[−][src]Crate async_task_ffi
Task abstraction for building executors.
This is a fork of async-task with additional features useful for ffi based 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()
,
spawn_unchecked()
or their _with
variants 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_ffi::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.
Structs
Runnable | A handle to a runnable task. |
Task | A spawned task. |
Functions
spawn | Creates a new task. |
spawn_local | Creates a new thread-local task. |
spawn_local_with | Creates a new thread-local task with associated data. |
spawn_unchecked⚠ | |
spawn_unchecked_with⚠ | Creates a new task with associated data and without |
spawn_with | Creates a new task with associated data. |