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rippled/include/xrpl/basics/IntrusivePointer.ipp

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C++

//------------------------------------------------------------------------------
/*
This file is part of rippled: https://github.com/ripple/rippled
Copyright (c) 2023 Ripple Labs Inc.
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
#ifndef RIPPLE_BASICS_INTRUSIVEPOINTER_IPP_INCLUDED
#define RIPPLE_BASICS_INTRUSIVEPOINTER_IPP_INCLUDED
#include <xrpl/basics/IntrusivePointer.h>
#include <xrpl/basics/IntrusiveRefCounts.h>
#include <utility>
namespace ripple {
template <class T>
template <CAdoptTag TAdoptTag>
SharedIntrusive<T>::SharedIntrusive(T* p, TAdoptTag) noexcept : ptr_{p}
{
if constexpr (std::is_same_v<
TAdoptTag,
SharedIntrusiveAdoptIncrementStrongTag>)
{
if (p)
p->addStrongRef();
}
}
template <class T>
SharedIntrusive<T>::SharedIntrusive(SharedIntrusive const& rhs)
: ptr_{[&] {
auto p = rhs.unsafeGetRawPtr();
if (p)
p->addStrongRef();
return p;
}()}
{
}
template <class T>
template <class TT>
requires std::convertible_to<TT*, T*>
SharedIntrusive<T>::SharedIntrusive(SharedIntrusive<TT> const& rhs)
: ptr_{[&] {
auto p = rhs.unsafeGetRawPtr();
if (p)
p->addStrongRef();
return p;
}()}
{
}
template <class T>
SharedIntrusive<T>::SharedIntrusive(SharedIntrusive&& rhs)
: ptr_{rhs.unsafeExchange(nullptr)}
{
}
template <class T>
template <class TT>
requires std::convertible_to<TT*, T*>
SharedIntrusive<T>::SharedIntrusive(SharedIntrusive<TT>&& rhs)
: ptr_{rhs.unsafeExchange(nullptr)}
{
}
template <class T>
SharedIntrusive<T>&
SharedIntrusive<T>::operator=(SharedIntrusive const& rhs)
{
if (this == &rhs)
return *this;
auto p = rhs.unsafeGetRawPtr();
if (p)
p->addStrongRef();
unsafeReleaseAndStore(p);
return *this;
}
template <class T>
template <class TT>
// clang-format off
requires std::convertible_to<TT*, T*>
// clang-format on
SharedIntrusive<T>&
SharedIntrusive<T>::operator=(SharedIntrusive<TT> const& rhs)
{
if constexpr (std::is_same_v<T, TT>)
{
// This case should never be hit. The operator above will run instead.
// (The normal operator= is needed or it will be marked `deleted`)
if (this == &rhs)
return *this;
}
auto p = rhs.unsafeGetRawPtr();
if (p)
p->addStrongRef();
unsafeReleaseAndStore(p);
return *this;
}
template <class T>
SharedIntrusive<T>&
SharedIntrusive<T>::operator=(SharedIntrusive&& rhs)
{
if (this == &rhs)
return *this;
unsafeReleaseAndStore(rhs.unsafeExchange(nullptr));
return *this;
}
template <class T>
template <class TT>
// clang-format off
requires std::convertible_to<TT*, T*>
// clang-format on
SharedIntrusive<T>&
SharedIntrusive<T>::operator=(SharedIntrusive<TT>&& rhs)
{
static_assert(
!std::is_same_v<T, TT>,
"This overload should not be instantiated for T == TT");
unsafeReleaseAndStore(rhs.unsafeExchange(nullptr));
return *this;
}
template <class T>
bool
SharedIntrusive<T>::operator!=(std::nullptr_t) const
{
return this->get() != nullptr;
}
template <class T>
bool
SharedIntrusive<T>::operator==(std::nullptr_t) const
{
return this->get() == nullptr;
}
template <class T>
template <CAdoptTag TAdoptTag>
void
SharedIntrusive<T>::adopt(T* p)
{
if constexpr (std::is_same_v<
TAdoptTag,
SharedIntrusiveAdoptIncrementStrongTag>)
{
if (p)
p->addStrongRef();
