task_local context over context objects

- interner impls logically separate from API in orchid-base (default host interner still in base for testing)
- error reporting, logging, and a variety of other features passed down via context in extension, not yet in host to maintain library-ish profile, should consider options
- no global spawn mechanic, the host has a spawn function but extensions only get a stash for enqueuing async work in sync callbacks which is then explicitly, manually, and with strict order popped and awaited
- still deadlocks nondeterministically for some ungodly reason
This commit is contained in:
2026-01-01 14:54:29 +00:00
parent 06debb3636
commit 32d6237dc5
92 changed files with 2507 additions and 2223 deletions

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@@ -6,7 +6,6 @@ edition = "2024"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
async-fn-stream = { version = "0.1.0", path = "../async-fn-stream" }
futures = { version = "0.3.31", features = ["std"], default-features = false }
itertools = "0.14.0"
never = "0.1.0"

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@@ -1,33 +1,44 @@
use std::collections::HashMap;
use std::future::Future;
use std::hash::Hash;
use std::io;
use std::num::NonZero;
use std::ops::{Range, RangeInclusive};
use std::pin::Pin;
use std::rc::Rc;
use std::sync::Arc;
use async_fn_stream::stream;
use futures::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt, StreamExt};
use futures::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
use never::Never;
use ordered_float::NotNan;
use crate::encode_enum;
use crate::{decode_err, decode_err_for, encode_enum, spin_on};
pub trait Decode: 'static {
pub trait Decode: 'static + Sized {
/// Decode an instance from the beginning of the buffer. Return the decoded
/// data and the remaining buffer.
fn decode<R: AsyncRead + ?Sized>(read: Pin<&mut R>) -> impl Future<Output = Self> + '_;
fn decode<R: AsyncRead + ?Sized>(
read: Pin<&mut R>,
) -> impl Future<Output = io::Result<Self>> + '_;
fn decode_slice(slc: &mut &[u8]) -> Self {
spin_on(Self::decode(Pin::new(slc) as Pin<&mut _>)).expect("Decode from slice cannot fail")
}
}
pub trait Encode {
/// Append an instance of the struct to the buffer
fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) -> impl Future<Output = ()>;
fn encode<W: AsyncWrite + ?Sized>(
&self,
write: Pin<&mut W>,
) -> impl Future<Output = io::Result<()>>;
fn encode_vec(&self, vec: &mut Vec<u8>) {
spin_on(self.encode(Pin::new(vec) as Pin<&mut _>)).expect("Encode to vector cannot fail")
}
}
pub trait Coding: Encode + Decode + Clone {
fn get_decoder<T: 'static, F: Future<Output = T> + 'static>(
map: impl Fn(Self) -> F + Clone + 'static,
) -> impl AsyncFn(Pin<&mut dyn AsyncRead>) -> T {
async move |r| map(Self::decode(r).await).await
fn get_decoder<T: 'static>(
map: impl AsyncFn(Self) -> T + Clone + 'static,
) -> impl AsyncFn(Pin<&mut dyn AsyncRead>) -> io::Result<T> {
async move |r| Ok(map(Self::decode(r).await?).await)
}
}
impl<T: Encode + Decode + Clone> Coding for T {}
@@ -35,15 +46,15 @@ impl<T: Encode + Decode + Clone> Coding for T {}
macro_rules! num_impl {
($number:ty) => {
impl Decode for $number {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
let mut bytes = [0u8; (<$number>::BITS / 8) as usize];
read.read_exact(&mut bytes).await.unwrap();
<$number>::from_be_bytes(bytes)
read.read_exact(&mut bytes).await?;
Ok(<$number>::from_be_bytes(bytes))
}
}
impl Encode for $number {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
write.write_all(&self.to_be_bytes()).await.expect("Could not write number")
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
write.write_all(&self.to_be_bytes()).await
}
}
};
@@ -62,12 +73,12 @@ num_impl!(i8);
