| commit | d9af5d74c3f4fc5a9fb5dcaf5a2b0366d0630b13 | [log] [tgz] |
|---|---|---|
| author | Android Build Coastguard Worker <[email protected]> | Thu Aug 15 23:16:38 2024 +0000 |
| committer | Android Build Coastguard Worker <[email protected]> | Thu Aug 15 23:16:38 2024 +0000 |
| tree | 592703c6d9f929b9ca10de66603dcb156beb8f20 | |
| parent | a345cde5e1a07469b557aa6ba5412deff8e51485 [diff] | |
| parent | 482244ef197109493823c6d329634ae440841e56 [diff] |
Snap for 12235283 from 482244ef197109493823c6d329634ae440841e56 to 25D4-release Change-Id: I1139c3f9efe140341eaa815a11a75714756d721a
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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