commit | b84c56f8db8523f9453a6293c881e06aca89a318 | [log] [tgz] |
---|---|---|
author | Joel Galenson <jgalenson@google.com> | Tue Nov 30 20:46:32 2021 +0000 |
committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Tue Nov 30 20:46:32 2021 +0000 |
tree | 68ae9903db4f572e5ea6388cdecf53b12e4e5045 | |
parent | acc37b4e426c08995420fe0d5a2e5a6692766971 [diff] | |
parent | 8c3a49783175022e5a1a3d6a95e6deab36a2781b [diff] |
Fix incorrect cargo2android.py invocation. am: efb74b1650 am: 8c3a497831 Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/async-task/+/1906970 Change-Id: I37a454fdd6934e2414a3ce0315265bbc55e32b8f
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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