counter.
//! The current strong RC must be positive.
void Ref(int n = 1) const noexcept;
//! Increments the strong reference counter.
//! The current strong RC may be zero.
void DangerousRef(int n = 1) const noexcept;
//! Increments the strong reference counter if it is not null.
bool TryRef() const noexcept;
//! Decrements the strong reference counter.
bool Unref(int n = 1) const;
//! Returns current number of weak references to the object.
int GetWeakRefCount() const noexcept;
//! Increments the weak reference counter.
void WeakRef() const noexcept;
//! Decrements the weak reference counter.
bool WeakUnref() const;
private:
// NB: Must we 64 bit as TAtomicIntrusivePtr grabs refs in 64K batches.
using TRefCount = i64;
mutable std::atomic<TRefCount> StrongCount_ = 1;
mutable std::atomic<TRefCount> WeakCount_ = 1;
};
////////////////////////////////////////////////////////////////////////////////
template <class T>
const TRefCounter* GetRefCounter(const T* obj);
template <class T>
void DestroyRefCounted(const T* obj);
template <class T>
void DeallocateRefCounted(const T* obj);
////////////////////////////////////////////////////////////////////////////////
template <class T>
void Ref(T* obj, int n = 1);
template <class T>
void Unref(T* obj, int n = 1);
////////////////////////////////////////////////////////////////////////////////
class TRefCounted
: public TRefCountedBase
, public TRefCounter
{
public:
void Unref() const;
void WeakUnref() const;
protected:
template <class T>
static void DestroyRefCountedImpl(T* obj);
};
////////////////////////////////////////////////////////////////////////////////
// Forward declaration.
template <class T>
class TIntrusivePtr;
using TRefCountedPtr = TIntrusivePtr<TRefCounted>;
// A bunch of helpful macros that enable working with intrusive pointers to incomplete types.
/*
* Typically when you have a forward-declared type |T| and an instance
* of |TIntrusivePtr<T>| you need the complete definition of |T| to work with
* the pointer even if you're not actually using the members of |T|.
* E.g. the dtor of |TIntrusivePtr<T>|, should you ever need it, must be able
* to unref an instance of |T| and eventually destroy it.
* This may force #inclusion of way more headers than really seems necessary.
*
* |DECLARE_REFCOUNTED_STRUCT|, |DECLARE_REFCOUNTED_CLASS|, and |DEFINE_REFCOUNTED_TYPE|
* alleviate this issue by forcing TIntrusivePtr to work with the free-standing overloads
* of |Ref| and |Unref| instead of their template version.
* These overloads are declared together with the forward declaration of |T| and
* are subsequently defined afterwards.
*/
#define DECLARE_REFCOUNTED_TYPE(type) \
using type ## Ptr = ::NYT::TIntrusivePtr<type>; \
\
[[maybe_unused]] YT_ATTRIBUTE_USED const ::NYT::TRefCounter* GetRefCounter(const type* obj); \
[[maybe_unused]] YT_ATTRIBUTE_USED void DestroyRefCounted(const type* obj); \
[[maybe_unused]] YT_ATTRIBUTE_USED void DeallocateRefCounted(const type* obj);
//! Forward-declares a class type, defines an intrusive pointer for it, and finally
//! declares Ref/Unref overloads. Use this macro in |public.h|-like files.
#define DECLARE_REFCOUNTED_CLASS(type) \
class type; \
DECLARE_REFCOUNTED_TYPE(type)
//! Forward-declares a struct type, defines an intrusive pointer for it, and finally
//! declares Ref/Unref overloads. Use this macro in |public.h|-like files.
#define DECLARE_REFCOUNTED_STRUCT(type) \
struct type; \
DECLARE_REFCOUNTED_TYPE(type)
//! Provides implementations for Ref/Unref overloads. Use this macro right
//! after the type's full definition.
#define DEFINE_REFCOUNTED_TYPE(type) \
[[maybe_unused]] YT_ATTRIBUTE_USED Y_FORCE_INLINE const ::NYT::TRefCounter* GetRefCounter(const type* obj) \
{ \
return ::NYT::NDetail::TRefCountedTraits<type>::GetRefCounter(obj); \
} \
[[maybe_unused]] YT_ATTRIBUTE_USED Y_FORCE_INLINE void DestroyRefCounted(const type* obj) \
{ \
::NYT::NDetail::TRefCountedTraits<type>::Destroy(obj); \
} \
[[maybe_unused]] YT_ATTRIBUTE_USED Y_FORCE_INLINE void DeallocateRefCounted(const type* obj) \
{ \
::NYT::NDetail::TRefCountedTraits<type>::Deallocate(obj); \
}
//! Provides weak implementations for Ref/Unref overloads.
//! Do not use if unsure.
#define DEFINE_WEAK_REFCOUNTED_TYPE(type) \
[[maybe_unused]] Y_WEAK YT_ATTRIBUTE_USED const ::NYT::TRefCounter* GetRefCounter(const type*) \
{ \
YT_ABORT(); \
} \
[[maybe_unused]] Y_WEAK YT_ATTRIBUTE_USED void DestroyRefCounted(const type*) \
{ \
YT_ABORT(); \
} \
[[maybe_unused]] Y_WEAK YT_ATTRIBUTE_USED void DeallocateRefCounted(const type*) \
{ \
YT_ABORT(); \
}
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT
#define REF_COUNTED_INL_H_
#include "ref_counted-inl.h"
#undef REF_COUNTED_INL_H_
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