need help to use C++ callback from garnet

[Dakota]

I try use 
https://github.com/microsoft/garnet/blob/main/libs/storage/Tsavorite/cc/src/device/native_device_wrapper.cc from D


Not sure how to make this work with D:

```c++
	EXPORTED_SYMBOL FASTER::core::Status 
NativeDevice_ReadAsync(NativeDevice* device, uint64_t source, 
void* dest, uint32_t length, FASTER::core::AsyncIOCallback 
callback, void* context) {
		return device->ReadAsync(source, dest, length, callback, 
context);
	}

	EXPORTED_SYMBOL FASTER::core::Status 
NativeDevice_WriteAsync(NativeDevice* device, const void* source, 
uint64_t dest, uint32_t length, FASTER::core::AsyncIOCallback 
callback, void* context) {
		return device->WriteAsync(source, dest, length, callback, 
context);
	}
```

I need to define `FASTER::core::AsyncIOCallback callback` from D, 
any way to workaround ? (like modify garnet source code to 
support pass a C function callback)

I am newbie to C++ and D, any help will be appreciate