| commit | 794825ac02ec14a7d1d0aba3df0573b64016bfb7 | [log] [tgz] |
|---|---|---|
| author | Android Build Coastguard Worker <[email protected]> | Thu Feb 02 05:13:22 2023 +0000 |
| committer | Android Build Coastguard Worker <[email protected]> | Thu Feb 02 05:13:22 2023 +0000 |
| tree | 56bc37db1ea300bbe1dd13de239d70038b816283 | |
| parent | ed8a5b45e314f3574b8e82b550c9f1176bbb1439 [diff] | |
| parent | 995307ffc27e9f46aa59a0fd0813e384da7d26d4 [diff] |
Snap for 9553927 from 995307ffc27e9f46aa59a0fd0813e384da7d26d4 to udc-d1-release Change-Id: Ida2d152afac255f9c0b7089dbe1d97476221ddb6
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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