Bug: 180427432

Clone this repo:
  1. 0c32039 Add missed TEST_MAPPINGs by Joel Galenson · 5 weeks ago master
  2. 8c3a497 Fix incorrect cargo2android.py invocation. am: efb74b1650 by Joel Galenson · 7 weeks ago
  3. efb74b1 Fix incorrect cargo2android.py invocation. by Joel Galenson · 7 weeks ago
  4. acc37b4 Update TEST_MAPPING am: 912821e0d9 am: 557e9d0253 am: 23807200fa by Joel Galenson · 5 months ago
  5. 2380720 Update TEST_MAPPING am: 912821e0d9 am: 557e9d0253 by Joel Galenson · 5 months ago

async-task

Build License Cargo Documentation

Task abstraction for building executors.

To spawn a future onto an executor, we first need to allocate it on the heap and keep some state attached to it. The state indicates whether the future is ready for polling, waiting to be woken up, or completed. Such a stateful future is called a task.

All executors have a queue that holds scheduled tasks:

let (sender, receiver) = flume::unbounded();

A task is created using either spawn(), spawn_local(), or spawn_unchecked() which return a Runnable and a Task:

// A future that will be spawned.
let future = async { 1 + 2 };

// A function that schedules the task when it gets woken up.
let schedule = move |runnable| sender.send(runnable).unwrap();

// Construct a task.
let (runnable, task) = async_task::spawn(future, schedule);

// Push the task into the queue by invoking its schedule function.
runnable.schedule();

The Runnable is used to poll the task's future, and the Task is used to await its output.

Finally, we need a loop that takes scheduled tasks from the queue and runs them:

for runnable in receiver {
    runnable.run();
}

Method run() polls the task's future once. Then, the Runnable vanishes and only reappears when its Waker wakes the task, thus scheduling it to be run again.

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.