}
unsafeReleaseAndStore(p);
}
template <class T>
SharedIntrusive<T>::~SharedIntrusive()
{
unsafeReleaseAndStore(nullptr);
};
template <class T>
template <class TT>
SharedIntrusive<T>::SharedIntrusive(
StaticCastTagSharedIntrusive,
SharedIntrusive<TT> const& rhs)
: ptr_{[&] {
auto p = static_cast<T*>(rhs.unsafeGetRawPtr());
if (p)
p->addStrongRef();
return p;
}()}
{
}
template <class T>
template <class TT>
SharedIntrusive<T>::SharedIntrusive(
StaticCastTagSharedIntrusive,
SharedIntrusive<TT>&& rhs)
: ptr_{static_cast<T*>(rhs.unsafeExchange(nullptr))}
{
}
template <class T>
template <class TT>
SharedIntrusive<T>::SharedIntrusive(
DynamicCastTagSharedIntrusive,
SharedIntrusive<TT> const& rhs)
: ptr_{[&] {
auto p = dynamic_cast<T*>(rhs.unsafeGetRawPtr());
if (p)
p->addStrongRef();
return p;
}()}
{
}
template <class T>
template <class TT>
SharedIntrusive<T>::SharedIntrusive(
DynamicCastTagSharedIntrusive,
SharedIntrusive<TT>&& rhs)
{
// This can be simplified without the `exchange`, but the `exchange` is kept
// in anticipation of supporting atomic operations.
auto toSet = rhs.unsafeExchange(nullptr);
if (toSet)
{
ptr_ = dynamic_cast<T*>(toSet);
if (!ptr_)
// need to set the pointer back or will leak
rhs.unsafeExchange(toSet);
}
}
template <class T>
T&
SharedIntrusive<T>::operator*() const noexcept
{
return *unsafeGetRawPtr();
}
template <class T>
T*
SharedIntrusive<T>::operator->() const noexcept
{
return unsafeGetRawPtr();
}
template <class T>
SharedIntrusive<T>::operator bool() const noexcept
{
return bool(unsafeGetRawPtr());
}
template <class T>
void
SharedIntrusive<T>::reset()
{
unsafeReleaseAndStore(nullptr);
}
template <class T>
T*
SharedIntrusive<T>::get() const
{
return unsafeGetRawPtr();
}
template <class T>
std::size_t
SharedIntrusive<T>::use_count() const
{
if (auto p = unsafeGetRawPtr())
return p->use_count();
return 0;
}
template <class T>
T*
SharedIntrusive<T>::unsafeGetRawPtr() const
{
return ptr_;
}
template <class T>
void
SharedIntrusive<T>::unsafeSetRawPtr(T* p)
{
ptr_ = p;
}
template <class T>
T*
SharedIntrusive<T>::unsafeExchange(T* p)
{
return std::exchange(ptr_, p);
}
template <class T>
void
SharedIntrusive<T>::unsafeReleaseAndStore(T* next)
{
auto prev = unsafeExchange(next);
if (!prev)
return;
using enum ReleaseStrongRefAction;
auto action = prev->releaseStrongRef();
switch (action)
{
case noop:
break;
case destroy:
delete prev;
break;
case partialDestroy:
prev->partialDestructor();
partialDestructorFinished(&prev);
// prev is null and may no longer be used
break;
}
}
//------------------------------------------------------------------------------
template <class T>
WeakIntrusive<T>::WeakIntrusive(WeakIntrusive const& rhs) : ptr_{rhs.ptr_}
{
if (ptr_)
ptr_->addWeakRef();
}
template <class T>
WeakIntrusive<T>::WeakIntrusive(WeakIntrusive&& rhs) : ptr_{rhs.ptr_}
{
rhs.ptr_ = nullptr;
}
template <class T>
WeakIntrusive<T>::WeakIntrusive(SharedIntrusive<T> const& rhs)
: ptr_{rhs.unsafeGetRawPtr()}
{
if (ptr_)
ptr_->addWeakRef();
}
template <class T>
template <class TT>
// clang-format off
requires std::convertible_to<TT*, T*>
// clang-format on
WeakIntrusive<T>&
WeakIntrusive<T>::operator=(SharedIntrusive<TT> const& rhs)
{
unsafeReleaseNoStore();
auto p = rhs.unsafeGetRawPtr();
if (p)
p->addWeakRef();
return *this;
