| commit | d9b0f8364edd5389fe691bbd09ba01a9d862678e | [log] [tgz] |
|---|---|---|
| author | Android Build Coastguard Worker <[email protected]> | Fri Mar 10 04:19:27 2023 +0000 |
| committer | Automerger Merge Worker <[email protected]> | Fri Mar 10 04:19:27 2023 +0000 |
| tree | 920f690346620be8f3e538141249f6331fa01d4e | |
| parent | 995307ffc27e9f46aa59a0fd0813e384da7d26d4 [diff] | |
| parent | fd5179e71464a99e34f0dac9eee748493527abac [diff] |
Snap for 9719949 from 4d4b2dbe48f6647fef35390ae8a55c40eb9d2293 to udc-release am: fd5179e714 Original change: https://googleplex-android-review.googlesource.com/c/platform/external/rust/crates/async-task/+/21946151 Change-Id: I5c3e608e27489e3d45e8d27d17e2968f7c2cbfca Signed-off-by: Automerger Merge Worker <[email protected]>
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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