Move Task into raw

embassy-macros/src/lib.rs

@@ -100,11 +100,12 @@ pub fn task(args: TokenStream, item: TokenStream) -> TokenStream {
 
     let result = quote! {
         #visibility fn #name(#args) -> ::embassy::executor::SpawnToken<#impl_ty> {
+            use ::embassy::executor::raw::Task;
             #task_fn
             type F = #impl_ty;
-            const NEW_TASK: ::embassy::executor::Task<F> = ::embassy::executor::Task::new();
-            static POOL: [::embassy::executor::Task<F>; #pool_size] = [NEW_TASK; #pool_size];
-            unsafe { ::embassy::executor::Task::spawn(&POOL, move || task(#arg_names)) }
+            const NEW_TASK: Task<F> = Task::new();
+            static POOL: [Task<F>; #pool_size] = [NEW_TASK; #pool_size];
+            unsafe { Task::spawn(&POOL, move || task(#arg_names)) }
         }
     };
     result.into()

embassy/src/executor/mod.rs

@@ -20,71 +20,9 @@ use crate::fmt::panic;
 use crate::interrupt::{Interrupt, InterruptExt};
 use crate::time::Alarm;
 
-// repr(C) is needed to guarantee that the raw::Task is located at offset 0
-// This makes it safe to cast between raw::Task and Task pointers.
-#[repr(C)]
-pub struct Task<F: Future + 'static> {
-    raw: raw::Task,
-    future: UninitCell<F>, // Valid if STATE_SPAWNED
-}
-
-impl<F: Future + 'static> Task<F> {
-    pub const fn new() -> Self {
-        Self {
-            raw: raw::Task::new(),
-            future: UninitCell::uninit(),
-        }
-    }
-
-    pub unsafe fn spawn(pool: &'static [Self], future: impl FnOnce() -> F) -> SpawnToken<F> {
-        for task in pool {
-            let state = raw::STATE_SPAWNED | raw::STATE_RUN_QUEUED;
-            if task
-                .raw
-                .state
-                .compare_exchange(0, state, Ordering::AcqRel, Ordering::Acquire)
-                .is_ok()
-            {
-                // Initialize the task
-                task.raw.poll_fn.write(Self::poll);
-                task.future.write(future());
-
-                return SpawnToken {
-                    raw_task: Some(NonNull::new_unchecked(&task.raw as *const raw::Task as _)),
-                    phantom: PhantomData,
-                };
-            }
-        }
-
-        SpawnToken {
-            raw_task: None,
-            phantom: PhantomData,
-        }
-    }
-
-    unsafe fn poll(p: NonNull<raw::Task>) {
-        let this = &*(p.as_ptr() as *const Task<F>);
-
-        let future = Pin::new_unchecked(this.future.as_mut());
-        let waker = waker::from_task(p);
-        let mut cx = Context::from_waker(&waker);
-        match future.poll(&mut cx) {
-            Poll::Ready(_) => {
-                this.future.drop_in_place();
-                this.raw
-                    .state
-                    .fetch_and(!raw::STATE_SPAWNED, Ordering::AcqRel);
-            }
-            Poll::Pending => {}
-        }
-    }
-}
-
-unsafe impl<F: Future + 'static> Sync for Task<F> {}
-
 #[must_use = "Calling a task function does nothing on its own. You must pass the returned SpawnToken to Executor::spawn()"]
 pub struct SpawnToken<F> {
-    raw_task: Option<NonNull<raw::Task>>,
+    raw_task: Option<NonNull<raw::TaskHeader>>,
     phantom: PhantomData<*mut F>,
 }
 

embassy/src/executor/raw.rs

@@ -1,15 +1,18 @@
 use atomic_polyfill::{AtomicU32, Ordering};
 use core::cell::Cell;
 use core::cmp::min;
+use core::future::Future;
 use core::marker::PhantomData;
+use core::pin::Pin;
 use core::ptr;
 use core::ptr::NonNull;
-use core::task::Waker;
+use core::task::{Context, Poll, Waker};
 
 use super::run_queue::{RunQueue, RunQueueItem};
 use super::timer_queue::{TimerQueue, TimerQueueItem};
 use super::util::UninitCell;
 use super::waker;
+use super::SpawnToken;
 use crate::time::{Alarm, Instant};
 
 /// Task is spawned (has a future)
@@ -19,16 +22,16 @@ pub(crate) const STATE_RUN_QUEUED: u32 = 1 << 1;
 /// Task is in the executor timer queue
 pub(crate) const STATE_TIMER_QUEUED: u32 = 1 << 2;
 
-pub struct Task {
+pub struct TaskHeader {
     pub(crate) state: AtomicU32,
     pub(crate) run_queue_item: RunQueueItem,
     pub(crate) expires_at: Cell<Instant>,
     pub(crate) timer_queue_item: TimerQueueItem,
     pub(crate) executor: Cell<*const Executor>, // Valid if state != 0
-    pub(crate) poll_fn: UninitCell<unsafe fn(NonNull<Task>)>, // Valid if STATE_SPAWNED
+    pub(crate) poll_fn: UninitCell<unsafe fn(NonNull<TaskHeader>)>, // Valid if STATE_SPAWNED
 }
 