macro_rules! nonzero_impl {
($name:ty) => {
impl Decode for NonZero<$name> {
async fn decode<R: AsyncRead + ?Sized>(read: Pin<&mut R>) -> Self {
Self::new(<$name as Decode>::decode(read).await).unwrap()
async fn decode<R: AsyncRead + ?Sized>(read: Pin<&mut R>) -> io::Result<Self> {
Self::new(<$name as Decode>::decode(read).await?).ok_or_else(decode_err)
}
}
impl Encode for NonZero<$name> {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) -> io::Result<()> {
self.get().encode(write).await
}
}
@@ -86,22 +97,22 @@ nonzero_impl!(i64);
nonzero_impl!(i128);
impl<T: Encode + ?Sized> Encode for &T {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) -> io::Result<()> {
(**self).encode(write).await
}
}
macro_rules! float_impl {
($t:ty, $size:expr) => {
impl Decode for NotNan<$t> {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
let mut bytes = [0u8; $size];
read.read_exact(&mut bytes).await.unwrap();
NotNan::new(<$t>::from_be_bytes(bytes)).expect("Float was NaN")
read.read_exact(&mut bytes).await?;
NotNan::new(<$t>::from_be_bytes(bytes)).map_err(|_| decode_err())
}
}
impl Encode for NotNan<$t> {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
write.write_all(&self.as_ref().to_be_bytes()).await.expect("Could not write number")
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
write.write_all(&self.as_ref().to_be_bytes()).await
}
}
};
@@ -111,78 +122,77 @@ float_impl!(f64, 8);
float_impl!(f32, 4);
impl Decode for String {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
let len: usize = u64::decode(read.as_mut()).await.try_into().unwrap();
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
let len: usize = u64::decode(read.as_mut()).await?.try_into().map_err(decode_err_for)?;
let mut data = vec![0u8; len];
read.read_exact(&mut data).await.unwrap();
std::str::from_utf8(&data).expect("String invalid UTF-8").to_owned()
read.read_exact(&mut data).await?;
Ok(std::str::from_utf8(&data).map_err(decode_err_for)?.to_owned())
}
}
impl Encode for String {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
u64::try_from(self.len()).unwrap().encode(write.as_mut()).await;
write.write_all(self.as_bytes()).await.unwrap()
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
u64::try_from(self.len()).map_err(decode_err_for)?.encode(write.as_mut()).await?;
write.write_all(self.as_bytes()).await
}
}
impl Encode for str {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
u64::try_from(self.len()).unwrap().encode(write.as_mut()).await;
write.write_all(self.as_bytes()).await.unwrap()
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
u64::try_from(self.len()).map_err(decode_err_for)?.encode(write.as_mut()).await?;
write.write_all(self.as_bytes()).await
}
}
impl<T: Decode> Decode for Vec<T> {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
let len = u64::decode(read.as_mut()).await;
stream(async |mut cx| {
for _ in 0..len {
cx.emit(T::decode(read.as_mut()).await).await
}
})
.collect()
.await
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
let len = u64::decode(read.as_mut()).await?;
let mut values = Vec::with_capacity(len.try_into().map_err(decode_err_for)?);
for _ in 0..len {
values.push(T::decode(read.as_mut()).await?);
}
Ok(values)
}
}
impl<T: Encode> Encode for Vec<T> {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) -> io::Result<()> {
self.as_slice().encode(write).await
}
}
impl<T: Encode> Encode for [T] {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
u64::try_from(self.len()).unwrap().encode(write.as_mut()).await;
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
u64::try_from(self.len()).unwrap().encode(write.as_mut()).await?;
for t in self.iter() {
t.encode(write.as_mut()).await
t.encode(write.as_mut()).await?
