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use std::{
io,
os::unix::io::{AsRawFd, RawFd},
pin::Pin,
sync::Arc,
task::{Context, Poll},
};
use futures_core::{ready, Stream};
use tokio::io::unix::AsyncFd;
use crate::events::{Event, EventOwned};
use crate::fd_guard::FdGuard;
use crate::util::read_into_buffer;
#[derive(Debug)]
pub struct EventStream<T> {
fd: AsyncFd<ArcFdGuard>,
buffer: T,
buffer_pos: usize,
unused_bytes: usize,
}
impl<T> EventStream<T>
where
T: AsMut<[u8]> + AsRef<[u8]>,
{
pub(crate) fn new(fd: Arc<FdGuard>, buffer: T) -> io::Result<Self> {
Ok(EventStream {
fd: AsyncFd::new(ArcFdGuard(fd))?,
buffer: buffer,
buffer_pos: 0,
unused_bytes: 0,
})
}
}
impl<T> Stream for EventStream<T>
where
T: AsMut<[u8]> + AsRef<[u8]>,
{
type Item = io::Result<EventOwned>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let self_ = unsafe { self.get_unchecked_mut() };
if self_.unused_bytes == 0 {
self_.buffer_pos = 0;
self_.unused_bytes = ready!(read(&self_.fd, self_.buffer.as_mut(), cx))?;
}
if self_.unused_bytes == 0 {
return Poll::Ready(None);
}
let (bytes_consumed, event) = Event::from_buffer(
Arc::downgrade(&self_.fd.get_ref().0),
&self_.buffer.as_ref()[self_.buffer_pos..],
);
self_.buffer_pos += bytes_consumed;
self_.unused_bytes -= bytes_consumed;
Poll::Ready(Some(Ok(event.into_owned())))
}
}
#[derive(Debug)]
struct ArcFdGuard(Arc<FdGuard>);
impl AsRawFd for ArcFdGuard {
fn as_raw_fd(&self) -> RawFd {
self.0.as_raw_fd()
}
}
fn read(fd: &AsyncFd<ArcFdGuard>, buffer: &mut [u8], cx: &mut Context) -> Poll<io::Result<usize>> {
let mut guard = ready!(fd.poll_read_ready(cx))?;
let result = guard.try_io(|_| {
let read = read_into_buffer(fd.as_raw_fd(), buffer);
if read == -1 {
return Err(io::Error::last_os_error());
}
Ok(read as usize)
});
match result {
Ok(result) => Poll::Ready(result),
Err(_would_block) => {
cx.waker().wake_by_ref();
Poll::Pending
}
}
}