import context
import time
import x.async as xasync

fn main() {
    mut pool := xasync.new_pool(workers: 1, queue_size: 1)!
    started := chan int{cap: 2}
    release := chan bool{cap: 2}
    job := fn [started, release] (mut ctx context.Context) ! {
        _ = ctx
        started <- 1
        _ := <-release
    }

    pool.try_submit(job)!
    if !wait_started(started) {
        eprintln('pool job did not start')
        exit(1)
    }

    pool.try_submit(job)!
    pool.try_submit(job) or { println('backpressure: ${err.msg()}') }

    release <- true
    if !wait_started(started) {
        eprintln('pool job did not start')
        exit(1)
    }
    release <- true

    pool.close()!
    println('pool drained')
}

fn wait_started(started chan int) bool {
    select {
        _ := <-started {
            return true
        }
        1 * time.second {
            return false
        }
    }
    return false
}