mirror of
https://github.com/tokio-rs/tokio.git
synced 2026-09-08 00:00:13 +02:00
Carl Lerche
b479ce78d3
This patch adds experimental async/await support to Tokio. It does this by adding feature flags to existing libs only where necessary in order to add nightly specific code (mostly `Unpin` implementations). It then provides a new crate: `tokio-async-await` which is a shim layer on top of `tokio`. The `tokio-async-await` crate is expected to look exactly like `tokio` does, but with async / await support. This strategy reduces the amount of cfg guarding in the main libraries. This patch also adds `tokio-channel`, which is copied from futures-rs 0.1 and adds the necessary `Unpin` implementations. In general, futures 0.1 is mostly unmaintained, so it will make sense for Tokio to take over maintainership of key components regardless of async / await support.
57 lines
1.4 KiB
Rust
57 lines
1.4 KiB
Rust
use tokio_io::AsyncRead;
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use futures_core::future::Future;
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use futures_core::task::{self, Poll};
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use futures_util::try_ready;
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use std::io;
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use std::marker::Unpin;
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use std::mem::{self, PinMut};
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/// A future which can be used to read exactly enough bytes to fill a buffer.
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#[derive(Debug)]
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pub struct ReadExact<'a, T: ?Sized + 'a> {
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reader: &'a mut T,
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buf: &'a mut [u8],
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}
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// Pinning is never projected to fields
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impl<'a, T: ?Sized> Unpin for ReadExact<'a, T> {}
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impl<'a, T: AsyncRead + ?Sized> ReadExact<'a, T> {
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pub(super) fn new(reader: &'a mut T, buf: &'a mut [u8]) -> ReadExact<'a, T> {
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ReadExact {
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reader,
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buf,
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}
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}
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}
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fn eof() -> io::Error {
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io::Error::new(io::ErrorKind::UnexpectedEof, "early eof")
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}
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impl<'a, T: AsyncRead + ?Sized> Future for ReadExact<'a, T> {
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type Output = io::Result<()>;
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fn poll(mut self: PinMut<Self>, _cx: &mut task::Context) -> Poll<Self::Output> {
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use crate::async_await::compat::forward::convert_poll;
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let this = &mut *self;
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while !this.buf.is_empty() {
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let n = try_ready!(convert_poll(this.reader.poll_read(this.buf)));
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{
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let (_, rest) = mem::replace(&mut this.buf, &mut []).split_at_mut(n);
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this.buf = rest;
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}
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if n == 0 {
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return Poll::Ready(Err(eof()))
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}
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}
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Poll::Ready(Ok(()))
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}
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}
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