| commit | cafcc216f61175a9191147d9c0369dc220524c6e | [log] [tgz] |
|---|---|---|
| author | Android Build Coastguard Worker <[email protected]> | Sun Sep 15 07:08:33 2024 +0000 |
| committer | Android Build Coastguard Worker <[email protected]> | Sun Sep 15 07:08:33 2024 +0000 |
| tree | 592703c6d9f929b9ca10de66603dcb156beb8f20 | |
| parent | 003dccf724165af10c81aa177d10ef572dfe1b01 [diff] | |
| parent | 7972c8dc49c2de95f45f2b353c84a08f827735c5 [diff] |
Snap for 12356763 from 7972c8dc49c2de95f45f2b353c84a08f827735c5 to busytown-mac-infra-release Change-Id: Ib6758b398669f7d13b024735fedd6c07278c7e0c
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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