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use crate::task::{self as task03, ArcWake as ArcWake03, WakerRef};
use futures_01::{
task as task01, Async as Async01, Future as Future01, Poll as Poll01, Stream as Stream01,
};
#[cfg(feature = "sink")]
use futures_01::{AsyncSink as AsyncSink01, Sink as Sink01, StartSend as StartSend01};
use futures_core::{
future::TryFuture as TryFuture03,
stream::TryStream as TryStream03,
task::{RawWaker, RawWakerVTable},
};
#[cfg(feature = "sink")]
use futures_sink::Sink as Sink03;
#[cfg(feature = "sink")]
use std::marker::PhantomData;
use std::{mem, pin::Pin, sync::Arc, task::Context};
/// Converts a futures 0.3 [`TryFuture`](futures_core::future::TryFuture) or
/// [`TryStream`](futures_core::stream::TryStream) into a futures 0.1
/// [`Future`](futures_01::future::Future) or
/// [`Stream`](futures_01::stream::Stream).
#[derive(Debug, Clone, Copy)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct Compat<T> {
pub(crate) inner: T,
}
/// Converts a futures 0.3 [`Sink`](futures_sink::Sink) into a futures 0.1
/// [`Sink`](futures_01::sink::Sink).
#[cfg(feature = "sink")]
#[cfg_attr(docsrs, doc(cfg(feature = "sink")))]
#[derive(Debug)]
#[must_use = "sinks do nothing unless polled"]
pub struct CompatSink<T, Item> {
inner: T,
_phantom: PhantomData<fn(Item)>,
}
impl<T> Compat<T> {
/// Creates a new [`Compat`].
///
/// For types which implement appropriate futures `0.3`
/// traits, the result will be a type which implements
/// the corresponding futures 0.1 type.
pub fn new(inner: T) -> Self {
Self { inner }
}
/// Get a reference to 0.3 Future, Stream, AsyncRead, or AsyncWrite object
/// contained within.
pub fn get_ref(&self) -> &T {
&self.inner
}
/// Get a mutable reference to 0.3 Future, Stream, AsyncRead, or AsyncWrite object
/// contained within.
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
/// Returns the inner item.
pub fn into_inner(self) -> T {
self.inner
}
}
#[cfg(feature = "sink")]
impl<T, Item> CompatSink<T, Item> {
/// Creates a new [`CompatSink`].
pub fn new(inner: T) -> Self {
Self { inner, _phantom: PhantomData }
}
/// Get a reference to 0.3 Sink contained within.
pub fn get_ref(&self) -> &T {
&self.inner
}
/// Get a mutable reference to 0.3 Sink contained within.
pub fn get_mut(&mut self) -> &mut T {
&mut self.inner
}
/// Returns the inner item.
pub fn into_inner(self) -> T {
self.inner
}
}
fn poll_03_to_01<T, E>(x: task03::Poll<Result<T, E>>) -> Result<Async01<T>, E> {
match x? {
task03::Poll::Ready(t) => Ok(Async01::Ready(t)),
task03::Poll::Pending => Ok(Async01::NotReady),
}
}
impl<Fut> Future01 for Compat<Fut>
where
Fut: TryFuture03 + Unpin,
{
type Item = Fut::Ok;
type Error = Fut::Error;
fn poll(&mut self) -> Poll01<Self::Item, Self::Error> {
with_context(self, |inner, cx| poll_03_to_01(inner.try_poll(cx)))
}
}
impl<St> Stream01 for Compat<St>
where
St: TryStream03 + Unpin,
{
type Item = St::Ok;
type Error = St::Error;
fn poll(&mut self) -> Poll01<Option<Self::Item>, Self::Error> {
with_context(self, |inner, cx| match inner.try_poll_next(cx)? {
task03::Poll::Ready(None) => Ok(Async01::Ready(None)),
task03::Poll::Ready(Some(t)) => Ok(Async01::Ready(Some(t))),
task03::Poll::Pending => Ok(Async01::NotReady),
})
}
}
#[cfg(feature = "sink")]
impl<T, Item> Sink01 for CompatSink<T, Item>
where
T: Sink03<Item> + Unpin,
{
type SinkItem = Item;
type SinkError = T::Error;
fn start_send(&mut self, item: Self::SinkItem) -> StartSend01<Self::SinkItem, Self::SinkError> {
with_sink_context(self, |mut inner, cx| match inner.as_mut().poll_ready(cx)? {
task03::Poll::Ready(()) => inner.start_send(item).map(|()| AsyncSink01::Ready),
task03::Poll::Pending => Ok(AsyncSink01::NotReady(item)),
})
}
fn poll_complete(&mut self) -> Poll01<(), Self::SinkError> {
with_sink_context(self, |inner, cx| poll_03_to_01(inner.poll_flush(cx)))
}
fn close(&mut self) -> Poll01<(), Self::SinkError> {
with_sink_context(self, |inner, cx| poll_03_to_01(inner.poll_close(cx)))
}
}
#[derive(Clone)]
struct Current(task01::Task);
impl Current {
fn new() -> Self {
Self(task01::current())
}
fn as_waker(&self) -> WakerRef<'_> {
unsafe fn ptr_to_current<'a>(ptr: *const ()) -> &'a Current {
&*(ptr as *const Current)
}
fn current_to_ptr(current: &Current) -> *const () {
current as *const Current as *const ()
}
unsafe fn clone(ptr: *const ()) -> RawWaker {
// Lazily create the `Arc` only when the waker is actually cloned.
