FM / util

/usr/local/lib64/python3.6/site-packages/torch/include/c10/util/

/usr/local/lib64/python3.6/site-packages/torch/include/c10/util

Name	Size	Mode	Actions
accumulate.h	4205	0644	edit dl rm
AlignOf.h	4835	0644	edit dl rm
Array.h	11354	0644	edit dl rm
ArrayRef.h	9058	0644	edit dl rm
Backtrace.h	364	0644	edit dl rm
BFloat16-inl.h	9222	0644	edit dl rm
BFloat16-math.h	5217	0644	edit dl rm
BFloat16.h	2372	0644	edit dl rm
Bitset.h	3414	0644	edit dl rm
C++17.h	13329	0644	edit dl rm
complex.h	17542	0644	edit dl rm
complex_math.h	10902	0644	edit dl rm
complex_utils.h	958	0644	edit dl rm
ConstexprCrc.h	6633	0644	edit dl rm
copysign.h	866	0644	edit dl rm
DeadlockDetection.h	1920	0644	edit dl rm
Deprecated.h	3579	0644	edit dl rm
either.h	6423	0644	edit dl rm
env.h	835	0644	edit dl rm
Exception.h	24723	0644	edit dl rm
ExclusivelyOwned.h	4759	0644	edit dl rm
Flags.h	10056	0644	edit dl rm
flat_hash_map.h	61655	0644	edit dl rm
FunctionRef.h	2301	0644	edit dl rm
Half-inl.h	8674	0644	edit dl rm
Half.h	18965	0644	edit dl rm
hash.h	5084	0644	edit dl rm
IdWrapper.h	2348	0644	edit dl rm
intrusive_ptr.h	35563	0644	edit dl rm
in_place.h	350	0644	edit dl rm
irange.h	2679	0644	edit dl rm
LeftRight.h	6016	0644	edit dl rm
llvmMathExtras.h	29168	0644	edit dl rm
Logging.h	11256	0644	edit dl rm
logging_is_google_glog.h	2031	0644	edit dl rm
logging_is_not_google_glog.h	8271	0644	edit dl rm
MathConstants.h	858	0644	edit dl rm
math_compat.h	7296	0644	edit dl rm
MaybeOwned.h	6689	0644	edit dl rm
Metaprogramming.h	15288	0644	edit dl rm
numa.h	696	0644	edit dl rm
Optional.h	35592	0644	edit dl rm
order_preserving_flat_hash_map.h	65482	0644	edit dl rm
overloaded.h	709	0644	edit dl rm
python_stub.h	56	0644	edit dl rm
qint8.h	472	0644	edit dl rm
qint32.h	319	0644	edit dl rm
quint4x2.h	366	0644	edit dl rm
quint8.h	320	0644	edit dl rm
Registry.h	12242	0644	edit dl rm
reverse_iterator.h	8796	0644	edit dl rm
ScopeExit.h	1345	0644	edit dl rm
signal_handler.h	3154	0644	edit dl rm
SmallBuffer.h	1243	0644	edit dl rm
SmallVector.h	34456	0644	edit dl rm
sparse_bitset.h	26511	0644	edit dl rm
StringUtil.h	4538	0644	edit dl rm
string_utils.h	3989	0644	edit dl rm
string_view.h	20189	0644	edit dl rm
tempfile.h	6029	0644	edit dl rm
ThreadLocal.h	3883	0644	edit dl rm
ThreadLocalDebugInfo.h	2603	0644	edit dl rm
thread_name.h	148	0644	edit dl rm
Type.h	607	0644	edit dl rm
TypeCast.h	6972	0644	edit dl rm
typeid.h	18793	0644	edit dl rm
TypeIndex.h	5251	0644	edit dl rm
TypeList.h	16901	0644	edit dl rm
TypeTraits.h	5368	0644	edit dl rm
Unicode.h	295	0644	edit dl rm
UniqueVoidPtr.h	4117	0644	edit dl rm
Unroll.h	667	0644	edit dl rm
variant.h	95182	0644	edit dl rm
win32-headers.h	858	0644	edit dl rm

Edit: /usr/local/lib64/python3.6/site-packages/torch/include/c10/util/intrusive_ptr.h (35563B)

#pragma once

#include <c10/util/C++17.h>
#include <c10/util/Exception.h>
#include <c10/util/ExclusivelyOwned.h>
#include <c10/util/MaybeOwned.h>
#include <atomic>
#include <stdexcept>

namespace pybind11 {
template <typename, typename...>
class class_;
}

namespace c10 {
class intrusive_ptr_target;
namespace raw {
namespace weak_intrusive_ptr {
inline void incref(intrusive_ptr_target* self);
}
namespace intrusive_ptr {
inline void incref(intrusive_ptr_target* self);
}

template <typename TTarget>
struct ExclusivelyOwnedTraits;

