use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
use crate::VsockStream;
use futures::ready;
use std::fmt;
use std::io;
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};
pub fn split(stream: &mut VsockStream) -> (ReadHalf<'_>, WriteHalf<'_>) {
(ReadHalf(stream), WriteHalf(stream))
}
pub struct ReadHalf<'a>(&'a VsockStream);
pub struct WriteHalf<'a>(&'a VsockStream);
impl AsyncRead for ReadHalf<'_> {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
self.0.poll_read_priv(cx, buf)
}
}
impl AsyncWrite for WriteHalf<'_> {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<Result<usize, io::Error>> {
self.0.poll_write_priv(cx, buf)
}
#[inline]
fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
Poll::Ready(Ok(()))
}
fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
self.0.shutdown(std::net::Shutdown::Write)?;
Poll::Ready(Ok(()))
}
}
pub fn split_owned(stream: VsockStream) -> (OwnedReadHalf, OwnedWriteHalf) {
let inner = Arc::new(Inner::new(stream));
let rd = OwnedReadHalf {
inner: inner.clone(),
};
let wr = OwnedWriteHalf { inner };
(rd, wr)
}
pub struct OwnedReadHalf {
inner: Arc<Inner>,
}
pub struct OwnedWriteHalf {
inner: Arc<Inner>,
}
struct Inner(tokio::sync::Mutex<VsockStream>);
impl Inner {
fn new(stream: VsockStream) -> Self {
Self(tokio::sync::Mutex::new(stream))
}
}
struct Guard<'a>(tokio::sync::MutexGuard<'a, VsockStream>);
impl OwnedReadHalf {
pub fn is_pair_of(&self, other: &OwnedWriteHalf) -> bool {
other.is_pair_of(self)
}
#[track_caller]
pub fn unsplit(self, wr: OwnedWriteHalf) -> VsockStream {
if self.is_pair_of(&wr) {
drop(wr);
let inner = Arc::try_unwrap(self.inner)
.ok()
.expect("`Arc::try_unwrap` failed");
inner.0.into_inner()
} else {
panic!("Unrelated `split::Write` passed to `split::Read::unsplit`.")
}
}
}
impl OwnedWriteHalf {
pub fn is_pair_of(&self, other: &OwnedReadHalf) -> bool {
Arc::ptr_eq(&self.inner, &other.inner)
}
}
impl AsyncRead for OwnedReadHalf {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
let mut inner = ready!(self.inner.poll_lock(cx));
inner.stream_pin().poll_read(cx, buf)
}
}
impl AsyncWrite for OwnedWriteHalf {
fn poll_write(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<Result<usize, io::Error>> {
let mut inner = ready!(self.inner.poll_lock(cx));
inner.stream_pin().poll_write(cx, buf)
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
let mut inner = ready!(self.inner.poll_lock(cx));
inner.stream_pin().poll_flush(cx)
}
fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
let mut inner = ready!(self.inner.poll_lock(cx));
inner.stream_pin().poll_shutdown(cx)
}
}
impl Inner {
fn poll_lock(&self, cx: &mut Context<'_>) -> Poll<Guard<'_>> {
if let Ok(guard) = self.0.try_lock() {
Poll::Ready(Guard(guard))
} else {
std::thread::yield_now();
cx.waker().wake_by_ref();
Poll::Pending
}
}
}
impl Guard<'_> {
fn stream_pin(&mut self) -> Pin<&mut VsockStream> {
unsafe { Pin::new_unchecked(&mut *self.0) }
}
}
impl fmt::Debug for OwnedReadHalf {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("split::OwnedReadHalf").finish()
}
}
impl fmt::Debug for OwnedWriteHalf {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("split::OwnedWriteHalf").finish()
}
}
impl fmt::Debug for ReadHalf<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("split::ReadHalf").finish()
}
}
impl fmt::Debug for WriteHalf<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("split::WriteHalf").finish()
}
}