feat: migrate integration crate off-tree

Signed-off-by: Enzo "raskyld" Nocera <[email protected]>

Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "leptos_wasi"
+authors = ["Enzo Nocera"]
+license = "MIT"
+repository = "https://github.com/leptos-rs/leptos_wasi"
+description = "WASI integrations for the Leptos web framework."
+version = "0.0.0"
+edition = "2021"
+
+[dependencies]
+any_spawner = { version = "0.1.1", features = ["futures-executor"] }
+throw_error = { version = "0.2.0-rc0" }
+hydration_context = { version = "0.2.0-rc0" }
+futures = "0.3.30"
+wasi = "0.13.1+wasi-0.2.0"
+leptos = { version = "0.7.0-rc0", features = ["nonce", "ssr"] }
+leptos_meta = { version = "0.7.0-rc0", features = ["ssr"] }
+leptos_router = { version = "0.7.0-rc0", features = ["ssr"] }
+leptos_macro = { version = "0.7.0-rc0", features = ["generic"] }
+leptos_integration_utils = {version = "0.7.0-rc0" }
+server_fn = { version = "0.7.0-rc0", features = ["generic"] }
+http = "1.1.0"
+parking_lot = "0.12.3"
+bytes = "1.7.2"
+routefinder = "0.5.4"
+mime_guess = "2.0"
+thiserror = "1.0.65"