}
Ok(())
}
}
impl<T: Decode> Decode for Option<T> {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
match u8::decode(read.as_mut()).await {
0 => None,
1 => Some(T::decode(read).await),
x => panic!("{x} is not a valid option value"),
}
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
Ok(match bool::decode(read.as_mut()).await? {
false => None,
true => Some(T::decode(read).await?),
})
}
}
impl<T: Encode> Encode for Option<T> {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
let t = if let Some(t) = self { t } else { return 0u8.encode(write.as_mut()).await };
1u8.encode(write.as_mut()).await;
t.encode(write).await;
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
self.is_some().encode(write.as_mut()).await?;
if let Some(t) = self {
t.encode(write).await?
}
Ok(())
}
}
impl<T: Decode, E: Decode> Decode for Result<T, E> {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
match u8::decode(read.as_mut()).await {
0 => Self::Ok(T::decode(read).await),
1 => Self::Err(E::decode(read).await),
x => panic!("Invalid Result tag {x}"),
}
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
Ok(match bool::decode(read.as_mut()).await? {
false => Self::Ok(T::decode(read).await?),
true => Self::Err(E::decode(read).await?),
})
}
}
impl<T: Encode, E: Encode> Encode for Result<T, E> {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) -> io::Result<()> {
match self {
Ok(t) => encode_enum(write, 0, |w| t.encode(w)).await,
Err(e) => encode_enum(write, 1, |w| e.encode(w)).await,
@@ -190,36 +200,37 @@ impl<T: Encode, E: Encode> Encode for Result<T, E> {
}
}
impl<K: Decode + Eq + Hash, V: Decode> Decode for HashMap<K, V> {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
let len = u64::decode(read.as_mut()).await;
stream(async |mut cx| {
for _ in 0..len {
cx.emit(<(K, V)>::decode(read.as_mut()).await).await
}
})
.collect()
.await
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
let len = u64::decode(read.as_mut()).await?;
let mut map = HashMap::with_capacity(len.try_into().map_err(decode_err_for)?);
for _ in 0..len {
map.insert(K::decode(read.as_mut()).await?, V::decode(read.as_mut()).await?);
}
Ok(map)
}
}
impl<K: Encode + Eq + Hash, V: Encode> Encode for HashMap<K, V> {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
u64::try_from(self.len()).unwrap().encode(write.as_mut()).await;
for pair in self.iter() {
pair.encode(write.as_mut()).await
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
u64::try_from(self.len()).unwrap().encode(write.as_mut()).await?;
for (key, value) in self.iter() {
key.encode(write.as_mut()).await?;
value.encode(write.as_mut()).await?;
}
Ok(())
}
}
macro_rules! tuple {
(($($t:ident)*) ($($T:ident)*)) => {
impl<$($T: Decode),*> Decode for ($($T,)*) {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
($($T::decode(read.as_mut()).await,)*)
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
Ok(($($T::decode(read.as_mut()).await?,)*))
}
}
impl<$($T: Encode),*> Encode for ($($T,)*) {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
let ($($t,)*) = self;
$( $t.encode(write.as_mut()).await; )*
$( $t.encode(write.as_mut()).await?; )*
Ok(())
}
}
};
@@ -243,63 +254,67 @@ tuple!((t u v x y z a b c d e f g h i) (T U V X Y Z A B C D E F G H I));