// FIXME: remove `transmute` when a `Waker` -> `RawWaker` conversion
// function is landed in `core`.
mem::transmute::<task03::Waker, RawWaker>(task03::waker(Arc::new(
ptr_to_current(ptr).clone(),
)))
}
unsafe fn drop(_: *const ()) {}
unsafe fn wake(ptr: *const ()) {
ptr_to_current(ptr).0.notify()
}
let ptr = current_to_ptr(self);
let vtable = &RawWakerVTable::new(clone, wake, wake, drop);
WakerRef::new_unowned(std::mem::ManuallyDrop::new(unsafe {
task03::Waker::from_raw(RawWaker::new(ptr, vtable))
}))
}
}
impl ArcWake03 for Current {
fn wake_by_ref(arc_self: &Arc<Self>) {
arc_self.0.notify();
}
}
fn with_context<T, R, F>(compat: &mut Compat<T>, f: F) -> R
where
T: Unpin,
F: FnOnce(Pin<&mut T>, &mut Context<'_>) -> R,
{
let current = Current::new();
let waker = current.as_waker();
let mut cx = Context::from_waker(&waker);
f(Pin::new(&mut compat.inner), &mut cx)
}
#[cfg(feature = "sink")]
fn with_sink_context<T, Item, R, F>(compat: &mut CompatSink<T, Item>, f: F) -> R
where
T: Unpin,
F: FnOnce(Pin<&mut T>, &mut Context<'_>) -> R,
{
let current = Current::new();
let waker = current.as_waker();
let mut cx = Context::from_waker(&waker);
f(Pin::new(&mut compat.inner), &mut cx)
}
#[cfg(feature = "io-compat")]
#[cfg_attr(docsrs, doc(cfg(feature = "io-compat")))]
mod io {
use super::*;
use futures_io::{AsyncRead as AsyncRead03, AsyncWrite as AsyncWrite03};
use tokio_io::{AsyncRead as AsyncRead01, AsyncWrite as AsyncWrite01};
fn poll_03_to_io<T>(x: task03::Poll<Result<T, std::io::Error>>) -> Result<T, std::io::Error> {
match x {
task03::Poll::Ready(Ok(t)) => Ok(t),
task03::Poll::Pending => Err(std::io::ErrorKind::WouldBlock.into()),
task03::Poll::Ready(Err(e)) => Err(e),
}
}
impl<R: AsyncRead03 + Unpin> std::io::Read for Compat<R> {
fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
let current = Current::new();
let waker = current.as_waker();
let mut cx = Context::from_waker(&waker);
poll_03_to_io(Pin::new(&mut self.inner).poll_read(&mut cx, buf))
}
}
impl<R: AsyncRead03 + Unpin> AsyncRead01 for Compat<R> {}
impl<W: AsyncWrite03 + Unpin> std::io::Write for Compat<W> {
fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
let current = Current::new();
let waker = current.as_waker();
let mut cx = Context::from_waker(&waker);
poll_03_to_io(Pin::new(&mut self.inner).poll_write(&mut cx, buf))
}
fn flush(&mut self) -> std::io::Result<()> {
let current = Current::new();
let waker = current.as_waker();
let mut cx = Context::from_waker(&waker);
poll_03_to_io(Pin::new(&mut self.inner).poll_flush(&mut cx))
}
}
impl<W: AsyncWrite03 + Unpin> AsyncWrite01 for Compat<W> {
fn shutdown(&mut self) -> std::io::Result<Async01<()>> {
let current = Current::new();
let waker = current.as_waker();
let mut cx = Context::from_waker(&waker);
poll_03_to_01(Pin::new(&mut self.inner).poll_close(&mut cx))
}
}
}