src/executor.rs

@@ -0,0 +1,280 @@
+//! This is (Yet Another) Async Runtime for WASI with first-class support
+//! for `.await`-ing on [`Pollable`]. It is an ad-hoc implementation
+//! tailored for Leptos but it could be exported into a standalone crate.
+//!
+//! It is based on the `futures` crate's [`LocalPool`] and makes use of
+//! no `unsafe` code.
+//!
+//! # Performance Notes
+//!
+//! I haven't benchmarked this runtime but since it makes no use of unsafe code
+//! and Rust `core`'s `Context` was prematurely optimised for multi-threading
+//! environment, I had no choice but using synchronisation primitives to make
+//! the API happy.
+//!
+//! IIRC, `wasm32` targets have an implementation of synchronisation primitives
+//! that are just stubs, downgrading them to their single-threaded counterpart
+//! so the overhead should be minimal.
+//!
+//! Also, you can customise the behaviour of the [`Executor`] using the
+//! [`Mode`] enum to trade-off reactivity for less host context switch
+//! with the [`Mode::Stalled`] variant.
+
+use std::{
+    cell::RefCell,
+    future::Future,
+    mem,
+    rc::Rc,
+    sync::{Arc, OnceLock},
+    task::{Context, Poll, Wake, Waker},
+};
+
+use any_spawner::CustomExecutor;
+use futures::{
+    channel::mpsc::{UnboundedReceiver, UnboundedSender},
+    executor::{LocalPool, LocalSpawner},
+    task::{LocalSpawnExt, SpawnExt},
+    FutureExt, Stream,
+};
+use parking_lot::Mutex;
+use wasi::{
+    clocks::monotonic_clock::{subscribe_duration, Duration},
+    io::poll::{poll, Pollable},
+};
+
+struct TableEntry(Pollable, Waker);
+
+static POLLABLE_SINK: OnceLock<UnboundedSender<TableEntry>> = OnceLock::new();
+
+pub async fn sleep(duration: Duration) {
+    WaitPoll::new(subscribe_duration(duration)).await
+}
+
+pub struct WaitPoll(WaitPollInner);
+
+enum WaitPollInner {
+    Unregistered(Pollable),
+    Registered(Arc<WaitPollWaker>),
+}
+
+impl WaitPoll {
+    pub fn new(pollable: Pollable) -> Self {
+        Self(WaitPollInner::Unregistered(pollable))
+    }
+}
+
+impl Future for WaitPoll {
+    type Output = ();
+
+    fn poll(
+        self: std::pin::Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Self::Output> {
+        match &mut self.get_mut().0 {
+            this @ WaitPollInner::Unregistered(_) => {
+                let waker = Arc::new(WaitPollWaker::new(cx.waker()));
+
+                if let Some(sender) = POLLABLE_SINK.get() {
+                    if let WaitPollInner::Unregistered(pollable) = mem::replace(
+                        this,
+                        WaitPollInner::Registered(waker.clone()),
+                    ) {
+                        sender
+                            .clone()
+                            .unbounded_send(TableEntry(pollable, waker.into()))
+                            .expect("cannot spawn a new WaitPoll");
+
+                        Poll::Pending
+                    } else {
+                        unreachable!();
+                    }
+                } else {
+                    panic!(
+                        "cannot create a WaitPoll before creating an Executor"
+                    );
+                }
+            }
+            WaitPollInner::Registered(waker) => {
+                let mut lock = waker.0.lock();
+                if lock.done {
+                    Poll::Ready(())
+                } else {
+                    // How can it happen?! :O
+                    // Well, if, for some reason, the Task get woken up for
+                    // another reason than the pollable associated with this
+                    // WaitPoll got ready.
+                    //
+                    // We need to make sure we update the waker.
+                    lock.task_waker = cx.waker().clone();
+                    Poll::Pending
+                }
+            }
+        }
+    }
+}
+
+struct WaitPollWaker(Mutex<WaitPollWakerInner>);
+
+struct WaitPollWakerInner {
+    done: bool,
+    task_waker: Waker,
+}
+
+impl WaitPollWaker {
+    fn new(waker: &Waker) -> Self {
+        Self(Mutex::new(WaitPollWakerInner {
+            done: false,
+            task_waker: waker.clone(),
+        }))
+    }
+}
+
+impl Wake for WaitPollWaker {
+    fn wake(self: std::sync::Arc<Self>) {
+        self.wake_by_ref();
+    }
+
+    fn wake_by_ref(self: &std::sync::Arc<Self>) {
+        let mut lock = self.0.lock();
+        lock.task_waker.wake_by_ref();
+        lock.done = true;
+    }
+}
+
+/// Controls how often the [`Executor`] checks for [`Pollable`] readiness.
+pub enum Mode {
+    /// Will check as often as possible for readiness, this have some
+    /// performance overhead.
+    Premptive,
+
+    /// Will only check for readiness when no more progress can be made
+    /// on pooled Futures.
+    Stalled,
+}
+
+#[derive(Clone)]
+pub struct Executor(Rc<ExecutorInner>);
+
+struct ExecutorInner {
+    pool: RefCell<LocalPool>,
+    spawner: LocalSpawner,
+    rx: RefCell<UnboundedReceiver<TableEntry>>,
+    mode: Mode,
+}
+
+impl Executor {
+    pub fn new(mode: Mode) -> Self {
+        let pool = LocalPool::new();
+        let spawner = pool.spawner();
+        let (tx, rx) = futures::channel::mpsc::unbounded();
+
+        POLLABLE_SINK
+            .set(tx.clone())
+            .expect("calling Executor::new two times is not supported");
+
+        Self(Rc::new(ExecutorInner {
+            pool: RefCell::new(pool),
+            spawner,
+            rx: RefCell::new(rx),
+            mode,
+        }))
+    }
+
+    pub fn run_until<T>(&self, fut: T) -> T::Output
+    where
+        T: Future + 'static,
+    {
+        let (tx, mut rx) = futures::channel::oneshot::channel::<T::Output>();
+        self.spawn_local(Box::pin(fut.then(|val| async move {
+            if tx.send(val).is_err() {
+                panic!("failed to send the return value of the future passed to run_until");
+            }
+        })));
+
+        loop {
+            match rx.try_recv() {
+                Err(_) => panic!(
+                    "internal error: sender of run until has been dropped"
+                ),
+                Ok(Some(val)) => return val,
+                Ok(None) => {
+                    self.poll_local();
+                }
+            }
+        }
+    }
+}
+
+impl CustomExecutor for Executor {
+    fn spawn(&self, fut: any_spawner::PinnedFuture<()>) {
+        self.0.spawner.spawn(fut).unwrap();
+    }
+
+    fn spawn_local(&self, fut: any_spawner::PinnedLocalFuture<()>) {
+        self.0.spawner.spawn_local(fut).unwrap();
+    }
+
+    fn poll_local(&self) {
+        let mut pool = match self.0.pool.try_borrow_mut() {
+            Ok(pool) => pool,
+            // Nested call to poll_local(), noop.
+            Err(_) => return,
+        };
+
+        match self.0.mode {
+            Mode::Premptive => {
+                pool.try_run_one();
+            }
+            Mode::Stalled => pool.run_until_stalled(),
+        };
+
+        let (lower, upper) = self.0.rx.borrow().size_hint();
+        let capacity = upper.unwrap_or(lower);
+        let mut entries = Vec::with_capacity(capacity);
+        let mut rx = self.0.rx.borrow_mut();
+
+        loop {
+            match rx.try_next() {
+                Ok(None) => break,
+                Ok(Some(entry)) => {
+                    entries.push(Some(entry));
+                }
+                Err(_) => break,
+            }
+        }
+
+        if entries.is_empty() {
+            // This could happen if some Futures use Waker that are not
+            // registered through [`WaitPoll`] or that we are blocked
+            // because some Future returned `Poll::Pending` without
+            // actually making sure their Waker is called at some point.
+            return;
+        }
+
+        let pollables = entries
+            .iter()
+            .map(|entry| &entry.as_ref().unwrap().0)
+            .collect::<Vec<_>>();
+
+        let ready = poll(&pollables);
+
+        if let Some(sender) = POLLABLE_SINK.get() {
+            let sender = sender.clone();
+
+            // Wakes futures subscribed to ready pollable.
+            for index in ready {
+                let wake = entries[index as usize].take().unwrap().1;
+                wake.wake();
+            }
+
+            // Requeue not ready pollable.
+            for entry in entries.into_iter().flatten() {
+                sender
+                    .unbounded_send(entry)
+                    .expect("the sender channel is closed");
+            }
+        } else {
+            unreachable!();
+        }
+    }
+}