| commit | 73e12cb4927184c232234c3b7c0946e6f89008e6 | [log] [tgz] |
|---|---|---|
| author | android-build-team Robot <[email protected]> | Sat Apr 03 03:04:20 2021 +0000 |
| committer | android-build-team Robot <[email protected]> | Sat Apr 03 03:04:20 2021 +0000 |
| tree | b339dd815f3de4e72eb35da7053dbc65098f5c68 | |
| parent | ad4268aa9ef7aa1a2c92a40a96960615da3996d1 [diff] | |
| parent | b3a945f280d46026a8d96575e5d51638871cad07 [diff] |
Snap for 7256110 from b3a945f280d46026a8d96575e5d51638871cad07 to sc-release Change-Id: I6c21738d14ff9f907db5a2925bfb2c5368e0f8b8
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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