Move integrated timer queue into time-queue-driver

embassy-executor/CHANGELOG.md

@@ -10,7 +10,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - embassy-executor no longer provides an `embassy-time-queue-driver` implementation
 - Added `TaskRef::executor` to obtain a reference to a task's executor
 - integrated-timers are no longer processed when polling the executor.
-- `raw::timer_queue::TimerQueue` is now public.
 
 ## 0.6.3 - 2024-11-12
 

embassy-executor/src/raw/timer_queue.rs

@@ -1,99 +1,25 @@
 //! Timer queue operations.
-use core::cmp::min;
 
-use super::util::SyncUnsafeCell;
+use core::cell::Cell;
+
 use super::TaskRef;
 
 /// An item in the timer queue.
 pub struct TimerQueueItem {
-    next: SyncUnsafeCell<Option<TaskRef>>,
-    expires_at: SyncUnsafeCell<u64>,
+    /// The next item in the queue.
+    pub next: Cell<Option<TaskRef>>,
+
+    /// The time at which this item expires.
+    pub expires_at: Cell<u64>,
 }
 
+unsafe impl Sync for TimerQueueItem {}
+
 impl TimerQueueItem {
     pub(crate) const fn new() -> Self {
         Self {
-            next: SyncUnsafeCell::new(None),
-            expires_at: SyncUnsafeCell::new(0),
-        }
-    }
-}
-
-/// A timer queue, with items integrated into tasks.
-pub struct TimerQueue {
-    head: SyncUnsafeCell<Option<TaskRef>>,
-}
-
-impl TimerQueue {
-    /// Creates a new timer queue.
-    pub const fn new() -> Self {
-        Self {
-            head: SyncUnsafeCell::new(None),
-        }
-    }
-
-    /// Schedules a task to run at a specific time.
-    ///
-    /// If this function returns `true`, the called should find the next expiration time and set
-    /// a new alarm for that time.
-    pub fn schedule_wake(&mut self, at: u64, p: TaskRef) -> bool {
-        unsafe {
-            let item = p.timer_queue_item();
-            if item.next.get().is_none() {
-                // If not in the queue, add it and update.
-                let prev = self.head.replace(Some(p));
-                item.next.set(prev);
-            } else if at <= item.expires_at.get() {
-                // If expiration is sooner than previously set, update.
-            } else {
-                // Task does not need to be updated.
-                return false;
-            }
-
-            item.expires_at.set(at);
-            true
-        }
-    }
-
-    /// Dequeues expired timers and returns the next alarm time.
-    ///
-    /// The provided callback will be called for each expired task. Tasks that never expire
-    /// will be removed, but the callback will not be called.
-    pub fn next_expiration(&mut self, now: u64) -> u64 {
-        let mut next_expiration = u64::MAX;
-
-        self.retain(|p| {
-            let item = p.timer_queue_item();
-            let expires = unsafe { item.expires_at.get() };
-
-            if expires <= now {
-                // Timer expired, process task.
-                super::wake_task(p);
-                false
-            } else {
-                // Timer didn't yet expire, or never expires.
-                next_expiration = min(next_expiration, expires);
-                expires != u64::MAX
-            }
-        });
-
-        next_expiration
-    }
-
-    fn retain(&self, mut f: impl FnMut(TaskRef) -> bool) {
-        unsafe {
-            let mut prev = &self.head;
-            while let Some(p) = prev.get() {
-                let item = p.timer_queue_item();
-                if f(p) {
-                    // Skip to next
-                    prev = &item.next;
-                } else {
-                    // Remove it
-                    prev.set(item.next.get());
-                    item.next.set(None);
-                }
-            }
+            next: Cell::new(None),
+            expires_at: Cell::new(0),
         }
     }
 }

embassy-executor/src/raw/util.rs

@@ -54,9 +54,4 @@ impl<T> SyncUnsafeCell<T> {
     {
         *self.value.get()
     }
-
-    #[cfg(feature = "integrated-timers")]
-    pub unsafe fn replace(&self, value: T) -> T {
-        core::mem::replace(&mut *self.value.get(), value)
-    }
 }