}
template <class T>
void
WeakIntrusive<T>::adopt(T* ptr)
{
unsafeReleaseNoStore();
if (ptr)
ptr->addWeakRef();
ptr_ = ptr;
}
template <class T>
WeakIntrusive<T>::~WeakIntrusive()
{
unsafeReleaseNoStore();
}
template <class T>
SharedIntrusive<T>
WeakIntrusive<T>::lock() const
{
if (ptr_ && ptr_->checkoutStrongRefFromWeak())
{
return SharedIntrusive<T>{ptr_, SharedIntrusiveAdoptNoIncrementTag{}};
}
return {};
}
template <class T>
bool
WeakIntrusive<T>::expired() const
{
return (!ptr_ || ptr_->expired());
}
template <class T>
void
WeakIntrusive<T>::reset()
{
unsafeReleaseNoStore();
ptr_ = nullptr;
}
template <class T>
void
WeakIntrusive<T>::unsafeReleaseNoStore()
{
if (!ptr_)
return;
using enum ReleaseWeakRefAction;
auto action = ptr_->releaseWeakRef();
switch (action)
{
case noop:
break;
case destroy:
delete ptr_;
break;
}
}
//------------------------------------------------------------------------------
template <class T>
SharedWeakUnion<T>::SharedWeakUnion(SharedWeakUnion const& rhs) : tp_{rhs.tp_}
{
auto p = rhs.unsafeGetRawPtr();
if (!p)
return;
if (rhs.isStrong())
p->addStrongRef();
else
p->addWeakRef();
}
template <class T>
template <class TT>
requires std::convertible_to<TT*, T*>
SharedWeakUnion<T>::SharedWeakUnion(SharedIntrusive<TT> const& rhs)
{
auto p = rhs.unsafeGetRawPtr();
if (p)
p->addStrongRef();
unsafeSetRawPtr(p, RefStrength::strong);
}
template <class T>
SharedWeakUnion<T>::SharedWeakUnion(SharedWeakUnion&& rhs) : tp_{rhs.tp_}
{
rhs.unsafeSetRawPtr(nullptr);
}
template <class T>
template <class TT>
requires std::convertible_to<TT*, T*>
SharedWeakUnion<T>::SharedWeakUnion(SharedIntrusive<TT>&& rhs)
{
auto p = rhs.unsafeGetRawPtr();
if (p)
unsafeSetRawPtr(p, RefStrength::strong);
rhs.unsafeSetRawPtr(nullptr);
}
template <class T>
SharedWeakUnion<T>&
SharedWeakUnion<T>::operator=(SharedWeakUnion const& rhs)
{
if (this == &rhs)
return *this;
unsafeReleaseNoStore();
if (auto p = rhs.unsafeGetRawPtr())
{
if (rhs.isStrong())
{
p->addStrongRef();
unsafeSetRawPtr(p, RefStrength::strong);
}
else
{
p->addWeakRef();
unsafeSetRawPtr(p, RefStrength::weak);
}
}
else
{
unsafeSetRawPtr(nullptr);
}
return *this;
}
template <class T>
template <class TT>
// clang-format off
requires std::convertible_to<TT*, T*>
// clang-format on
SharedWeakUnion<T>&
SharedWeakUnion<T>::operator=(SharedIntrusive<TT> const& rhs)
{
unsafeReleaseNoStore();
auto p = rhs.unsafeGetRawPtr();
if (p)
p->addStrongRef();
unsafeSetRawPtr(p, RefStrength::strong);
return *this;
}
template <class T>
template <class TT>
// clang-format off
requires std::convertible_to<TT*, T*>
// clang-format on
SharedWeakUnion<T>&
SharedWeakUnion<T>::operator=(SharedIntrusive<TT>&& rhs)
{
unsafeReleaseNoStore();
unsafeSetRawPtr(rhs.unsafeGetRawPtr(), RefStrength::strong);
rhs.unsafeSetRawPtr(nullptr);
return *this;
}
template <class T>
SharedWeakUnion<T>::~SharedWeakUnion()
{
unsafeReleaseNoStore();
};
// Return a strong pointer if this is already a strong pointer (i.e. don't
// lock the weak pointer. Use the `lock` method if that's what's needed)
template <class T>
SharedIntrusive<T>
SharedWeakUnion<T>::getStrong() const
{
SharedIntrusive<T> result;
auto p = unsafeGetRawPtr();
if (p && isStrong())
{
result.template adopt<SharedIntrusiveAdoptIncrementStrongTag>(p);
}
return result;