// constructor tag used by intrusive_ptr constructors
struct DontIncreaseRefcount {};
} // namespace raw
/**
 * intrusive_ptr<T> is an alternative to shared_ptr<T> that has better
 * performance because it does the refcounting intrusively
 * (i.e. in a member of the object itself).
 * Your class T needs to inherit from intrusive_ptr_target to allow it to be
 * used in an intrusive_ptr<T>. Your class's constructor should not allow
 *`this` to escape to other threads or create an intrusive_ptr from `this`.
 */

// Note [Stack allocated intrusive_ptr_target safety]
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// A well known problem with std::enable_shared_from_this is that it
// allows you to create a std::shared_ptr from a stack allocated object,
// which is totally bogus because the object will die once you return
// from the stack.  In intrusive_ptr, we can detect that this has occurred,
// because we set the refcount/weakcount of objects which inherit from
// intrusive_ptr_target to zero, *unless* we can prove that the object
// was dynamically allocated (e.g., via make_intrusive).
//
// Thus, whenever you transmute a T* into a intrusive_ptr<T>, we check
// and make sure that the refcount isn't zero (or, a more subtle
// test for weak_intrusive_ptr<T>, for which the refcount may validly
// be zero, but the weak refcount better not be zero), because that
// tells us if the object was allocated by us.  If it wasn't, no
// intrusive_ptr for you!

class C10_API intrusive_ptr_target {
  // Note [Weak references for intrusive refcounting]
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  // Here's the scheme:
  //
  //  - refcount == number of strong references to the object
  //    weakcount == number of weak references to the object,
  //      plus one more if refcount > 0
  //    An invariant: refcount > 0  =>  weakcount > 0
  //
  //  - THStorage stays live as long as there are any strong
  //    or weak pointers to it (weakcount > 0, since strong
  //    references count as a +1 to weakcount)
  //
  //  - finalizers are called and data_ptr is deallocated when refcount == 0
  //
  //  - Once refcount == 0, it can never again be > 0 (the transition
  //    from > 0 to == 0 is monotonic)
  //
  //  - When you access THStorage via a weak pointer, you must
  //    atomically increment the use count, if it is greater than 0.
  //    If it is not, you must report that the storage is dead.
  //
  mutable std::atomic<size_t> refcount_;
  mutable std::atomic<size_t> weakcount_;

template <typename T, typename NullType>
  friend class intrusive_ptr;
  friend inline void raw::intrusive_ptr::incref(intrusive_ptr_target* self);

template <typename T, typename NullType>
  friend class weak_intrusive_ptr;
  friend inline void raw::weak_intrusive_ptr::incref(
      intrusive_ptr_target* self);

template <typename T>
  friend struct ExclusivelyOwnedTraits;

protected:
  // protected destructor. We never want to destruct intrusive_ptr_target*
  // directly.
  virtual ~intrusive_ptr_target() {
// Disable -Wterminate and -Wexceptions so we're allowed to use assertions
// (i.e. throw exceptions) in a destructor.
// We also have to disable -Wunknown-warning-option and -Wpragmas, because
// some other compilers don't know about -Wterminate or -Wexceptions and
// will show a warning about unknown warning options otherwise.
#if defined(_MSC_VER) && !defined(__clang__)
#pragma warning(push)
#pragma warning( \
    disable : 4297) // function assumed not to throw an exception but does
#else
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Wunknown-warning-option"
#pragma GCC diagnostic ignored "-Wterminate"
#pragma GCC diagnostic ignored "-Wexceptions"
#endif
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        refcount_.load() == 0,
        "Tried to destruct an intrusive_ptr_target that still has intrusive_ptr to it");
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        // See ~intrusive_ptr for optimization that will frequently result in 1
        // at destruction time.
        weakcount_.load() == 1 || weakcount_.load() == 0,
        "Tried to destruct an intrusive_ptr_target that still has weak_intrusive_ptr to it");
#if defined(_MSC_VER) && !defined(__clang__)
#pragma warning(pop)
#else
#pragma GCC diagnostic pop
#endif
  }

constexpr intrusive_ptr_target() noexcept : refcount_(0), weakcount_(0) {}

// intrusive_ptr_target supports copy and move: but refcount and weakcount
  // don't participate (since they are intrinsic properties of the memory
  // location)
  intrusive_ptr_target(intrusive_ptr_target&& other) noexcept
      : intrusive_ptr_target() {}
  intrusive_ptr_target& operator=(intrusive_ptr_target&& other) noexcept {
    return *this;
  }
  intrusive_ptr_target(const intrusive_ptr_target& other) noexcept
      : intrusive_ptr_target() {}
  intrusive_ptr_target& operator=(const intrusive_ptr_target& other) noexcept {
    return *this;
  }

private:
  /**
   * This is called when refcount reaches zero.
   * You can override this to release expensive resources.
   * There might still be weak references, so your object might not get
   * destructed yet, but you can assume the object isn't used anymore,
   * i.e. no more calls to methods or accesses to members (we just can't
   * destruct it yet because we need the weakcount accessible).
   *
   * Even if there are no weak references (i.e. your class is about to be
   * destructed), this function is guaranteed to be called first.
   * However, if you use your class for an object on the stack that is
   * destructed by the scope (i.e. without intrusive_ptr), this function will
   * not be called.
   */
  virtual void release_resources() {}
};

namespace detail {
template <class TTarget>
struct intrusive_target_default_null_type final {
  static constexpr TTarget* singleton() noexcept {
    return nullptr;
  }
};

template <class TTarget, class ToNullType, class FromNullType>
TTarget* assign_ptr_(TTarget* rhs) {
  if (FromNullType::singleton() == rhs) {
    return ToNullType::singleton();
  } else {
    return rhs;
  }
}

