| commit | a0784645fdcde1ef1d470726b69c741eadf630f3 | [log] [tgz] |
|---|---|---|
| author | Joel Galenson <[email protected]> | Wed Dec 29 16:09:59 2021 +0000 |
| committer | Automerger Merge Worker <[email protected]> | Wed Dec 29 16:09:59 2021 +0000 |
| tree | ecd6a30f5a1c8ce7f993f099c3cbaced8626e0e2 | |
| parent | 63de6effa3514aef95c03953dbd4bee23109d5b3 [diff] | |
| parent | 861110de978d507bcc2b12b375d44923f6809b41 [diff] |
Add missed TEST_MAPPINGs am: 0c32039e62 am: 21c5c90c9d am: 7165c3737a am: 861110de97 Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/async-task/+/1924497 Change-Id: I5026152798e1f8db41950a64849b0dc059496483
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.
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