mirror of
https://github.com/tokio-rs/tokio.git
synced 2026-08-27 00:00:12 +02:00
95 lines
3.4 KiB
Rust
95 lines
3.4 KiB
Rust
use crate::AsyncRead;
|
|
use std::io;
|
|
use std::ops::DerefMut;
|
|
use std::pin::Pin;
|
|
use std::task::{Context, Poll};
|
|
|
|
/// Read bytes asynchronously.
|
|
///
|
|
/// This trait inherits from `std::io::BufRead` and indicates that an I/O object is
|
|
/// **non-blocking**. All non-blocking I/O objects must return an error when
|
|
/// bytes are unavailable instead of blocking the current thread.
|
|
pub trait AsyncBufRead: AsyncRead {
|
|
/// Attempt to return the contents of the internal buffer, filling it with more data
|
|
/// from the inner reader if it is empty.
|
|
///
|
|
/// On success, returns `Poll::Ready(Ok(buf))`.
|
|
///
|
|
/// If no data is available for reading, the method returns
|
|
/// `Poll::Pending` and arranges for the current task (via
|
|
/// `cx.waker().wake_by_ref()`) to receive a notification when the object becomes
|
|
/// readable or is closed.
|
|
///
|
|
/// This function is a lower-level call. It needs to be paired with the
|
|
/// [`consume`] method to function properly. When calling this
|
|
/// method, none of the contents will be "read" in the sense that later
|
|
/// calling [`poll_read`] may return the same contents. As such, [`consume`] must
|
|
/// be called with the number of bytes that are consumed from this buffer to
|
|
/// ensure that the bytes are never returned twice.
|
|
///
|
|
/// An empty buffer returned indicates that the stream has reached EOF.
|
|
///
|
|
/// [`poll_read`]: AsyncRead::poll_read
|
|
/// [`consume`]: AsyncBufRead::consume
|
|
fn poll_fill_buf<'a>(
|
|
self: Pin<&'a mut Self>,
|
|
cx: &mut Context<'_>,
|
|
) -> Poll<io::Result<&'a [u8]>>;
|
|
|
|
/// Tells this buffer that `amt` bytes have been consumed from the buffer,
|
|
/// so they should no longer be returned in calls to [`poll_read`].
|
|
///
|
|
/// This function is a lower-level call. It needs to be paired with the
|
|
/// [`poll_fill_buf`] method to function properly. This function does
|
|
/// not perform any I/O, it simply informs this object that some amount of
|
|
/// its buffer, returned from [`poll_fill_buf`], has been consumed and should
|
|
/// no longer be returned. As such, this function may do odd things if
|
|
/// [`poll_fill_buf`] isn't called before calling it.
|
|
///
|
|
/// The `amt` must be `<=` the number of bytes in the buffer returned by
|
|
/// [`poll_fill_buf`].
|
|
///
|
|
/// [`poll_read`]: AsyncRead::poll_read
|
|
/// [`poll_fill_buf`]: AsyncBufRead::poll_fill_buf
|
|
fn consume(self: Pin<&mut Self>, amt: usize);
|
|
}
|
|
|
|
macro_rules! deref_async_buf_read {
|
|
() => {
|
|
fn poll_fill_buf<'a>(self: Pin<&'a mut Self>, cx: &mut Context<'_>)
|
|
-> Poll<io::Result<&'a [u8]>>
|
|
{
|
|
Pin::new(&mut **self.get_mut()).poll_fill_buf(cx)
|
|
}
|
|
|
|
fn consume(mut self: Pin<&mut Self>, amt: usize) {
|
|
Pin::new(&mut **self).consume(amt)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: ?Sized + AsyncBufRead + Unpin> AsyncBufRead for Box<T> {
|
|
deref_async_buf_read!();
|
|
}
|
|
|
|
impl<T: ?Sized + AsyncBufRead + Unpin> AsyncBufRead for &mut T {
|
|
deref_async_buf_read!();
|
|
}
|
|
|
|
impl<P> AsyncBufRead for Pin<P>
|
|
where
|
|
P: DerefMut + Unpin,
|
|
P::Target: AsyncBufRead,
|
|
{
|
|
fn poll_fill_buf<'a>(
|
|
self: Pin<&'a mut Self>,
|
|
cx: &mut Context<'_>,
|
|
) -> Poll<io::Result<&'a [u8]>> {
|
|
self.get_mut().as_mut().poll_fill_buf(cx)
|
|
}
|
|
|
|
fn consume(self: Pin<&mut Self>, amt: usize) {
|
|
self.get_mut().as_mut().consume(amt)
|
|
}
|
|
}
|