libasync: replace executor Mutexes with RefCells

this will not run on multi-core.
This commit is contained in:
Astro 2020-03-26 20:29:36 +01:00
parent 5b95410244
commit ea765fc529
1 changed files with 20 additions and 16 deletions

View File

@ -1,17 +1,16 @@
use core::{
cell::{Cell, UnsafeCell},
cell::{RefCell, UnsafeCell},
future::Future,
mem::MaybeUninit,
pin::Pin,
sync::atomic::{self, AtomicBool, Ordering},
sync::atomic::{AtomicBool, Ordering},
task::{Context, Poll, RawWaker, RawWakerVTable, Waker},
};
use alloc::{boxed::Box, collections::VecDeque as Deque};
//use futures::future::FutureExt;
use pin_utils::pin_mut;
use libcortex_a9::mutex::Mutex;
// TODO: delete
use libboard_zynq::println;
//use libboard_zynq::println;
// NOTE `*const ()` is &AtomicBool
static VTABLE: RawWakerVTable = {
@ -35,16 +34,16 @@ static VTABLE: RawWakerVTable = {
///
/// This is a singleton
pub struct Executor {
in_block_on: Mutex<bool>,
tasks: Mutex<Deque<Task>>,
in_block_on: RefCell<bool>,
tasks: RefCell<Deque<Task>>,
}
impl Executor {
/// Creates a new instance of the executor
pub fn new() -> Self {
Self {
in_block_on: Mutex::new(false),
tasks: Mutex::new(Deque::new()),
in_block_on: RefCell::new(false),
tasks: RefCell::new(Deque::new()),
}
}
@ -54,7 +53,7 @@ impl Executor {
// application will only call `block_on` once on an infinite task
// (`Future<Output = !>`)
{
let mut in_block_on = self.in_block_on.lock();
let mut in_block_on = self.in_block_on.borrow_mut();
if *in_block_on {
panic!("nested `block_on`");
}
@ -70,14 +69,17 @@ impl Executor {
if ready.load(Ordering::Relaxed) {
ready.store(false, Ordering::Relaxed);
// println!("run block_on");
let mut cx = Context::from_waker(&waker);
if let Poll::Ready(val) = f.as_mut().poll(&mut cx) {
break val;
}
// println!("ran block_on");
}
// println!("tasks: {}", self.tasks.borrow().len());
// advance other tasks
let next_task = self.tasks.lock().pop_front();
let next_task = self.tasks.borrow_mut().pop_front();
if let Some(mut task) = next_task {
// NOTE we don't need a CAS operation here because `wake` invocations that come from
// interrupt handlers (the only source of 'race conditions' (!= data races)) are
@ -94,14 +96,16 @@ impl Executor {
};
let mut cx = Context::from_waker(&waker);
// this points into a `static` memory so it's already pinned
let r = unsafe {
// println!("run task");
let ready = unsafe {
Pin::new_unchecked(&mut *task.f)
.poll(&mut cx)
.is_ready()
};
if !r {
// println!("ran task, ready={:?}", r);
if !ready {
// Task is not finished, requeue
self.tasks.lock().push_back(task);
self.tasks.borrow_mut().push_back(task);
}
}
}
@ -110,7 +114,7 @@ impl Executor {
// // interrupt ran (regardless of whether it generated a wake-up or not)
// asm::wfe();
};
*self.in_block_on.lock() = false;
self.in_block_on.replace(false);
val
}
@ -120,13 +124,13 @@ impl Executor {
pub fn spawn(&self, f: impl Future + 'static) {
// NOTE(unsafe) only safe as long as `spawn` is never re-entered and this does not overlap
// with operation `(A)` (see `Task::block_on`)
self.tasks.lock().push_back(Task::new(f));
self.tasks.borrow_mut().push_back(Task::new(f));
}
}
pub struct Task {
ready: AtomicBool,
f: Box<Future<Output = ()>>,
f: Box<dyn Future<Output = ()>>,
}
impl Task {