// Increment needs to be acquire-release to make use_count() and
// unique() reliable.
inline size_t atomic_refcount_increment(std::atomic<size_t>& refcount) {
  return refcount.fetch_add(1, std::memory_order_acq_rel) + 1;
}

// weak_use_count() is only used for testing, so we don't need it to
// be reliable. Relaxed should be fine.
inline size_t atomic_weakcount_increment(std::atomic<size_t>& weakcount) {
  return weakcount.fetch_add(1, std::memory_order_relaxed) + 1;
}

// Both decrements need to be acquire-release for correctness. See
// e.g. std::shared_ptr implementation.
inline size_t atomic_refcount_decrement(std::atomic<size_t>& refcount) {
  return refcount.fetch_sub(1, std::memory_order_acq_rel) - 1;
}

inline size_t atomic_weakcount_decrement(std::atomic<size_t>& weakcount) {
  return weakcount.fetch_sub(1, std::memory_order_acq_rel) - 1;
}

} // namespace detail

template <class TTarget, class NullType>
class weak_intrusive_ptr;

template <
    class TTarget,
    class NullType = detail::intrusive_target_default_null_type<TTarget>>
class intrusive_ptr final {
 private:
//  the following static assert would be nice to have but it requires
//  the target class T to be fully defined when intrusive_ptr<T> is instantiated
//  this is a problem for classes that contain pointers to themselves
//  static_assert(
//      std::is_base_of<intrusive_ptr_target, TTarget>::value,
//      "intrusive_ptr can only be used for classes that inherit from
//      intrusive_ptr_target.");
#ifndef _WIN32
  // This static_assert triggers on MSVC
  //  error C2131: expression did not evaluate to a constant
  static_assert(
      NullType::singleton() == NullType::singleton(),
      "NullType must have a constexpr singleton() method");
#endif
  static_assert(
      std::is_base_of<
          TTarget,
          typename std::remove_pointer<decltype(NullType::singleton())>::type>::
          value,
      "NullType::singleton() must return a element_type* pointer");

TTarget* target_;

template <typename T>
  friend struct ExclusivelyOwnedTraits;
  template <class TTarget2, class NullType2>
  friend class intrusive_ptr;
  friend class weak_intrusive_ptr<TTarget, NullType>;

// Make pybind11::class_ be a friend class of intrusive_ptr, so that custom
  // smart holder in pybind11 could access the private constructor of
  // intrusive_ptr(T*) which took the ownership of the object. This is required
  // by customer holder macro PYBIND11_DECLARE_HOLDER_TYPE, where it uses
  // intrusive_ptr(TTarget*) to initialize and take ownership of the object. For
  // details, see
  // https://pybind11.readthedocs.io/en/stable/advanced/smart_ptrs.html#custom-smart-pointers
  template <typename, typename...>
  friend class pybind11::class_;

void retain_() {
    if (target_ != NullType::singleton()) {
      size_t new_refcount =
          detail::atomic_refcount_increment(target_->refcount_);
      TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
          new_refcount != 1,
          "intrusive_ptr: Cannot increase refcount after it reached zero.");
    }
  }

void reset_() noexcept {
    if (target_ != NullType::singleton() &&
        detail::atomic_refcount_decrement(target_->refcount_) == 0) {
      // justification for const_cast: release_resources is basically a
      // destructor and a destructor always mutates the object, even for const
      // objects. NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDelete)
      const_cast<std::remove_const_t<TTarget>*>(target_)->release_resources();

// See comment above about weakcount. As long as refcount>0,
      // weakcount is one larger than the actual number of weak references.
      // So we need to decrement it here.
      if (target_->weakcount_.load(std::memory_order_acquire) == 1 ||
          detail::atomic_weakcount_decrement(target_->weakcount_) == 0) {
        delete target_;
      }
    }
    target_ = NullType::singleton();
  }

// raw pointer constructors are not public because we shouldn't make
  // intrusive_ptr out of raw pointers except from inside the make_intrusive(),
  // reclaim() and weak_intrusive_ptr::lock() implementations.

