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use bytes::{Buf, IntoBuf};
use futures::{Async, AsyncSink, Poll, Sink, Stream};
use std::cmp;
use std::io::Error as IoError;
use std::io::ErrorKind as IoErrorKind;
use std::io::{Read, Write};
use tokio_io::{AsyncRead, AsyncWrite};
pub struct RwStreamSink<S>
where
S: Stream,
S::Item: IntoBuf,
{
inner: S,
current_item: Option<<S::Item as IntoBuf>::Buf>,
}
impl<S> RwStreamSink<S>
where
S: Stream,
S::Item: IntoBuf,
{
#[inline]
pub fn new(inner: S) -> RwStreamSink<S> {
RwStreamSink { inner, current_item: None }
}
}
impl<S> Read for RwStreamSink<S>
where
S: Stream<Error = IoError>,
S::Item: IntoBuf,
{
fn read(&mut self, buf: &mut [u8]) -> Result<usize, IoError> {
let item_to_copy = loop {
if let Some(ref mut i) = self.current_item {
if i.has_remaining() {
break i;
}
}
self.current_item = Some(match self.inner.poll()? {
Async::Ready(Some(i)) => i.into_buf(),
Async::Ready(None) => return Ok(0),
Async::NotReady => return Err(IoErrorKind::WouldBlock.into()),
});
};
debug_assert!(item_to_copy.has_remaining());
let to_copy = cmp::min(buf.len(), item_to_copy.remaining());
item_to_copy.take(to_copy).copy_to_slice(&mut buf[..to_copy]);
Ok(to_copy)
}
}
impl<S> AsyncRead for RwStreamSink<S>
where
S: Stream<Error = IoError>,
S::Item: IntoBuf,
{
}
impl<S> Write for RwStreamSink<S>
where
S: Stream + Sink<SinkError = IoError>,
S::SinkItem: for<'r> From<&'r [u8]>,
S::Item: IntoBuf,
{
#[inline]
fn write(&mut self, buf: &[u8]) -> Result<usize, IoError> {
let len = buf.len();
match self.inner.start_send(buf.into())? {
AsyncSink::Ready => Ok(len),
AsyncSink::NotReady(_) => Err(IoError::new(IoErrorKind::WouldBlock, "not ready")),
}
}
#[inline]
fn flush(&mut self) -> Result<(), IoError> {
match self.inner.poll_complete()? {
Async::Ready(()) => Ok(()),
Async::NotReady => Err(IoError::new(IoErrorKind::WouldBlock, "not ready"))
}
}
}
impl<S> AsyncWrite for RwStreamSink<S>
where
S: Stream + Sink<SinkError = IoError>,
S::SinkItem: for<'r> From<&'r [u8]>,
S::Item: IntoBuf,
{
#[inline]
fn shutdown(&mut self) -> Poll<(), IoError> {
self.inner.close()
}
}
#[cfg(test)]
mod tests {
use bytes::Bytes;
use crate::RwStreamSink;
use futures::{prelude::*, stream, sync::mpsc::channel};
use std::io::Read;
struct Wrapper<St, Si>(St, Si);
impl<St, Si> Stream for Wrapper<St, Si>
where
St: Stream,
{
type Item = St::Item;
type Error = St::Error;
fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
self.0.poll()
}
}
impl<St, Si> Sink for Wrapper<St, Si>
where
Si: Sink,
{
type SinkItem = Si::SinkItem;
type SinkError = Si::SinkError;
fn start_send(
&mut self,
item: Self::SinkItem,
) -> StartSend<Self::SinkItem, Self::SinkError> {
self.1.start_send(item)
}
fn poll_complete(&mut self) -> Poll<(), Self::SinkError> {
self.1.poll_complete()
}
fn close(&mut self) -> Poll<(), Self::SinkError> {
self.1.close()
}
}
#[test]
fn basic_reading() {
let (tx1, _) = channel::<Vec<u8>>(10);
let (tx2, rx2) = channel(10);
let mut wrapper = RwStreamSink::new(Wrapper(rx2.map_err(|_| panic!()), tx1));
tx2.send(Bytes::from("hel"))
.and_then(|tx| tx.send(Bytes::from("lo wor")))
.and_then(|tx| tx.send(Bytes::from("ld")))
.wait()
.unwrap();
let mut data = Vec::new();
wrapper.read_to_end(&mut data).unwrap();
assert_eq!(data, b"hello world");
}
#[test]
fn skip_empty_stream_items() {
let data: Vec<&[u8]> = vec![b"", b"foo", b"", b"bar", b"", b"baz", b""];
let mut rws = RwStreamSink::new(stream::iter_ok::<_, std::io::Error>(data));
let mut buf = [0; 9];
assert_eq!(3, rws.read(&mut buf).unwrap());
assert_eq!(3, rws.read(&mut buf[3..]).unwrap());
assert_eq!(3, rws.read(&mut buf[6..]).unwrap());
assert_eq!(0, rws.read(&mut buf).unwrap());
assert_eq!(b"foobarbaz", &buf[..]);
}
#[test]
fn partial_read() {
let data: Vec<&[u8]> = vec![b"hell", b"o world"];
let mut rws = RwStreamSink::new(stream::iter_ok::<_, std::io::Error>(data));
let mut buf = [0; 3];
assert_eq!(3, rws.read(&mut buf).unwrap());
assert_eq!(b"hel", &buf[..3]);
assert_eq!(0, rws.read(&mut buf[..0]).unwrap());
assert_eq!(1, rws.read(&mut buf).unwrap());
assert_eq!(b"l", &buf[..1]);
assert_eq!(3, rws.read(&mut buf).unwrap());
assert_eq!(b"o w", &buf[..3]);
assert_eq!(0, rws.read(&mut buf[..0]).unwrap());
assert_eq!(3, rws.read(&mut buf).unwrap());
assert_eq!(b"orl", &buf[..3]);
assert_eq!(1, rws.read(&mut buf).unwrap());
assert_eq!(b"d", &buf[..1]);
assert_eq!(0, rws.read(&mut buf).unwrap());
}
}