source: benchmark/readyQ/yield.rs@ e5aba4a

use std::sync::Arc;
use std::sync::atomic::Ordering;
use std::time::Instant;

use tokio::runtime::Builder;
use tokio::sync;
use tokio::task;

use clap::App;
use num_format::{Locale, ToFormattedString};

#[path = "../bench.rs"]
mod bench;

// ==================================================
struct Yielder {
        sem: sync::Semaphore,
}

async fn yield_main(idx: usize, others: Arc<Vec<Arc<Yielder>>>, exp: Arc<bench::BenchData> ) -> u64 {
        let this = &others[idx];
        this.sem.acquire().await.forget();

        let mut count:u64 = 0;
        loop {
                task::yield_now().await;
                count += 1;

                if  exp.clock_mode && exp.stop.load(Ordering::Relaxed) { break; }
                if !exp.clock_mode && count >= exp.stop_count { break; }
        }

        exp.threads_left.fetch_sub(1, Ordering::SeqCst);
        count
}

// ==================================================
fn main() {
        let options = App::new("Cycle Tokio")
                .args(&bench::args())
                .get_matches();

        let nthreads  = options.value_of("nthreads").unwrap().parse::<usize>().unwrap();
        let nprocs    = options.value_of("nprocs").unwrap().parse::<usize>().unwrap();

        let exp = Arc::new(bench::BenchData::new(options, nthreads));

        let s = (1000000 as u64).to_formatted_string(&Locale::en);
        assert_eq!(&s, "1,000,000");

        let thddata : Arc<Vec<Arc<Yielder>>> = Arc::new(
                (0..nthreads).map(|i| {
                        let pi = (i + nthreads) % nthreads;
                        Arc::new(Yielder{
                                sem: sync::Semaphore::new(0),
                        })
                }).collect()
        );

        let mut global_counter :u64 = 0;
        let mut duration : std::time::Duration = std::time::Duration::from_secs(0);
        let runtime = Builder::new_multi_thread()
                .worker_threads(nprocs)
                .enable_all()
                .build()
                .unwrap();

        runtime.block_on(async {
                let threads: Vec<_> = (0..nthreads).map(|i| {
                        tokio::spawn(yield_main(i, thddata.clone(), exp.clone()))
                }).collect();
                println!("Starting");

                let start = Instant::now();

                for i in 0..nthreads {
                        thddata[i].sem.add_permits(1);
                }

                duration = exp.wait(&start).await;

                println!("\nDone");

                for i in 0..nthreads {
                        thddata[i].sem.add_permits(1);
                }

                for t in threads {
                        global_counter += t.await.unwrap();
                }
        });

        println!("Duration (ms)       : {}", (duration.as_millis()).to_formatted_string(&Locale::en));
        println!("Number of processors: {}", (nprocs).to_formatted_string(&Locale::en));
        println!("Number of threads   : {}", (nthreads).to_formatted_string(&Locale::en));
        println!("Total yields        : {:>15}", (global_counter).to_formatted_string(&Locale::en));
        println!("Yields per second   : {:>15}", (((global_counter as f64) / duration.as_secs() as f64) as u64).to_formatted_string(&Locale::en));
        println!("ns per yields       : {:>15}", ((duration.as_nanos() as f64 / global_counter as f64) as u64).to_formatted_string(&Locale::en));
        println!("Yields per threads  : {:>15}", (global_counter / nthreads as u64).to_formatted_string(&Locale::en));
        println!("Yields per procs    : {:>15}", (global_counter / nprocs as u64).to_formatted_string(&Locale::en));
        println!("Yields/sec/procs    : {:>15}", ((((global_counter as f64) / nprocs as f64) / duration.as_secs() as f64) as u64).to_formatted_string(&Locale::en));
        println!("ns per yields/procs : {:>15}", ((duration.as_nanos() as f64 / (global_counter as f64 / nprocs as f64)) as u64).to_formatted_string(&Locale::en));
}