}
template <class T>
SharedWeakUnion<T>::operator bool() const noexcept
{
return bool(get());
}
template <class T>
void
SharedWeakUnion<T>::reset()
{
unsafeReleaseNoStore();
unsafeSetRawPtr(nullptr);
}
template <class T>
T*
SharedWeakUnion<T>::get() const
{
return isStrong() ? unsafeGetRawPtr() : nullptr;
}
template <class T>
std::size_t
SharedWeakUnion<T>::use_count() const
{
if (auto p = get())
return p->use_count();
return 0;
}
template <class T>
bool
SharedWeakUnion<T>::expired() const
{
auto p = unsafeGetRawPtr();
return (!p || p->expired());
}
template <class T>
SharedIntrusive<T>
SharedWeakUnion<T>::lock() const
{
SharedIntrusive<T> result;
auto p = unsafeGetRawPtr();
if (!p)
return result;
if (isStrong())
{
result.template adopt<SharedIntrusiveAdoptIncrementStrongTag>(p);
return result;
}
if (p->checkoutStrongRefFromWeak())
{
result.template adopt<SharedIntrusiveAdoptNoIncrementTag>(p);
return result;
}
return result;
}
template <class T>
bool
SharedWeakUnion<T>::isStrong() const
{
return !(tp_ & tagMask);
}
template <class T>
bool
SharedWeakUnion<T>::isWeak() const
{
return tp_ & tagMask;
}
template <class T>
bool
SharedWeakUnion<T>::convertToStrong()
{
if (isStrong())
return true;
auto p = unsafeGetRawPtr();
if (p && p->checkoutStrongRefFromWeak())
{
[[maybe_unused]] auto action = p->releaseWeakRef();
XRPL_ASSERT(
(action == ReleaseWeakRefAction::noop),
"ripple::SharedWeakUnion::convertToStrong : "
"action is noop");
unsafeSetRawPtr(p, RefStrength::strong);
return true;
}
return false;
}
template <class T>
bool
SharedWeakUnion<T>::convertToWeak()
{
if (isWeak())
return true;
auto p = unsafeGetRawPtr();
if (!p)
return false;
using enum ReleaseStrongRefAction;
auto action = p->addWeakReleaseStrongRef();
switch (action)
{
case noop:
break;
case destroy:
// We just added a weak ref. How could we destroy?
// LCOV_EXCL_START
UNREACHABLE(
"ripple::SharedWeakUnion::convertToWeak : destroying freshly "
"added ref");
delete p;
unsafeSetRawPtr(nullptr);
return true; // Should never happen
// LCOV_EXCL_STOP
case partialDestroy:
// This is a weird case. We just converted the last strong
// pointer to a weak pointer.
p->partialDestructor();
partialDestructorFinished(&p);
// p is null and may no longer be used
break;
}
unsafeSetRawPtr(p, RefStrength::weak);
return true;
}
template <class T>
T*
SharedWeakUnion<T>::unsafeGetRawPtr() const
{
return reinterpret_cast<T*>(tp_ & ptrMask);
}
template <class T>
void
SharedWeakUnion<T>::unsafeSetRawPtr(T* p, RefStrength rs)
{
tp_ = reinterpret_cast<std::uintptr_t>(p);
if (tp_ && rs == RefStrength::weak)
tp_ |= tagMask;
}
template <class T>
void
SharedWeakUnion<T>::unsafeSetRawPtr(std::nullptr_t)
{
tp_ = 0;
}
template <class T>
void
SharedWeakUnion<T>::unsafeReleaseNoStore()
{
auto p = unsafeGetRawPtr();
if (!p)
return;
if (isStrong())
{
using enum ReleaseStrongRefAction;
auto strongAction = p->releaseStrongRef();
switch (strongAction)
{
case noop:
break;
case destroy:
delete p;
break;
case partialDestroy:
p->partialDestructor();
partialDestructorFinished(&p);
// p is null and may no longer be used
break;
}
}
else
{
using enum ReleaseWeakRefAction;
auto weakAction = p->releaseWeakRef();
switch (weakAction)
{
case noop:
break;
case destroy:
delete p;
break;
}
}
}
} // namespace ripple
#endif