| commit | 290ec8875edd9edaa689daa1a0cc1f246deea01e | [log] [tgz] |
|---|---|---|
| author | Treehugger Robot <[email protected]> | Tue Mar 08 21:25:02 2022 +0000 |
| committer | Automerger Merge Worker <[email protected]> | Tue Mar 08 21:25:02 2022 +0000 |
| tree | a8c0195dcd49ed82252eacb02eecc46b2bc3cc63 | |
| parent | 861110de978d507bcc2b12b375d44923f6809b41 [diff] | |
| parent | 973da9d0db4deeb9cfdfe64b2c9f1dc30bfe7b44 [diff] |
Merge "Update async-task to 4.1.0" am: 1b4f067822 am: 973da9d0db Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/async-task/+/2004692 Change-Id: I3aec3ed8fb395685359448bd2d1c390809c060e9
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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