tuple!((t u v x y z a b c d e f g h i j) (T U V X Y Z A B C D E F G H I J)); // 16
impl Decode for () {
async fn decode<R: AsyncRead + ?Sized>(_: Pin<&mut R>) -> Self {}
async fn decode<R: AsyncRead + ?Sized>(_: Pin<&mut R>) -> io::Result<Self> { Ok(()) }
}
impl Encode for () {
async fn encode<W: AsyncWrite + ?Sized>(&self, _: Pin<&mut W>) {}
async fn encode<W: AsyncWrite + ?Sized>(&self, _: Pin<&mut W>) -> io::Result<()> { Ok(()) }
}
impl Decode for Never {
async fn decode<R: AsyncRead + ?Sized>(_: Pin<&mut R>) -> Self {
async fn decode<R: AsyncRead + ?Sized>(_: Pin<&mut R>) -> io::Result<Self> {
unreachable!("A value of Never cannot exist so it can't have been serialized");
}
}
impl Encode for Never {
async fn encode<W: AsyncWrite + ?Sized>(&self, _: Pin<&mut W>) { match *self {} }
async fn encode<W: AsyncWrite + ?Sized>(&self, _: Pin<&mut W>) -> io::Result<()> {
match *self {}
}
}
impl Decode for bool {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
let mut buf = [0];
read.read_exact(&mut buf).await.unwrap();
buf[0] != 0
read.read_exact(&mut buf).await?;
Ok(buf[0] != 0)
}
}
impl Encode for bool {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
write.write_all(&[if *self { 0xffu8 } else { 0u8 }]).await.unwrap()
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
write.write_all(&[if *self { 0xffu8 } else { 0u8 }]).await
}
}
impl<T: Decode, const N: usize> Decode for [T; N] {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
let v = stream(async |mut cx| {
for _ in 0..N {
cx.emit(T::decode(read.as_mut()).await).await
}
})
.collect::<Vec<_>>()
.await;
v.try_into().unwrap_or_else(|_| unreachable!("The length of this stream is statically known"))
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
let mut v = Vec::with_capacity(N);
for _ in 0..N {
v.push(T::decode(read.as_mut()).await?);
}
match v.try_into() {
Err(_) => unreachable!("The length of this stream is statically known"),
Ok(arr) => Ok(arr),
}
}
}
impl<T: Encode, const N: usize> Encode for [T; N] {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
for t in self.iter() {
t.encode(write.as_mut()).await
t.encode(write.as_mut()).await?
}
Ok(())
}
}
macro_rules! two_end_range {
($this:ident, $name:tt, $op:tt, $start:expr, $end:expr) => {
impl<T: Decode> Decode for $name<T> {
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> Self {
T::decode(read.as_mut()).await $op T::decode(read).await
async fn decode<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>) -> io::Result<Self> {
Ok(T::decode(read.as_mut()).await? $op T::decode(read).await?)
}
}
impl<T: Encode> Encode for $name<T> {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, mut write: Pin<&mut W>) -> io::Result<()> {
let $this = self;
($start).encode(write.as_mut()).await;
($end).encode(write).await;
($start).encode(write.as_mut()).await?;
($end).encode(write).await?;
Ok(())
}
}
}
@@ -311,12 +326,12 @@ two_end_range!(x, RangeInclusive, ..=, x.start(), x.end());
macro_rules! smart_ptr {
($name:tt) => {
impl<T: Decode> Decode for $name<T> {
async fn decode<R: AsyncRead + ?Sized>(read: Pin<&mut R>) -> Self {
$name::new(T::decode(read).await)
async fn decode<R: AsyncRead + ?Sized>(read: Pin<&mut R>) -> io::Result<Self> {
Ok($name::new(T::decode(read).await?))