-impl Task {
+impl TaskHeader {
     pub(crate) const fn new() -> Self {
         Self {
             state: AtomicU32::new(0),
@@ -64,10 +67,70 @@ impl Task {
 
         // We have just marked the task as scheduled, so enqueue it.
         let executor = &*self.executor.get();
-        executor.enqueue(self as *const Task as *mut Task);
+        executor.enqueue(self as *const TaskHeader as *mut TaskHeader);
     }
 }
 
+// repr(C) is needed to guarantee that the Task is located at offset 0
+// This makes it safe to cast between Task and Task pointers.
+#[repr(C)]
+pub struct Task<F: Future + 'static> {
+    raw: TaskHeader,
+    future: UninitCell<F>, // Valid if STATE_SPAWNED
+}
+
+impl<F: Future + 'static> Task<F> {
+    pub const fn new() -> Self {
+        Self {
+            raw: TaskHeader::new(),
+            future: UninitCell::uninit(),
+        }
+    }
+
+    pub unsafe fn spawn(pool: &'static [Self], future: impl FnOnce() -> F) -> SpawnToken<F> {
+        for task in pool {
+            let state = STATE_SPAWNED | STATE_RUN_QUEUED;
+            if task
+                .raw
+                .state
+                .compare_exchange(0, state, Ordering::AcqRel, Ordering::Acquire)
+                .is_ok()
+            {
+                // Initialize the task
+                task.raw.poll_fn.write(Self::poll);
+                task.future.write(future());
+
+                return SpawnToken {
+                    raw_task: Some(NonNull::new_unchecked(&task.raw as *const TaskHeader as _)),
+                    phantom: PhantomData,
+                };
+            }
+        }
+
+        SpawnToken {
+            raw_task: None,
+            phantom: PhantomData,
+        }
+    }
+
+    unsafe fn poll(p: NonNull<TaskHeader>) {
+        let this = &*(p.as_ptr() as *const Task<F>);
+
+        let future = Pin::new_unchecked(this.future.as_mut());
+        let waker = waker::from_task(p);
+        let mut cx = Context::from_waker(&waker);
+        match future.poll(&mut cx) {
+            Poll::Ready(_) => {
+                this.future.drop_in_place();
+                this.raw.state.fetch_and(!STATE_SPAWNED, Ordering::AcqRel);
+            }
+            Poll::Pending => {}
+        }
+    }
+}
+
+unsafe impl<F: Future + 'static> Sync for Task<F> {}
+
 pub struct Executor {
     run_queue: RunQueue,
     timer_queue: TimerQueue,
@@ -95,13 +158,13 @@ impl Executor {
         self.signal_ctx = signal_ctx;
     }
 
-    unsafe fn enqueue(&self, item: *mut Task) {
+    unsafe fn enqueue(&self, item: *mut TaskHeader) {
         if self.run_queue.enqueue(item) {
             (self.signal_fn)(self.signal_ctx)
         }
     }
 
-    pub unsafe fn spawn(&'static self, task: NonNull<Task>) {
+    pub unsafe fn spawn(&'static self, task: NonNull<TaskHeader>) {
         let task = task.as_ref();
         task.executor.set(self);
         self.enqueue(task as *const _ as _);
@@ -154,7 +217,7 @@ impl Executor {
 
 pub use super::waker::task_from_waker;
 
-pub unsafe fn wake_task(task: NonNull<Task>) {
+pub unsafe fn wake_task(task: NonNull<TaskHeader>) {
     task.as_ref().enqueue();
 }
 

embassy/src/executor/run_queue.rs

@@ -2,10 +2,10 @@ use atomic_polyfill::{AtomicPtr, Ordering};
 use core::ptr;
 use core::ptr::NonNull;
 
-use super::raw::Task;
+use super::raw::TaskHeader;
 
 pub(crate) struct RunQueueItem {
-    next: AtomicPtr<Task>,
+    next: AtomicPtr<TaskHeader>,
 }
 
 impl RunQueueItem {
@@ -28,7 +28,7 @@ impl RunQueueItem {
 /// current batch is completely processed, so even if a task enqueues itself instantly (for example
 /// by waking its own waker) can't prevent other tasks from running.
 pub(crate) struct RunQueue {
-    head: AtomicPtr<Task>,
+    head: AtomicPtr<TaskHeader>,
 }
 
 impl RunQueue {
@@ -39,7 +39,7 @@ impl RunQueue {
     }
 
     /// Enqueues an item. Returns true if the queue was empty.
-    pub(crate) unsafe fn enqueue(&self, item: *mut Task) -> bool {
+    pub(crate) unsafe fn enqueue(&self, item: *mut TaskHeader) -> bool {
         let mut prev = self.head.load(Ordering::Acquire);
         loop {
             (*item).run_queue_item.next.store(prev, Ordering::Relaxed);
@@ -55,7 +55,7 @@ impl RunQueue {
         prev.is_null()
     }
 
