| commit | 9ecfb1a7ae3883e926be2068959245dcb3c690ca | [log] [tgz] |
|---|---|---|
| author | Joel Galenson <jgalenson@google.com> | Mon Aug 30 21:50:07 2021 +0000 |
| committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Mon Aug 30 21:50:07 2021 +0000 |
| tree | ddb444569a5fe41c99dfc132b738468aac5d2827 | |
| parent | 19f668823af881ac00cd9b505b4485ca33a1d5c1 [diff] | |
| parent | acc37b4e426c08995420fe0d5a2e5a6692766971 [diff] |
Update TEST_MAPPING am: 912821e0d9 am: 557e9d0253 am: 23807200fa am: acc37b4e42 Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/async-task/+/1813676 Change-Id: I15b04a375fff55aafb2becdb36a5021572589f0e
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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