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Merged
kennykerr merged 2 commits into from
Apr 21, 2020
Merged

Weak references are objects too #599

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88b5560
Weak references are objects too
oldnewthing Apr 21, 2020
52b17a8
Merge branch 'master' into weak_refcount
kennykerr Apr 21, 2020
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26 changes: 23 additions & 3 deletions strings/base_agile_ref.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,19 +44,39 @@ WINRT_EXPORT namespace winrt

namespace winrt::impl
{
struct agile_ref_fallback final : IAgileReference
template<bool UseModuleLock>
struct module_lock_updater;

template<>
struct module_lock_updater<true>
{
module_lock_updater() noexcept
{
++get_module_lock();
}

~module_lock_updater() noexcept
{
--get_module_lock();
}
};

template<>
struct module_lock_updater<false> {};

using update_module_lock = module_lock_updater<true>;

struct agile_ref_fallback final : IAgileReference, update_module_lock
{
agile_ref_fallback(com_ptr<IGlobalInterfaceTable>&& git, uint32_t cookie) noexcept :
m_git(std::move(git)),
m_cookie(cookie)
{
++get_module_lock();
}

~agile_ref_fallback() noexcept
{
m_git->RevokeInterfaceFromGlobal(m_cookie);
--get_module_lock();
}

int32_t __stdcall QueryInterface(guid const& id, void** object) noexcept final
Expand Down
16 changes: 2 additions & 14 deletions strings/base_delegate.h
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Expand Up @@ -2,16 +2,10 @@
namespace winrt::impl
{
template <typename T, typename H>
struct implements_delegate : abi_t<T>, H
struct implements_delegate : abi_t<T>, H, update_module_lock
{
implements_delegate(H&& handler) : H(std::forward<H>(handler))
{
++get_module_lock();
}

~implements_delegate() noexcept
{
--get_module_lock();
}

int32_t __stdcall QueryInterface(guid const& id, void** result) noexcept final
Expand Down Expand Up @@ -98,16 +92,10 @@ namespace winrt::impl
};

template <typename H, typename R, typename... Args>
struct variadic_delegate final : variadic_delegate_abi<R, Args...>, H
struct variadic_delegate final : variadic_delegate_abi<R, Args...>, H, update_module_lock
{
variadic_delegate(H&& handler) : H(std::forward<H>(handler))
{
++get_module_lock();
}

~variadic_delegate() noexcept
{
--get_module_lock();
}

R invoke(Args const& ... args) final
Expand Down
8 changes: 1 addition & 7 deletions strings/base_error.h
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Expand Up @@ -56,18 +56,12 @@ namespace winrt::impl
return ((int32_t)((x) | 0x10000000));
}

struct error_info_fallback final : IErrorInfo, IRestrictedErrorInfo
struct error_info_fallback final : IErrorInfo, IRestrictedErrorInfo, update_module_lock
{
error_info_fallback(int32_t code, void* message) noexcept :
m_code(code),
m_message(*reinterpret_cast<winrt::hstring*>(&message))
{
++get_module_lock();
}

~error_info_fallback() noexcept
{
--get_module_lock();
}

int32_t __stdcall QueryInterface(guid const& id, void** object) noexcept final
Expand Down
36 changes: 14 additions & 22 deletions strings/base_implements.h
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Expand Up @@ -522,18 +522,18 @@ namespace winrt::impl
}
};

template <bool Agile>
template <bool Agile, bool UseModuleLock>
struct weak_ref;

template <bool Agile>
template <bool Agile, bool UseModuleLock>
struct weak_source_producer;

template <bool Agile>
struct weak_source final : IWeakReferenceSource
template <bool Agile, bool UseModuleLock>
struct weak_source final : IWeakReferenceSource, module_lock_updater<UseModuleLock>
{
weak_ref<Agile>* that() noexcept
weak_ref<Agile, UseModuleLock>* that() noexcept
{
return static_cast<weak_ref<Agile>*>(reinterpret_cast<weak_source_producer<Agile>*>(this));
return static_cast<weak_ref<Agile, UseModuleLock>*>(reinterpret_cast<weak_source_producer<Agile, UseModuleLock>*>(this));
}

int32_t __stdcall QueryInterface(guid const& id, void** object) noexcept final
Expand Down Expand Up @@ -566,15 +566,15 @@ namespace winrt::impl
}
};

