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use BufStream;
use bytes::Buf;
use futures::Poll;
#[derive(Debug)]
pub struct Limit<T> {
stream: T,
remaining: u64,
}
#[derive(Debug)]
pub struct LimitError<T> {
inner: Option<T>,
}
impl<T> Limit<T> {
pub(crate) fn new(stream: T, amount: u64) -> Limit<T> {
Limit {
stream,
remaining: amount,
}
}
}
impl<T> BufStream for Limit<T>
where
T: BufStream,
{
type Item = T::Item;
type Error = LimitError<T::Error>;
fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
use futures::Async::Ready;
if self.stream.size_hint().lower() > self.remaining {
return Err(LimitError { inner: None });
}
let res = self
.stream
.poll_buf()
.map_err(|err| LimitError { inner: Some(err) });
match res {
Ok(Ready(Some(ref buf))) => {
if buf.remaining() as u64 > self.remaining {
self.remaining = 0;
return Err(LimitError { inner: None });
}
self.remaining -= buf.remaining() as u64;
}
_ => {}
}
res
}
}
impl<T> LimitError<T> {
pub fn is_stream_err(&self) -> bool {
self.inner.is_some()
}
pub fn is_limit_err(&self) -> bool {
self.inner.is_none()
}
}