78 lines
2 KiB
Rust
78 lines
2 KiB
Rust
use core::cell::Cell;
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use core::cmp::min;
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use atomic_polyfill::Ordering;
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use embassy_time::Instant;
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use super::{TaskRef, STATE_TIMER_QUEUED};
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pub(crate) struct TimerQueueItem {
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next: Cell<Option<TaskRef>>,
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}
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impl TimerQueueItem {
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pub const fn new() -> Self {
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Self { next: Cell::new(None) }
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}
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}
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pub(crate) struct TimerQueue {
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head: Cell<Option<TaskRef>>,
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}
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impl TimerQueue {
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pub const fn new() -> Self {
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Self { head: Cell::new(None) }
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}
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pub(crate) unsafe fn update(&self, p: TaskRef) {
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let task = p.header();
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if task.expires_at.get() != Instant::MAX {
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let old_state = task.state.fetch_or(STATE_TIMER_QUEUED, Ordering::AcqRel);
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let is_new = old_state & STATE_TIMER_QUEUED == 0;
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if is_new {
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task.timer_queue_item.next.set(self.head.get());
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self.head.set(Some(p));
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}
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}
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}
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pub(crate) unsafe fn next_expiration(&self) -> Instant {
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let mut res = Instant::MAX;
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self.retain(|p| {
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let task = p.header();
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let expires = task.expires_at.get();
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res = min(res, expires);
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expires != Instant::MAX
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});
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res
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}
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pub(crate) unsafe fn dequeue_expired(&self, now: Instant, on_task: impl Fn(TaskRef)) {
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self.retain(|p| {
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let task = p.header();
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if task.expires_at.get() <= now {
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on_task(p);
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false
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} else {
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true
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}
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});
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}
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pub(crate) unsafe fn retain(&self, mut f: impl FnMut(TaskRef) -> bool) {
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let mut prev = &self.head;
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while let Some(p) = prev.get() {
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let task = p.header();
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if f(p) {
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// Skip to next
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prev = &task.timer_queue_item.next;
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} else {
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// Remove it
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prev.set(task.timer_queue_item.next.get());
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task.state.fetch_and(!STATE_TIMER_QUEUED, Ordering::AcqRel);
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}
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}
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}
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}
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