benchmark-macro.rs

/*
If you look, I've also included a pattern to pass the number of times you want 
the benchmark to run. I default to ten runs instead of one-hundred here as code 
under inspection may take a long time to run under one-hundred times. You will 
notice that I'm using nanoseconds for everything, which lets me compute a 
proper mean average without rounding.
*/
macro_rules! bench {
    ($val:expr) => {
        {
            let mut mean = 0;
            let times = 10;
            for _ in 0..times {
                let beg = std::time::Instant::now();
                match $val {
                    _ => {
                        let end = std::time::Instant::now();
                        mean += (end - beg).as_nanos();
                    }
                } 
            }
            mean /= times;
            eprintln!("[{}:{}] `{}' took {} ns after {} runs", std::file!(), std::line!(), std::stringify!($val), mean, times);
            $val
        }
    };
    ($val:expr, $times:expr) => {
        {
            let mut mean = 0;
            for _ in 0..$times {
                let beg = std::time::Instant::now();
                match $val {
                    _ => {
                        let end = std::time::Instant::now();
                        mean += (end - beg).as_nanos();
                    }
                } 
            }
            mean /= $times;
            eprintln!("[{}:{}] `{}' took {} ns after {} runs", std::file!(), std::line!(), std::stringify!($val), mean, $times);
            $val
        }
    };
    ($($val:expr),+ $(,)?) => {
        ($(bench!($val)),+,)
    };    
}