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intrusive_ptr.h
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intrusive_ptr.h
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#pragma once
#include <c10/util/C++17.h>
#include <c10/util/Exception.h>
#include <atomic>
#include <stdexcept>
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);
}
}
/**
* 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>.
*/
// 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);
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(
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;
}
}
} // 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_same<TTarget*, decltype(NullType::singleton())>::value,
"NullType::singleton() must return a element_type* pointer");
TTarget* target_;
template <class TTarget2, class NullType2>
friend class intrusive_ptr;
friend class weak_intrusive_ptr<TTarget, NullType>;
void retain_() {
if (target_ != NullType::singleton()) {
size_t new_refcount = ++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() && --target_->refcount_ == 0) {
// justification for const_cast: release_resources is basically a destructor
// and a destructor always mutates the object, even for const objects.
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_ == 0) {
delete target_;
}
}
target_ = NullType::singleton();
}
// This constructor will not increase the ref counter for you.
// This is not public because we shouldn't make intrusive_ptr out of raw
// pointers except from inside the make_intrusive() and
// weak_intrusive_ptr::lock() implementations
explicit intrusive_ptr(TTarget* target) noexcept : target_(target) {}
public:
using element_type = TTarget;
intrusive_ptr() noexcept : intrusive_ptr(NullType::singleton()) {}
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 {
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();
}
size_t weak_use_count() const noexcept {
if (target_ == NullType::singleton()) {
return 0;
}
return target_->weakcount_.load();
}
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 {
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);
}
template <class... Args>
static intrusive_ptr make(Args&&... args) {
auto result = intrusive_ptr(new TTarget(std::forward<Args>(args)...));
// We can't use retain_(), because we also have to increase weakcount
// and because we allow raising these values from 0, which retain_()
// has an assertion against.
++result.target_->refcount_;
++result.target_->weakcount_;
return result;
}
/**
* Turn a **non-owning raw pointer** to an intrusive_ptr.
*
* This method is potentially dangerous (as it can mess up refcount).
*/
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 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_same<TTarget*, decltype(NullType::singleton())>::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 = ++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() && --target_->weakcount_ == 0) {
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);
}
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(); // refcount, not weakcount!
}
size_t weak_use_count() const noexcept {
if (target_ == NullType::singleton()) {
return 0;
}
return target_->weakcount_.load();
}
bool expired() const noexcept {
return use_count() == 0;
}
intrusive_ptr<TTarget, NullType> lock() const noexcept {
auto refcount = target_->refcount_.load();
do {
if (refcount == 0) {
// Object already destructed, no strong references left anymore.
// Return nullptr.
return intrusive_ptr<TTarget, NullType>(NullType::singleton());
}
} while (!target_->refcount_.compare_exchange_weak(refcount, refcount + 1));
return intrusive_ptr<TTarget, NullType>(target_);
}
/**
* 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.
* Thas means 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) {
++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 uint32_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_target
namespace weak_intrusive_ptr {
inline void incref(weak_intrusive_ptr_target* self) {
++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 uint32_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_target
} // 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