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Diffstat (limited to 'tokio/src/io/util/read.rs')
-rw-r--r-- | tokio/src/io/util/read.rs | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/tokio/src/io/util/read.rs b/tokio/src/io/util/read.rs new file mode 100644 index 00000000..1fb8c8c8 --- /dev/null +++ b/tokio/src/io/util/read.rs @@ -0,0 +1,53 @@ +use crate::io::AsyncRead; + +use std::future::Future; +use std::io; +use std::marker::Unpin; +use std::pin::Pin; +use std::task::{Context, Poll}; + +/// Tries to read some bytes directly into the given `buf` in asynchronous +/// manner, returning a future type. +/// +/// The returned future will resolve to both the I/O stream and the buffer +/// as well as the number of bytes read once the read operation is completed. +pub(crate) fn read<'a, R>(reader: &'a mut R, buf: &'a mut [u8]) -> Read<'a, R> +where + R: AsyncRead + Unpin + ?Sized, +{ + Read { reader, buf } +} + +/// A future which can be used to easily read available number of bytes to fill +/// a buffer. +/// +/// Created by the [`read`] function. +#[derive(Debug)] +#[must_use = "futures do nothing unless you `.await` or poll them"] +pub struct Read<'a, R: ?Sized> { + reader: &'a mut R, + buf: &'a mut [u8], +} + +impl<R> Future for Read<'_, R> +where + R: AsyncRead + Unpin + ?Sized, +{ + type Output = io::Result<usize>; + + fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<usize>> { + let me = &mut *self; + Pin::new(&mut *me.reader).poll_read(cx, me.buf) + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn assert_unpin() { + use std::marker::PhantomPinned; + crate::is_unpin::<Read<'_, PhantomPinned>>(); + } +} |