// This constructor will increase the ref counter for you.
  // This constructor will be used by the make_intrusive(), and also pybind11,
  // which wrap the intrusive_ptr holder around the raw pointer and incref
  // correspondingly (pybind11 requires raw pointer constructor to incref by
  // default).
  explicit intrusive_ptr(TTarget* target)
      : intrusive_ptr(target, raw::DontIncreaseRefcount{}) {
    if (target_ != NullType::singleton()) {
      // We just created result.target_, so we know no other thread has
      // access to it, so we know we needn't care about memory ordering.
      // (On x86_64, a store with memory_order_relaxed generates a plain old
      // `mov`, whereas an atomic increment does a lock-prefixed `add`, which is
      // much more expensive: https://godbolt.org/z/eKPzj8.)
      TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
          target_->refcount_ == 0 && target_->weakcount_ == 0,
          "intrusive_ptr: Newly-created target had non-zero refcounts. Does its "
          "constructor do something strange like incref or create an "
          "intrusive_ptr from `this`?");
      target_->refcount_.store(1, std::memory_order_relaxed);
      target_->weakcount_.store(1, std::memory_order_relaxed);
    }
  }

public:
  using element_type = TTarget;

intrusive_ptr() noexcept
      : intrusive_ptr(NullType::singleton(), raw::DontIncreaseRefcount{}) {}

// This constructor will not increase the ref counter for you.
  // We use the tagged dispatch mechanism to explicitly mark this constructor
  // to not increase the refcount
  explicit intrusive_ptr(TTarget* target, raw::DontIncreaseRefcount) noexcept
      : target_(target) {}

intrusive_ptr(intrusive_ptr&& rhs) noexcept : target_(rhs.target_) {
    rhs.target_ = NullType::singleton();
  }

template <class From, class FromNullType>
  /* implicit */ intrusive_ptr(intrusive_ptr<From, FromNullType>&& rhs) noexcept
      : target_(
            detail::assign_ptr_<TTarget, NullType, FromNullType>(rhs.target_)) {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. intrusive_ptr move constructor got pointer of wrong type.");
    rhs.target_ = FromNullType::singleton();
  }

intrusive_ptr(const intrusive_ptr& rhs) : target_(rhs.target_) {
    retain_();
  }

template <class From, class FromNullType>
  /* implicit */ intrusive_ptr(const intrusive_ptr<From, FromNullType>& rhs)
      : target_(
            detail::assign_ptr_<TTarget, NullType, FromNullType>(rhs.target_)) {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. intrusive_ptr copy constructor got pointer of wrong type.");
    retain_();
  }

~intrusive_ptr() noexcept {
    reset_();
  }

intrusive_ptr& operator=(intrusive_ptr&& rhs) & noexcept {
    return operator=<TTarget, NullType>(std::move(rhs));
  }

template <class From, class FromNullType>
  intrusive_ptr& operator=(intrusive_ptr<From, FromNullType>&& rhs) & noexcept {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. intrusive_ptr move assignment got pointer of wrong type.");
    intrusive_ptr tmp = std::move(rhs);
    swap(tmp);
    return *this;
  }

intrusive_ptr& operator=(const intrusive_ptr& rhs) & noexcept {
    return operator=<TTarget, NullType>(rhs);
  }

template <class From, class FromNullType>
  intrusive_ptr& operator=(const intrusive_ptr<From, NullType>& rhs) & {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. intrusive_ptr copy assignment got pointer of wrong type.");
    intrusive_ptr tmp = rhs;
    swap(tmp);
    return *this;
  }

TTarget* get() const noexcept {
    return target_;
  }

TTarget& operator*() const noexcept {
    return *target_;
  }

TTarget* operator->() const noexcept {
    // NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDelete)
    return target_;
  }

operator bool() const noexcept {
    return target_ != NullType::singleton();
  }

void reset() noexcept {
    reset_();
  }

void swap(intrusive_ptr& rhs) noexcept {
    TTarget* tmp = target_;
    target_ = rhs.target_;
    rhs.target_ = tmp;
  }

// We do a lot of null-pointer checks in our code, good to have this be cheap.
  bool defined() const noexcept {
    return target_ != NullType::singleton();
  }

size_t use_count() const noexcept {
    if (target_ == NullType::singleton()) {
      return 0;
    }
    return target_->refcount_.load(std::memory_order_acquire);
  }

size_t weak_use_count() const noexcept {
    if (target_ == NullType::singleton()) {
      return 0;
    }
    return target_->weakcount_.load(std::memory_order_acquire);
  }

bool unique() const noexcept {
    return use_count() == 1;
  }

/**
   * Returns an owning (!) pointer to the underlying object and makes the
   * intrusive_ptr instance invalid. That means the refcount is not decreased.
   * You *must* put the returned pointer back into a intrusive_ptr using
   * intrusive_ptr::reclaim(ptr) to properly destruct it.
   * This is helpful for C APIs.
   */
  TTarget* release() noexcept {
    // NOLINTNEXTLINE(clang-analyzer-core.uninitialized.Assign)
    TTarget* result = target_;
    target_ = NullType::singleton();
    return result;
  }

/**
   * Takes an owning pointer to TTarget* and creates an intrusive_ptr that takes
   * over ownership. That means the refcount is not increased.
   * This is the counter-part to intrusive_ptr::release() and the pointer
   * passed in *must* have been created using intrusive_ptr::release().
   */
  static intrusive_ptr reclaim(TTarget* owning_ptr) {
    return intrusive_ptr(owning_ptr, raw::DontIncreaseRefcount{});
  }

