Can clear a specific factory from static lifetime store (#654)

Author: oldnewthing

strings/base_abi.h

@@ -70,8 +70,8 @@ namespace winrt::impl
         virtual int32_t __stdcall unused2() noexcept = 0;
         virtual int32_t __stdcall unused3() noexcept = 0;
         virtual int32_t __stdcall Insert(void*, void*, bool*) noexcept = 0;
+        virtual int32_t __stdcall Remove(void*) noexcept = 0;
         virtual int32_t __stdcall unused4() noexcept = 0;
-        virtual int32_t __stdcall unused5() noexcept = 0;
     };
 
     struct __declspec(novtable) IWeakReference : unknown_abi

strings/base_implements.h

@@ -1198,6 +1198,14 @@ namespace winrt::impl
     };
 #endif
 
+    inline com_ptr<IStaticLifetimeCollection> get_static_lifetime_map()
+    {
+        auto const lifetime_factory = get_activation_factory<impl::IStaticLifetime>(L"Windows.ApplicationModel.Core.CoreApplication");
+        Windows::Foundation::IUnknown collection;
+        check_hresult(lifetime_factory->GetCollection(put_abi(collection)));
+        return collection.as<IStaticLifetimeCollection>();
+    }
+
     template <typename D>
     auto make_factory() -> typename impl::implements_default_interface<D>::type
     {
@@ -1209,10 +1217,7 @@ namespace winrt::impl
         }
         else
         {
-            auto const lifetime_factory = get_activation_factory<impl::IStaticLifetime>(L"Windows.ApplicationModel.Core.CoreApplication");
-            Windows::Foundation::IUnknown collection;
-            check_hresult(lifetime_factory->GetCollection(put_abi(collection)));
-            auto const map = collection.as<IStaticLifetimeCollection>();
+            auto const map = get_static_lifetime_map();
             param::hstring const name{ name_of<typename D::instance_type>() };
             void* result{};
             map->Lookup(get_abi(name), &result);
@@ -1304,6 +1309,16 @@ WINRT_EXPORT namespace winrt
         }
     }
 
+    template <typename... FactoryClasses>
+    inline void clear_factory_static_lifetime()
+    {
+        auto unregister = [map = impl::get_static_lifetime_map()](param::hstring name)
+        {
+            map->Remove(get_abi(name));
+        };
+        ((unregister(name_of<typename FactoryClasses::instance_type>())), ...);
+    }
+
     template <typename D, typename... I>
     struct implements : impl::producers<D, I...>, impl::base_implements<D, I...>::type
     {

test/old_tests/Component/Events.cpp

@@ -74,25 +74,51 @@ namespace winrt::Component::factory_implementation
 
     bool Events::TestStaticLifetime()
     {
+        auto GetReferenceCount = [this]()
+        {
+            AddRef();
+            return Release();
+        };
+
         // Capture current reference count.
-        AddRef();
-        auto refcount = Release();
+        auto refcount = GetReferenceCount();
 
         // Reset constructor count.
         s_constructorCount = 0;
 
-        auto self = make_self<Events>();
-        if (self.get() != this)
+        // make_self should return a reference to ourselves
+        // since we are static_lifetime.
+        if (make_self<Events>().get() != this)
         {
             return false;
         }
-        self = nullptr;
 
         // Refcount should be unchanged.
+        if (refcount != GetReferenceCount())
+        {
+            return false;
+        }
+
         // Should not have been constructed spuriously.
-        AddRef();
-        auto new_refcount = Release();
+        if (s_constructorCount != 0)
+        {
+            return false;
+        }
+
+        // Clear the static lifetime. That should drop the reference count.
+        clear_factory_static_lifetime<Events>();
+        if (refcount == GetReferenceCount())
+        {
+            return false;
+        }
+
+        // Making a new object should put a different instance into
+        // the static lifetime.
+        if (make_self<Events>().get() == this)
+        {
+            return false;
+        }
 
-        return refcount == new_refcount && s_constructorCount == 0;
+        return true;
     }
 }