Optimize factory caching for apps and pinned DLLs (#1031)

Author: kennykerr

strings/base_activation.h

@@ -233,19 +233,23 @@ namespace winrt::impl
 
         explicit factory_count_guard(size_t& count) noexcept : m_count(count)
         {
+#ifndef WINRT_NO_MODULE_LOCK
 #ifdef _WIN64
             _InterlockedIncrement64((int64_t*)&m_count);
 #else
             _InterlockedIncrement((long*)&m_count);
+#endif
 #endif
         }
 
         ~factory_count_guard() noexcept
         {
+#ifndef WINRT_NO_MODULE_LOCK
 #ifdef _WIN64
             _InterlockedDecrement64((int64_t*)&m_count);
 #else
             _InterlockedDecrement((long*)&m_count);
+#endif
 #endif
         }
 
@@ -362,7 +366,9 @@ namespace winrt::impl
                 if (nullptr == _InterlockedCompareExchangePointer(reinterpret_cast<void**>(&m_value.object), *reinterpret_cast<void**>(&object), nullptr))
                 {
                     *reinterpret_cast<void**>(&object) = nullptr;
+#ifndef WINRT_NO_MODULE_LOCK
                     get_factory_cache().add(this);
+#endif
                 }
 
                 return callback(*reinterpret_cast<com_ref<Interface> const*>(&m_value.object));

test/test_module_lock_none/main.cpp

@@ -6,6 +6,7 @@
 
 #define WINRT_NO_MODULE_LOCK
 #include "winrt/Windows.Foundation.h"
+#include "winrt/Windows.System.Diagnostics.h"
 
 namespace
 {
@@ -26,9 +27,31 @@ TEST_CASE("module_lock_none")
     REQUIRE(--winrt::get_module_lock() == 0);
     REQUIRE(--winrt::get_module_lock() == 0);
 
-    // Just validates that you can still construct an implementation without a module lock.
+    // Validates that you can still construct an implementation without a module lock.
 
     winrt::make<FastStringable>();
+
+    // Validates that clear_factory_cache is still callable, but has no effect.
+    // Windows.System.Diagnostics is used because it is implemented in C++/WinRT that
+    // unlike WRL, does not cache factories inside the implementation. Client-side
+    // caching is far more effective.
+
+    void* first = nullptr;
+    void* second = nullptr;
+
+    {
+        auto factory = winrt::get_activation_factory<winrt::Windows::System::Diagnostics::SystemDiagnosticInfo>();
+        first = winrt::get_abi(factory);
+    }
+    winrt::clear_factory_cache();
+
+    {
+        auto factory = winrt::get_activation_factory<winrt::Windows::System::Diagnostics::SystemDiagnosticInfo>();
+        second = winrt::get_abi(factory);
+    }
+    winrt::clear_factory_cache();
+
+    REQUIRE(first == second);
 }
 
 int main(int const argc, char** argv)