/**
   * Allocate a heap object with args and wrap it inside a intrusive_ptr and
   * incref. This is a helper function to let make_intrusive() access private
   * intrusive_ptr constructors.
   */
  template <class... Args>
  static intrusive_ptr make(Args&&... args) {
    return intrusive_ptr(new TTarget(std::forward<Args>(args)...));
  }

/**
   * Turn a new instance of TTarget (e.g., literally allocated
   * using new TTarget(...) into an intrusive_ptr.  If possible,
   * use intrusive_ptr::make instead which statically guarantees
   * that the allocation was done properly.
   *
   * At the moment, the only reason this method exists is because
   * pybind11 holder types expect to be able to allocate in
   * this way (because pybind11 handles the new allocation itself).
   */
  static intrusive_ptr unsafe_steal_from_new(TTarget* raw_ptr) {
    return intrusive_ptr(raw_ptr);
  }

/**
   * Turn a **non-owning raw pointer** to an intrusive_ptr.  It is
   * the moral equivalent of enable_shared_from_this on a shared pointer.
   *
   * This method is only valid for objects that are already live.  If
   * you are looking for the moral equivalent of unique_ptr<T>(T*)
   * constructor, see steal_from_new.
   *
   * TODO: https://github.com/pytorch/pytorch/issues/56482
   */
  static intrusive_ptr unsafe_reclaim_from_nonowning(TTarget* raw_ptr) {
    // See Note [Stack allocated intrusive_ptr_target safety]
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        raw_ptr == NullType::singleton() || raw_ptr->refcount_.load() > 0,
        "intrusive_ptr: Can only reclaim pointers that are owned by someone");
    auto ptr = reclaim(raw_ptr); // doesn't increase refcount
    ptr.retain_();
    return ptr;
  }
};

template <
    class TTarget,
    class NullType = detail::intrusive_target_default_null_type<TTarget>,
    class... Args>
inline intrusive_ptr<TTarget, NullType> make_intrusive(Args&&... args) {
  return intrusive_ptr<TTarget, NullType>::make(std::forward<Args>(args)...);
}

template <class TTarget, class NullType>
inline void swap(
    intrusive_ptr<TTarget, NullType>& lhs,
    intrusive_ptr<TTarget, NullType>& rhs) noexcept {
  lhs.swap(rhs);
}

// To allow intrusive_ptr inside std::map or std::set, we need operator<
template <class TTarget1, class NullType1, class TTarget2, class NullType2>
inline bool operator<(
    const intrusive_ptr<TTarget1, NullType1>& lhs,
    const intrusive_ptr<TTarget2, NullType2>& rhs) noexcept {
  return lhs.get() < rhs.get();
}

template <class TTarget1, class NullType1, class TTarget2, class NullType2>
inline bool operator==(
    const intrusive_ptr<TTarget1, NullType1>& lhs,
    const intrusive_ptr<TTarget2, NullType2>& rhs) noexcept {
  return lhs.get() == rhs.get();
}

template <class TTarget1, class NullType1, class TTarget2, class NullType2>
inline bool operator!=(
    const intrusive_ptr<TTarget1, NullType1>& lhs,
    const intrusive_ptr<TTarget2, NullType2>& rhs) noexcept {
  return !operator==(lhs, rhs);
}

template <typename T>
struct MaybeOwnedTraits<c10::intrusive_ptr<T>> {
  using owned_type = c10::intrusive_ptr<T>;
  using borrow_type = c10::intrusive_ptr<T>;

static borrow_type createBorrow(const owned_type& from) {
    return borrow_type::reclaim(from.get());
  }

static void assignBorrow(borrow_type& lhs, const borrow_type& rhs) {
    lhs.release();
    lhs = borrow_type::reclaim(rhs.get());
  }

static void destroyBorrow(borrow_type& toDestroy) {
    toDestroy.release();
  }

static const owned_type& referenceFromBorrow(const borrow_type& borrow) {
    return borrow;
  }

static const owned_type* pointerFromBorrow(const borrow_type& borrow) {
    return &borrow;
  }

static bool debugBorrowIsValid(const borrow_type& borrow) {
    return true;
  }
};

template <typename T>
struct ExclusivelyOwnedTraits<c10::intrusive_ptr<T>> {
  using repr_type = T*;
  using pointer_type = T*;
  // You can still have non-const access to the T in the const methods
  // because it's not stored by value.
  using const_pointer_type = T*;

static constexpr repr_type nullRepr() {
    return nullptr;
  }

template <class... Args>
  static repr_type createInPlace(Args&&... args) {
    return new T(std::forward<Args>(args)...);
  }

static repr_type moveToRepr(c10::intrusive_ptr<T>&& x) {
    return x.release();
  }

static void destroyOwned(repr_type x) {
    if (!x) {
      return;
    }
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        x->refcount_ == 1,
        "ExclusivelyOwned<intrusive_ptr<T>> destroyed with refcount other than 1!");
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        x->weakcount_ == 1,
        "ExclusivelyOwned<intrusive_ptr<T>> destroyed with weakcount other than 1!");
    const_cast<std::remove_const_t<T>*>(x)->release_resources();
#ifndef NDEBUG
    // Needed to pass the debug assertions in ~intrusive_ptr_target.
    x->refcount_ = 0;
    x->weakcount_ = 0;
#endif
    x->release_resources();
    delete x;
  }

static c10::intrusive_ptr<T> take(repr_type& x) {
    // May need to do reference count initialization, so use the regular
    // intrusive_ptr ctor.

