| commit | 3e6cc320f8fd6d575119a56403fc6598ad8e8abb | [log] [tgz] |
|---|---|---|
| author | Android Build Coastguard Worker <[email protected]> | Sat Oct 21 03:13:42 2023 +0000 |
| committer | Android Build Coastguard Worker <[email protected]> | Sat Oct 21 03:13:42 2023 +0000 |
| tree | 7da7ef40f6c8637accffeb7b81e80b2d09d382af | |
| parent | 1be9e25901f7f6e523d70aa30ad0f7737cd80656 [diff] | |
| parent | a9529cb5b49b04c896de34af15fa4b4640d79150 [diff] |
Snap for 10985023 from a9529cb5b49b04c896de34af15fa4b4640d79150 to 24Q1-release Change-Id: Ic6db612542efd414cf8ba976badec9381ee84f1c
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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