As per Tokio and others, this commit provides a `poll_flush` method on `AsyncWrite` so that a best-effort attempt at wakening once all bytes are flushed can be made.
467: docs: fix some `cargo doc` warnings r=lulf a=numero-744
There are still 3 warnings (below)
```
Documenting embassy v0.1.0 (embassy)
warning: unresolved link to `channel`
--> src/channel/mpsc.rs:241:22
|
241 | /// [`channel`]: channel
| ^^^^^^^ no item named `channel` in scope
|
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
warning: unresolved link to `Task::spawn`
--> src/executor/raw/mod.rs:105:12
|
105 | /// with [`Task::spawn()`], which will fail if it is already spawned.
| ^^^^^^^^^^^^^ no item named `Task` in scope
warning: public documentation for `spawn` links to private item `Executor::spawn`
--> src/executor/raw/mod.rs:156:17
|
156 | /// cause [`Executor::spawn()`] to return the error.
| ^^^^^^^^^^^^^^^^^ this item is private
|
= note: `#[warn(rustdoc::private_intra_doc_links)]` on by default
= note: this link will resolve properly if you pass `--document-private-items`
warning: `embassy` (lib doc) generated 3 warnings
```
Co-authored-by: Côme ALLART <come.allart@etu.emse.fr>
This prevents the std time driver from overflowing when setting the next
wakeup time. If an overflow occurs, default to sleeping up to 1 second.
Fixes#438
428: executor: Use critical sections instead of atomic CAS loops r=lulf a=Dirbaio
Optimize executor wakes.
CAS loops (either `fetch_update`, or manual `load + compare_exchange_weak`) generate surprisingly horrible code: https://godbolt.org/z/zhscnM1cb
This switches to using critical sections, which makes it faster. On thumbv6 (Cortex-M0) it should make it even faster, as it is currently using `atomic-polyfill`, which will make many critical sections for each `compare_exchange_weak` anyway.
```
opt-level=3 opt-level=s
atmics: 105 cycles 101 cycles
CS: 76 cycles 72 cycles
CS+inline: 72 cycles 64 cycles
```
Measured in nrf52 with icache disabled, with this code:
```rust
poll_fn(|cx| {
let task = unsafe { task_from_waker(cx.waker()) };
compiler_fence(Ordering::SeqCst);
let a = cortex_m::peripheral::DWT::get_cycle_count();
compiler_fence(Ordering::SeqCst);
unsafe { wake_task(task) }
compiler_fence(Ordering::SeqCst);
let b = cortex_m::peripheral::DWT::get_cycle_count();
compiler_fence(Ordering::SeqCst);
defmt::info!("cycles: {=u32}", b.wrapping_sub(a));
Poll::Ready(())
})
.await;
````
Co-authored-by: Dario Nieuwenhuis <dirbaio@dirbaio.net>
That steal method has a TAKEN=true write [here](6b013138b7/src/peripheral/mod.rs (L180)).
This is not zero cost, we don't want it. Transmute instead, which is zero cost.
* Adds an executor for WASM runtimes based on wasm_bindgen.
* Add time driver based on JS time handling.
* Add example that can run in browser locally.
* Update to critical-section version that supports 'std' flag