// Refcount would be zero if the ExclusivelyOwned was created
    // in-place (so that the underlying T was never owned by an
    // intrusive_ptr), and it would be 1 if it was created as an
    // intrusive_ptr<T> and then moved into the ExclusivelyOwned.
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        x->refcount_ == 1 || x->refcount_ == 0,
        "take() from ExclusivelyOwned<intrusive_ptr<T>> with refcount other than 0 or 1!");
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        x->weakcount_ == 1 || x->weakcount_ == 0,
        "take() from ExclusivelyOwned<intrusive_ptr<T>> with weakcount other than 0 or 1!");
#ifndef NDEBUG
    // Needed to pass the debug assertions in ~intrusive_ptr_target.
    x->refcount_ = 0;
    x->weakcount_ = 0;
#endif
    auto result = c10::intrusive_ptr<T>(x);
    x = nullptr;
    return result;
  }

static pointer_type getImpl(repr_type x) {
    return x;
  }
};

template <
    typename TTarget,
    class NullType = detail::intrusive_target_default_null_type<TTarget>>
class weak_intrusive_ptr final {
 private:
  static_assert(
      std::is_base_of<intrusive_ptr_target, TTarget>::value,
      "intrusive_ptr can only be used for classes that inherit from intrusive_ptr_target.");
#ifndef _WIN32
  // This static_assert triggers on MSVC
  //  error C2131: expression did not evaluate to a constant
  static_assert(
      NullType::singleton() == NullType::singleton(),
      "NullType must have a constexpr singleton() method");
#endif
  static_assert(
      std::is_base_of<
          TTarget,
          typename std::remove_pointer<decltype(NullType::singleton())>::type>::
          value,
      "NullType::singleton() must return a element_type* pointer");

TTarget* target_;

template <class TTarget2, class NullType2>
  friend class weak_intrusive_ptr;

void retain_() {
    if (target_ != NullType::singleton()) {
      size_t new_weakcount =
          detail::atomic_weakcount_increment(target_->weakcount_);
      TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
          new_weakcount != 1,
          "weak_intrusive_ptr: Cannot increase weakcount after it reached zero.");
    }
  }

void reset_() noexcept {
    if (target_ != NullType::singleton() &&
        detail::atomic_weakcount_decrement(target_->weakcount_) == 0) {
      // NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDelete)
      delete target_;
    }
    target_ = NullType::singleton();
  }

constexpr explicit weak_intrusive_ptr(TTarget* target) : target_(target) {}

public:
  using element_type = TTarget;

explicit weak_intrusive_ptr(const intrusive_ptr<TTarget, NullType>& ptr)
      : weak_intrusive_ptr(ptr.get()) {
    retain_();
  }

weak_intrusive_ptr(weak_intrusive_ptr&& rhs) noexcept : target_(rhs.target_) {
    rhs.target_ = NullType::singleton();
  }

template <class From, class FromNullType>
  /* implicit */ weak_intrusive_ptr(
      weak_intrusive_ptr<From, FromNullType>&& rhs) noexcept
      : target_(
            detail::assign_ptr_<TTarget, NullType, FromNullType>(rhs.target_)) {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. weak_intrusive_ptr move constructor got pointer of wrong type.");
    rhs.target_ = FromNullType::singleton();
  }

weak_intrusive_ptr(const weak_intrusive_ptr& rhs) : target_(rhs.target_) {
    retain_();
  }

template <class From, class FromNullType>
  /* implicit */ weak_intrusive_ptr(
      const weak_intrusive_ptr<From, FromNullType>& rhs)
      : target_(
            detail::assign_ptr_<TTarget, NullType, FromNullType>(rhs.target_)) {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. weak_intrusive_ptr copy constructor got pointer of wrong type.");
    retain_();
  }

~weak_intrusive_ptr() noexcept {
    reset_();
  }

weak_intrusive_ptr& operator=(weak_intrusive_ptr&& rhs) & noexcept {
    return operator=<TTarget, NullType>(std::move(rhs));
  }

template <class From, class FromNullType>
  weak_intrusive_ptr& operator=(
      weak_intrusive_ptr<From, FromNullType>&& rhs) & noexcept {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. weak_intrusive_ptr move assignment got pointer of wrong type.");
    weak_intrusive_ptr tmp = std::move(rhs);
    swap(tmp);
    return *this;
  }

weak_intrusive_ptr& operator=(const weak_intrusive_ptr& rhs) & noexcept {
    return operator=<TTarget, NullType>(rhs);
  }

