74 lines
2.3 KiB
Rust
74 lines
2.3 KiB
Rust
// Copyright 2015-2018 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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//! A chunk-producing io::Read wrapper.
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use std::io::{self, Read};
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use futures::{self, sink, Sink, Future};
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use futures::sync::mpsc;
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use hyper;
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type Sender = mpsc::Sender<Result<hyper::Chunk, hyper::Error>>;
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const MAX_CHUNK_SIZE: usize = 32 * 1024;
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/// A Reader is essentially a stream of `hyper::Chunks`.
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/// The chunks are read from given `io::Read` instance.
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///
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/// Unfortunately `hyper` doesn't allow you to pass `Stream`
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/// directly to the response, so you need to create
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/// a `Body::pair()` and send over chunks using `sink::Send`.
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/// Also `Chunks` need to take `Vec` by value, so we need
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/// to allocate it for each chunk being sent.
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pub struct Reader<R: io::Read> {
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buffer: [u8; MAX_CHUNK_SIZE],
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content: io::BufReader<R>,
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sending: sink::Send<Sender>,
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}
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impl<R: io::Read> Reader<R> {
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pub fn pair(content: R, initial: Vec<u8>) -> (Self, hyper::Body) {
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let (tx, rx) = hyper::Body::pair();
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let reader = Reader {
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buffer: [0; MAX_CHUNK_SIZE],
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content: io::BufReader::new(content),
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sending: tx.send(Ok(initial.into())),
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};
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(reader, rx)
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}
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}
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impl<R: io::Read> Future for Reader<R> {
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type Item = ();
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type Error = ();
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fn poll(&mut self) -> futures::Poll<Self::Item, Self::Error> {
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loop {
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let next = try_ready!(self.sending.poll().map_err(|err| {
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warn!(target: "dapps", "Unable to send next chunk: {:?}", err);
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}));
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self.sending = match self.content.read(&mut self.buffer) {
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Ok(0) => return Ok(futures::Async::Ready(())),
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Ok(read) => next.send(Ok(self.buffer[..read].to_vec().into())),
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Err(err) => next.send(Err(hyper::Error::Io(err))),
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}
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}
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}
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}
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