Cross-platform Ruby FFI library

I'm writing FFI ruby wrapper for the google's cityhash library(c++). So, what the best way to make it cross-platform (linux, windows, macos)? Do I nee开发者_高级运维d compile google's library to the shared library during the gem installation? Or just compile it once and ship with gem?

Best would be just checking if this library is installed at all. Treat is as external separate resource!

This way, your users will be able to install updates to the library without giving up your bindings! You do want your users been able to install security updates to this library, right? ;)