weak_intrusive_ptr& operator=(
      const intrusive_ptr<TTarget, NullType>& rhs) & noexcept {
    weak_intrusive_ptr tmp(rhs);
    swap(tmp);
    return *this;
  }

template <class From, class FromNullType>
  weak_intrusive_ptr& operator=(
      const weak_intrusive_ptr<From, NullType>& rhs) & {
    static_assert(
        std::is_convertible<From*, TTarget*>::value,
        "Type mismatch. weak_intrusive_ptr copy assignment got pointer of wrong type.");
    weak_intrusive_ptr tmp = rhs;
    swap(tmp);
    return *this;
  }

void reset() noexcept {
    reset_();
  }

void swap(weak_intrusive_ptr& rhs) noexcept {
    TTarget* tmp = target_;
    target_ = rhs.target_;
    rhs.target_ = tmp;
  }

// NB: This should ONLY be used by the std::hash implementation
  // for weak_intrusive_ptr.  Another way you could do this is
  // friend std::hash<weak_intrusive_ptr>, but this triggers two
  // bugs:
  //
  //  (1) It triggers an nvcc bug, where std::hash in a friend class
  //      declaration gets preprocessed into hash, which then cannot
  //      actually be found.  The error in this case looks like:
  //
  //        error: no template named 'hash'; did you mean 'std::hash'?
  //
  //  (2) On OS X, std::hash is declared as a struct, not a class.
  //      This twings:
  //
  //        error: class 'hash' was previously declared as a struct
  //        [-Werror,-Wmismatched-tags]
  //
  // Both of these are work-aroundable, but on the whole, I decided
  // it would be simpler and easier to make work if we just expose
  // an unsafe getter for target_
  //
  TTarget* _unsafe_get_target() const noexcept {
    return target_;
  }

size_t use_count() const noexcept {
    if (target_ == NullType::singleton()) {
      return 0;
    }
    return target_->refcount_.load(
        std::memory_order_acquire); // refcount, not weakcount!
  }

size_t weak_use_count() const noexcept {
    if (target_ == NullType::singleton()) {
      return 0;
    }
    return target_->weakcount_.load(std::memory_order_acquire);
  }

bool expired() const noexcept {
    return use_count() == 0;
  }

intrusive_ptr<TTarget, NullType> lock() const noexcept {
    if (expired()) {
      return intrusive_ptr<TTarget, NullType>();
    } else {
      auto refcount = target_->refcount_.load(std::memory_order_seq_cst);
      do {
        if (refcount == 0) {
          // Object already destructed, no strong references left anymore.
          // Return nullptr.
          return intrusive_ptr<TTarget, NullType>();
        }
      } while (
          !target_->refcount_.compare_exchange_weak(refcount, refcount + 1));
      return intrusive_ptr<TTarget, NullType>(
          target_, raw::DontIncreaseRefcount{});
    }
  }

/**
   * Returns an owning (but still only weakly referenced) pointer to the
   * underlying object and makes the weak_intrusive_ptr instance invalid.
   * That means the weakcount is not decreased.
   * You *must* put the returned pointer back into a weak_intrusive_ptr using
   * weak_intrusive_ptr::reclaim(ptr) to properly destruct it.
   * This is helpful for C APIs.
   */
  TTarget* release() noexcept {
    TTarget* result = target_;
    target_ = NullType::singleton();
    return result;
  }

/**
   * Takes an owning (but must be weakly referenced) pointer to TTarget* and
   * creates a weak_intrusive_ptr that takes over ownership.
   * This means that the weakcount is not increased.
   * This is the counter-part to weak_intrusive_ptr::release() and the pointer
   * passed in *must* have been created using weak_intrusive_ptr::release().
   */
  static weak_intrusive_ptr reclaim(TTarget* owning_weak_ptr) {
    // See Note [Stack allocated intrusive_ptr_target safety]
    // if refcount > 0, weakcount must be >1 for weak references to exist.
    // see weak counting explanation at top of this file.
    // if refcount == 0, weakcount only must be >0.
    TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
        owning_weak_ptr == NullType::singleton() ||
            owning_weak_ptr->weakcount_.load() > 1 ||
            (owning_weak_ptr->refcount_.load() == 0 &&
             owning_weak_ptr->weakcount_.load() > 0),
        "weak_intrusive_ptr: Can only weak_intrusive_ptr::reclaim() owning pointers that were created using weak_intrusive_ptr::release().");
    return weak_intrusive_ptr(owning_weak_ptr);
  }

template <class TTarget1, class NullType1, class TTarget2, class NullType2>
  friend bool operator<(
      const weak_intrusive_ptr<TTarget1, NullType1>& lhs,
      const weak_intrusive_ptr<TTarget2, NullType2>& rhs) noexcept;
  template <class TTarget1, class NullType1, class TTarget2, class NullType2>
  friend bool operator==(
      const weak_intrusive_ptr<TTarget1, NullType1>& lhs,
      const weak_intrusive_ptr<TTarget2, NullType2>& rhs) noexcept;
};

template <class TTarget, class NullType>
inline void swap(
    weak_intrusive_ptr<TTarget, NullType>& lhs,
    weak_intrusive_ptr<TTarget, NullType>& rhs) noexcept {
  lhs.swap(rhs);
}

