commit | 6859d46ffc2252e181aef46ca4367c1e32e53769 | [log] [tgz] |
---|---|---|
author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Wed Apr 06 20:36:10 2022 +0000 |
committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Wed Apr 06 20:36:10 2022 +0000 |
tree | a8c0195dcd49ed82252eacb02eecc46b2bc3cc63 | |
parent | a0784645fdcde1ef1d470726b69c741eadf630f3 [diff] | |
parent | e12d2cfcff2456cbe3c7ff1974ff288b7c1c381e [diff] |
Snap for 8414339 from e12d2cfcff2456cbe3c7ff1974ff288b7c1c381e to tm-qpr1-release Change-Id: I98aaa8d801345cf88b7a7ea8a0c4c318fa31fb83
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.
Licensed under either of
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.