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Fix comments and tweak task exit

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Dániel Buga 2024-12-15 17:44:42 +01:00
parent 5c4983236c
commit e861344b17
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2 changed files with 18 additions and 8 deletions
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21
embassy-executor/src/raw/mod.rs
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@ -94,13 +94,14 @@ impl TaskRef {
&self.header().timer_queue_item
}
/// Mark the task as timer-queued. Return whether it was newly queued (i.e. not queued before)
/// Mark the task as timer-queued. Return whether it should be actually enqueued
/// using `_embassy_time_schedule_wake`.
///
/// Entering this state prevents the task from being respawned while in a timer queue.
///
/// Safety:
///
/// This functions should only be called by the timer queue implementation, before
/// This functions should only be called by the timer queue driver, before
/// enqueueing the timer item.
pub unsafe fn timer_enqueue(&self) -> timer_queue::TimerEnqueueOperation {
self.header().state.timer_enqueue()
@ -193,16 +194,24 @@ impl<F: Future + 'static> TaskStorage<F> {
Poll::Ready(_) => {
this.future.drop_in_place();
// Mark this task to be timer queued, to prevent re-queueing it.
this.raw.state.timer_enqueue();
// Mark this task to be timer queued.
// We're splitting the enqueue in two parts, so that we can change task state
// to something that prevent re-queueing.
let op = this.raw.state.timer_enqueue();
// Now mark the task as not spawned, so that
// - it can be spawned again once it has been removed from the timer queue
// - it can not be timer-queued again
// We must do this before scheduling the wake, to prevent the task from being
// dequeued by the time driver while it's still SPAWNED.
this.raw.state.despawn();
// Schedule the task by hand in the past, so it runs immediately.
unsafe { _embassy_time_schedule_wake(0, &waker) }
// Now let's finish enqueueing. While we shouldn't get an `Ignore` here, it's
// better to be safe.
if op == timer_queue::TimerEnqueueOperation::Enqueue {
// Schedule the task in the past, so it gets dequeued ASAP.
unsafe { _embassy_time_schedule_wake(0, &waker) }
}
}
Poll::Pending => {}
}

5
embassy-executor/src/raw/timer_queue.rs
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@ -30,9 +30,10 @@ impl TimerQueueItem {
/// The operation to perform after `timer_enqueue` is called.
#[derive(Debug, Copy, Clone, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[must_use]
pub enum TimerEnqueueOperation {
/// Enqueue the task.
/// Enqueue the task (or update its expiration time).
Enqueue,
/// Update the task's expiration time.
/// The task must not be enqueued in the timer queue.
Ignore,
}