embassy-time-queue-driver/src/lib.rs

@@ -22,9 +22,9 @@
 //! );
 //! ```
 //!
-//! You can also use the `queue_generic` or the `embassy_executor::raw::timer_queue` modules to
-//! implement your own timer queue. These modules contain queue implementations which you can wrap
-//! and tailor to your needs.
+//! You can also use the `queue_generic` or the `queue_integrated` modules to implement your own
+//! timer queue. These modules contain queue implementations which you can wrap and tailor to
+//! your needs.
 //!
 //! If you are providing an embassy-executor implementation besides a timer queue, you can choose to
 //! expose the `integrated-timers` feature in your implementation. This feature stores timer items
@@ -49,7 +49,10 @@
 //! embassy_time_queue_driver::timer_queue_impl!(static QUEUE: MyTimerQueue = MyTimerQueue{});
 //! ```
 
+#[cfg(not(feature = "integrated-timers"))]
 pub mod queue_generic;
+#[cfg(feature = "integrated-timers")]
+pub mod queue_integrated;
 
 use core::cell::RefCell;
 use core::task::Waker;
@@ -89,7 +92,7 @@ macro_rules! timer_queue_impl {
 }
 
 #[cfg(feature = "integrated-timers")]
-type InnerQueue = embassy_executor::raw::timer_queue::TimerQueue;
+type InnerQueue = queue_integrated::TimerQueue;
 
 #[cfg(not(feature = "integrated-timers"))]
 type InnerQueue = queue_generic::Queue;

embassy-time-queue-driver/src/queue_integrated.rs

@@ -0,0 +1,78 @@
+//! Timer queue operations.
+use core::cell::Cell;
+use core::cmp::min;
+
+use embassy_executor::raw::TaskRef;
+
+/// A timer queue, with items integrated into tasks.
+pub struct TimerQueue {
+    head: Cell<Option<TaskRef>>,
+}
+
+impl TimerQueue {
+    /// Creates a new timer queue.
+    pub const fn new() -> Self {
+        Self { head: Cell::new(None) }
+    }
+
+    /// Schedules a task to run at a specific time.
+    ///
+    /// If this function returns `true`, the called should find the next expiration time and set
+    /// a new alarm for that time.
+    pub fn schedule_wake(&mut self, at: u64, p: TaskRef) -> bool {
+        let item = p.timer_queue_item();
+        if item.next.get().is_none() {
+            // If not in the queue, add it and update.
+            let prev = self.head.replace(Some(p));
+            item.next.set(prev);
+        } else if at <= item.expires_at.get() {
+            // If expiration is sooner than previously set, update.
+        } else {
+            // Task does not need to be updated.
+            return false;
+        }
+
+        item.expires_at.set(at);
+        true
+    }
+
+    /// Dequeues expired timers and returns the next alarm time.
+    ///
+    /// The provided callback will be called for each expired task. Tasks that never expire
+    /// will be removed, but the callback will not be called.
+    pub fn next_expiration(&mut self, now: u64) -> u64 {
+        let mut next_expiration = u64::MAX;
+
+        self.retain(|p| {
+            let item = p.timer_queue_item();
+            let expires = item.expires_at.get();
+
+            if expires <= now {
+                // Timer expired, process task.
+                embassy_executor::raw::wake_task(p);
+                false
+            } else {
+                // Timer didn't yet expire, or never expires.
+                next_expiration = min(next_expiration, expires);
+                expires != u64::MAX
+            }
+        });
+
+        next_expiration
+    }
+
+    fn retain(&self, mut f: impl FnMut(TaskRef) -> bool) {
+        let mut prev = &self.head;
+        while let Some(p) = prev.get() {
+            let item = p.timer_queue_item();
+            if f(p) {
+                // Skip to next
+                prev = &item.next;
+            } else {
+                // Remove it
+                prev.set(item.next.get());
+                item.next.set(None);
+            }
+        }
+    }
+}