template <bool Agile>
template <bool Agile, bool UseModuleLock>
struct weak_source_producer
{
protected:
weak_source<Agile> m_source;
weak_source<Agile, UseModuleLock> m_source;
};

template <bool Agile>
struct weak_ref final : IWeakReference, weak_source_producer<Agile>
template <bool Agile, bool UseModuleLock>
struct weak_ref final : IWeakReference, weak_source_producer<Agile, UseModuleLock>
{
weak_ref(unknown_abi* object, uint32_t const strong) noexcept :
m_object(object),
Expand Down Expand Up @@ -678,10 +678,10 @@ namespace winrt::impl
}

private:
template <bool T>
template <bool T, bool U>
friend struct weak_source;

static_assert(sizeof(weak_source_producer<Agile>) == sizeof(weak_source<Agile>));
static_assert(sizeof(weak_source_producer<Agile, UseModuleLock>) == sizeof(weak_source<Agile, UseModuleLock>));

unknown_abi* m_object{};
std::atomic<uint32_t> m_strong{ 1 };
Expand Down Expand Up @@ -743,6 +743,7 @@ namespace winrt::impl
struct __declspec(novtable) root_implements
: root_implements_composing_outer<std::disjunction_v<std::is_same<composing, I>...>>
, root_implements_composable_inner<D, std::disjunction_v<std::is_same<composable, I>...>>
, module_lock_updater<!std::disjunction_v<std::is_same<no_module_lock, I>...>>
{
using IInspectable = Windows::Foundation::IInspectable;
using root_implements_type = root_implements;
Expand Down Expand Up @@ -819,21 +820,12 @@ namespace winrt::impl

root_implements() noexcept
{
if constexpr (use_module_lock::value)
{
++get_module_lock();
}
}

virtual ~root_implements() noexcept
{
// If a weak reference is created during destruction, this ensures that it is also destroyed.
subtract_reference();

if constexpr (use_module_lock::value)
{
--get_module_lock();
}
}

int32_t __stdcall GetIids(uint32_t* count, guid** array) noexcept
Expand Down Expand Up @@ -1060,7 +1052,7 @@ namespace winrt::impl
using is_inspectable = std::disjunction<std::is_base_of<Windows::Foundation::IInspectable, I>...>;
using is_weak_ref_source = std::conjunction<is_inspectable, std::negation<is_factory>, std::negation<std::disjunction<std::is_same<no_weak_ref, I>...>>>;
using use_module_lock = std::negation<std::disjunction<std::is_same<no_module_lock, I>...>>;
using weak_ref_t = impl::weak_ref<is_agile::value>;
using weak_ref_t = impl::weak_ref<is_agile::value, use_module_lock::value>;

std::atomic<std::conditional_t<is_weak_ref_source::value, uintptr_t, uint32_t>> m_references{ 1 };

Expand Down
40 changes: 40 additions & 0 deletions test/old_tests/UnitTests/weak.cpp
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Expand Up @@ -41,6 +41,14 @@ namespace
return L"NoWeakRef";
}
};

struct WeakNoModuleLock : implements<WeakNoModuleLock, IStringable, no_module_lock>
{
hstring ToString()
{
return L"WeakNoModuleLock";
}
};
}

TEST_CASE("weak,source")
Expand Down Expand Up @@ -268,3 +276,35 @@ TEST_CASE("weak,lifetime")
REQUIRE(!ref.try_as<IAgileObject>());
}
}

TEST_CASE("weak,module_lock")
{
uint32_t object_count = get_module_lock();

IStringable a = make<Weak>();

// Strong reference counts as an object.
REQUIRE(get_module_lock() == object_count + 1);

weak_ref<IStringable> w = a;
a = nullptr;

// Weak reference should still count as an object.
REQUIRE(get_module_lock() == object_count + 1);
}

TEST_CASE("weak,no_module_lock")
{
uint32_t object_count = get_module_lock();

IStringable a = make<WeakNoModuleLock>();

REQUIRE(get_module_lock() == object_count);

weak_ref<IStringable> w = a;
a = nullptr;

// Weak reference to no-module-lock object is also no-module-lock.
REQUIRE(get_module_lock() == object_count);
}