Hi!

This code has src/metric.rs, which unconditionally uses std::sync::atomic::AtomicU64. Quite some platforms don't have 64-bit atomics with current rust, namely it is armel, mipsel, powerpc and x32 (heh). Maybe the metric module can be guarded with the right #[cfg target_has_atomic] ?

Trying to package some stuff for Debian, this crate come as a dependency...

Thanks!