}
}
impl<T: Encode> Encode for $name<T> {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) -> io::Result<()> {
(**self).encode(write).await
}
}
@@ -328,12 +343,12 @@ smart_ptr!(Rc);
smart_ptr!(Box);
impl Decode for char {
async fn decode<R: AsyncRead + ?Sized>(read: Pin<&mut R>) -> Self {
char::from_u32(u32::decode(read).await).unwrap()
async fn decode<R: AsyncRead + ?Sized>(read: Pin<&mut R>) -> io::Result<Self> {
char::from_u32(u32::decode(read).await?).ok_or_else(decode_err)
}
}
impl Encode for char {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) {
async fn encode<W: AsyncWrite + ?Sized>(&self, write: Pin<&mut W>) -> io::Result<()> {
(*self as u32).encode(write).await
}
}

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@@ -1,24 +1,24 @@
use std::future::Future;
use std::pin::Pin;
use std::error::Error;
use std::io;
use std::pin::{Pin, pin};
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
use std::task::{Context, Poll, Wake};
use futures::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
use futures::{AsyncRead, AsyncReadExt, AsyncWrite};
use itertools::{Chunk, Itertools};
use crate::Encode;
pub async fn encode_enum<'a, W: AsyncWrite + ?Sized, F: Future<Output = ()>>(
pub async fn encode_enum<'a, W: AsyncWrite + ?Sized>(
mut write: Pin<&'a mut W>,
id: u8,
f: impl FnOnce(Pin<&'a mut W>) -> F,
) {
id.encode(write.as_mut()).await;
f: impl AsyncFnOnce(Pin<&'a mut W>) -> io::Result<()>,
) -> io::Result<()> {
id.encode(write.as_mut()).await?;
f(write).await
}
pub async fn write_exact<W: AsyncWrite + ?Sized>(mut write: Pin<&mut W>, bytes: &'static [u8]) {
write.write_all(bytes).await.expect("Failed to write exact bytes")
}
pub fn print_bytes(b: &[u8]) -> String {
(b.iter().map(|b| format!("{b:02x}")))
.chunks(4)
@@ -27,16 +27,52 @@ pub fn print_bytes(b: &[u8]) -> String {
.join(" ")
}
pub async fn read_exact<R: AsyncRead + ?Sized>(mut read: Pin<&mut R>, bytes: &'static [u8]) {
pub async fn read_exact<R: AsyncRead + ?Sized>(
mut read: Pin<&mut R>,
bytes: &'static [u8],
) -> io::Result<()> {
let mut data = vec![0u8; bytes.len()];
read.read_exact(&mut data).await.expect("Failed to read bytes");
if data != bytes {
panic!("Wrong bytes!\nExpected: {}\nFound: {}", print_bytes(bytes), print_bytes(&data));
read.read_exact(&mut data).await?;
if data == bytes {
Ok(())
} else {
let msg =
format!("Wrong bytes!\nExpected: {}\nFound: {}", print_bytes(bytes), print_bytes(&data));
Err(io::Error::new(io::ErrorKind::InvalidData, msg))
}
}
pub async fn enc_vec(enc: &impl Encode) -> Vec<u8> {
pub fn enc_vec(enc: &impl Encode) -> Vec<u8> {
let mut vec = Vec::new();
enc.encode(Pin::new(&mut vec)).await;
enc.encode_vec(&mut vec);
vec
}
/// Raises a bool flag when called
struct FlagWaker(AtomicBool);
impl Wake for FlagWaker {
fn wake(self: Arc<Self>) { self.0.store(true, Ordering::Relaxed) }
}
pub fn spin_on<F: Future>(fut: F) -> F::Output {
let flag = AtomicBool::new(false);
let flag_waker = Arc::new(FlagWaker(flag));
let mut future = pin!(fut);
loop {
let waker = flag_waker.clone().into();
let mut ctx = Context::from_waker(&waker);
match future.as_mut().poll(&mut ctx) {
// ideally the future should return synchronously
Poll::Ready(res) => break res,
// poorly written futures may yield and immediately wake
Poll::Pending if flag_waker.0.load(Ordering::Relaxed) => (),
// there is no external event to wait for, this has to be a deadlock
Poll::Pending => panic!("Future inside spin_on cannot block"),
};
}
}
pub fn decode_err() -> io::Error { io::Error::new(io::ErrorKind::InvalidData, "Unexpected zero") }
pub fn decode_err_for(e: impl Error) -> io::Error {
io::Error::new(io::ErrorKind::InvalidData, e.to_string())
}

View File

@@ -9,7 +9,7 @@ pub trait Request: fmt::Debug + Sized + 'static {
type Response: fmt::Debug + Coding + 'static;
}
pub async fn respond<R: Request>(_: &R, rep: R::Response) -> Vec<u8> { enc_vec(&rep).await }
pub fn respond<R: Request>(_: &R, rep: R::Response) -> Vec<u8> { enc_vec(&rep) }
pub trait Channel: 'static {
type Req: Coding + Sized + 'static;