#pragma once

struct DeferredInitializer

{

template<typename TFn>

inline static std::shared_ptr<DeferredInitializer> Create(TFn&& fn)

{

HANDLE event = CreateEventW(NULL, TRUE, FALSE, NULL);

struct Data

{

TFn fn;

HANDLE hEvent;

explicit Data(TFn&& fn, HANDLE hEvent)

: fn(std::move(fn)), hEvent(hEvent)

{

}

};

auto data = new Data(std::move(fn), event);

QueueUserWorkItem([](LPVOID arg)

{

auto data = reinterpret_cast<Data*>(arg);

data->fn();

SetEvent(data->hEvent);

delete data;

return DWORD(0);

}, data, 0);

return std::make_shared<DeferredInitializer>(event);

}

inline ~DeferredInitializer()

{

if (event)

{

CloseHandle(event);

event = NULL;

}

}

inline void Wait()

{

if (event)

{

WaitForSingleObject(event, INFINITE);

CloseHandle(event);

event = NULL;

}

}

explicit DeferredInitializer(HANDLE event)

: event(event)

{

}

private:

HANDLE event;

};