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

orchid-api-traits/src/helpers.rs

@@ -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())
+}