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rust asynchronous task manager built on top of tokio framework supporting task cancellation feature


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coachman is a rust asynchronous task manager built on top of tokio framework.


  • Task count control: coachman allows you to control task count preventing your application from uncontrolled task count explosion.
  • Task cancellation: The main feature of coachman is task cancellation. It provides a simple api for making your task cancelable.

Basic example

The main feature of coachman is making asynchronous tasks cancelable.

Look at the following example:

use coachman as cm;
use coachman::{try_await, Canceled, Completed, TaskError};

async fn inner_func(i: usize, duration: u64) {
   match try_await!(tokio::time::sleep(std::time::Duration::from_secs(duration))) {
       Canceled => println!("task#{} inner canceled", i),
       Completed(_) => println!("task#{} inner completed", i),

async fn outer_func(i: usize, duration: u64) {
   match try_await!(inner_func(i, duration)) {
       Canceled => println!("task#{} outer canceled", i),
       Completed(_) => println!("task#{} outer completed", i),

#[tokio::main(flavor = "current_thread")]
async fn main() {
   let mut task_handles = Vec::new();
   for i in 0..5 {
       let duration = i as u64;
       task_handles.push(cm::spawn(outer_func(i, duration)));

   let deadline = tokio::time::Instant::now() + std::time::Duration::from_secs(2);
   for (i, mut handle) in task_handles.into_iter().enumerate() {
       if tokio::time::timeout_at(deadline, &mut handle).await.is_ok() {
           println!("task-{} completed", i);
       } else {
           match handle.await {
               Result::Err(TaskError::Canceled) => println!("task-{} canceled", i),
               Result::Err(TaskError::Aborted) => println!("task-{} aborted", i),
               Result::Err(TaskError::Panicked(_)) => println!("task-{} panicked", i),
               Result::Ok(_) => unreachable!(),