-    pub(crate) unsafe fn dequeue_all(&self, on_task: impl Fn(NonNull<Task>)) {
+    pub(crate) unsafe fn dequeue_all(&self, on_task: impl Fn(NonNull<TaskHeader>)) {
         let mut task = self.head.swap(ptr::null_mut(), Ordering::AcqRel);
 
         while !task.is_null() {

embassy/src/executor/timer_queue.rs

@@ -4,11 +4,11 @@ use core::cmp::min;
 use core::ptr;
 use core::ptr::NonNull;
 
-use super::raw::{Task, STATE_TIMER_QUEUED};
+use super::raw::{TaskHeader, STATE_TIMER_QUEUED};
 use crate::time::Instant;
 
 pub(crate) struct TimerQueueItem {
-    next: Cell<*mut Task>,
+    next: Cell<*mut TaskHeader>,
 }
 
 impl TimerQueueItem {
@@ -20,7 +20,7 @@ impl TimerQueueItem {
 }
 
 pub(crate) struct TimerQueue {
-    head: Cell<*mut Task>,
+    head: Cell<*mut TaskHeader>,
 }
 
 impl TimerQueue {
@@ -30,7 +30,7 @@ impl TimerQueue {
         }
     }
 
-    pub(crate) unsafe fn update(&self, p: NonNull<Task>) {
+    pub(crate) unsafe fn update(&self, p: NonNull<TaskHeader>) {
         let task = p.as_ref();
         if task.expires_at.get() != Instant::MAX {
             let old_state = task.state.fetch_or(STATE_TIMER_QUEUED, Ordering::AcqRel);
@@ -54,7 +54,11 @@ impl TimerQueue {
         res
     }
 
-    pub(crate) unsafe fn dequeue_expired(&self, now: Instant, on_task: impl Fn(NonNull<Task>)) {
+    pub(crate) unsafe fn dequeue_expired(
+        &self,
+        now: Instant,
+        on_task: impl Fn(NonNull<TaskHeader>),
+    ) {
         self.retain(|p| {
             let task = p.as_ref();
             if task.expires_at.get() <= now {
@@ -66,7 +70,7 @@ impl TimerQueue {
         });
     }
 
-    pub(crate) unsafe fn retain(&self, mut f: impl FnMut(NonNull<Task>) -> bool) {
+    pub(crate) unsafe fn retain(&self, mut f: impl FnMut(NonNull<TaskHeader>) -> bool) {
         let mut prev = &self.head;
         while !prev.get().is_null() {
             let p = NonNull::new_unchecked(prev.get());

embassy/src/executor/waker.rs

@@ -2,7 +2,7 @@ use core::mem;
 use core::ptr::NonNull;
 use core::task::{RawWaker, RawWakerVTable, Waker};
 
-use super::raw::Task;
+use super::raw::TaskHeader;
 
 const VTABLE: RawWakerVTable = RawWakerVTable::new(clone, wake, wake, drop);
 
@@ -11,21 +11,21 @@ unsafe fn clone(p: *const ()) -> RawWaker {
 }
 
 unsafe fn wake(p: *const ()) {
-    (*(p as *mut Task)).enqueue()
+    (*(p as *mut TaskHeader)).enqueue()
 }
 
 unsafe fn drop(_: *const ()) {
     // nop
 }
 
-pub(crate) unsafe fn from_task(p: NonNull<Task>) -> Waker {
+pub(crate) unsafe fn from_task(p: NonNull<TaskHeader>) -> Waker {
     Waker::from_raw(RawWaker::new(p.as_ptr() as _, &VTABLE))
 }
 
-pub unsafe fn task_from_waker(waker: &Waker) -> NonNull<Task> {
+pub unsafe fn task_from_waker(waker: &Waker) -> NonNull<TaskHeader> {
     let hack: &WakerHack = mem::transmute(waker);
     assert_eq!(hack.vtable, &VTABLE);
-    NonNull::new_unchecked(hack.data as *mut Task)
+    NonNull::new_unchecked(hack.data as *mut TaskHeader)
 }
 
 struct WakerHack {

embassy/src/util/waker.rs

@@ -3,12 +3,12 @@ use core::task::Waker;
 
 use atomic_polyfill::{AtomicPtr, Ordering};
 
-use crate::executor::raw::{task_from_waker, wake_task, Task};
+use crate::executor::raw::{task_from_waker, wake_task, TaskHeader};
 
 /// Utility struct to register and wake a waker.
 #[derive(Debug)]
 pub struct WakerRegistration {
-    waker: Option<NonNull<Task>>,
+    waker: Option<NonNull<TaskHeader>>,
 }
 
 impl WakerRegistration {
@@ -49,7 +49,7 @@ impl WakerRegistration {
 }
 
 pub struct AtomicWakerRegistration {
-    waker: AtomicPtr<Task>,
+    waker: AtomicPtr<TaskHeader>,
 }
 
 impl AtomicWakerRegistration {