// To allow weak_intrusive_ptr inside std::map or std::set, we need operator<
template <class TTarget1, class NullType1, class TTarget2, class NullType2>
inline bool operator<(
    const weak_intrusive_ptr<TTarget1, NullType1>& lhs,
    const weak_intrusive_ptr<TTarget2, NullType2>& rhs) noexcept {
  return lhs.target_ < rhs.target_;
}

template <class TTarget1, class NullType1, class TTarget2, class NullType2>
inline bool operator==(
    const weak_intrusive_ptr<TTarget1, NullType1>& lhs,
    const weak_intrusive_ptr<TTarget2, NullType2>& rhs) noexcept {
  return lhs.target_ == rhs.target_;
}

template <class TTarget1, class NullType1, class TTarget2, class NullType2>
inline bool operator!=(
    const weak_intrusive_ptr<TTarget1, NullType1>& lhs,
    const weak_intrusive_ptr<TTarget2, NullType2>& rhs) noexcept {
  return !operator==(lhs, rhs);
}

// Alias for documentary purposes, to more easily distinguish
// weak raw intrusive pointers from intrusive pointers.
using weak_intrusive_ptr_target = intrusive_ptr_target;

// This namespace provides some methods for working with
// raw pointers that subclass intrusive_ptr_target.  They are not provided
// as methods on intrusive_ptr_target, because ideally you would not need these
// methods at all (use smart pointers), but if you are dealing with legacy code
// that still needs to pass around raw pointers, you may find these quite
// useful.
//
// An important usage note: some functions are only valid if you have a
// strong raw pointer to the object, while others are only valid if you
// have a weak raw pointer to the object.  ONLY call intrusive_ptr namespace
// functions on strong pointers, and weak_intrusive_ptr namespace functions
// on weak pointers.  If you mix it up, you may get an assert failure.
namespace raw {

namespace intrusive_ptr {

// WARNING: Unlike the reclaim() API, it is NOT valid to pass
// NullType::singleton to this function
inline void incref(intrusive_ptr_target* self) {
  if (self) {
    detail::atomic_refcount_increment(self->refcount_);
  }
}

// WARNING: Unlike the reclaim() API, it is NOT valid to pass
// NullType::singleton to this function
inline void decref(intrusive_ptr_target* self) {
  // Let it die
  c10::intrusive_ptr<intrusive_ptr_target>::reclaim(self);
  // NB: Caller still has 'self' pointer, but it's now invalid.
  // If you want more safety, used the actual c10::intrusive_ptr class
}

template <typename T>
inline T* make_weak(T* self) {
  // NB: 'this' is a strong pointer, but we return a weak pointer
  auto ptr = c10::intrusive_ptr<T>::reclaim(self);
  c10::weak_intrusive_ptr<T> wptr(ptr);
  ptr.release();
  return wptr.release();
}

inline size_t use_count(intrusive_ptr_target* self) {
  auto ptr = c10::intrusive_ptr<intrusive_ptr_target>::reclaim(self);
  auto r = ptr.use_count();
  ptr.release();
  return r;
}

} // namespace intrusive_ptr

namespace weak_intrusive_ptr {

inline void incref(weak_intrusive_ptr_target* self) {
  detail::atomic_weakcount_increment(self->weakcount_);
}

inline void decref(weak_intrusive_ptr_target* self) {
  // Let it die
  c10::weak_intrusive_ptr<intrusive_ptr_target>::reclaim(self);
  // NB: You still "have" the 'self' pointer, but it's now invalid.
  // If you want more safety, used the actual c10::weak_intrusive_ptr class
}

template <typename T>
inline T* lock(T* self) {
  auto wptr = c10::weak_intrusive_ptr<T>::reclaim(self);
  auto ptr = wptr.lock();
  wptr.release();
  return ptr.release();
}

// This gives the STRONG refcount of a WEAK pointer
inline size_t use_count(weak_intrusive_ptr_target* self) {
  auto wptr = c10::weak_intrusive_ptr<intrusive_ptr_target>::reclaim(self);
  auto r = wptr.use_count();
  wptr.release();
  return r;
}

} // namespace weak_intrusive_ptr

} // namespace raw

} // namespace c10

namespace std {
// To allow intrusive_ptr and weak_intrusive_ptr inside std::unordered_map or
// std::unordered_set, we need std::hash
template <class TTarget, class NullType>
struct hash<c10::intrusive_ptr<TTarget, NullType>> {
  size_t operator()(const c10::intrusive_ptr<TTarget, NullType>& x) const {
    return std::hash<TTarget*>()(x.get());
  }
};
template <class TTarget, class NullType>
struct hash<c10::weak_intrusive_ptr<TTarget, NullType>> {
  size_t operator()(const c10::weak_intrusive_ptr<TTarget, NullType>& x) const {
    return std::hash<TTarget*>()(x._unsafe_get_target());
  }
};
} // namespace std

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