Initial commit

.github/workflows/ci.yml

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+name: Continuous integration
+
+on:
+  pull_request:
+  push:
+    branches:    
+      - master
+
+jobs:
+  test:
+    name: Build and test
+    runs-on: ubuntu-latest
+    container:
+      image: rust
+    steps:
+    - uses: actions/checkout@v1
+    - name: Run tests
+      run: cargo test

.gitignore

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+Cargo.lock
+target

Cargo.toml

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+[package]
+name = "rw-stream-sink"
+edition = "2018"
+description = "Adaptator between Stream/Sink and AsyncRead/AsyncWrite"
+version = "0.2.1"
+authors = ["Parity Technologies <admin@parity.io>"]
+license = "MIT"
+repository = "https://github.com/paritytech/rw-stream-sink"
+keywords = ["networking"]
+categories = ["network-programming", "asynchronous"]
+
+[dependencies]
+futures = "0.3.1"
+pin-project = "0.4.6"
+static_assertions = "1"
+
+[dev-dependencies]
+async-std = "1.0"

LICENSE

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+Copyright 2017-2020 Parity Technologies (UK) Ltd.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
+OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+This crate provides the `RwStreamSink` type. It wraps around a `Stream`
+and `Sink` that produces and accepts byte arrays, and implements the
+`AsyncRead` and `AsyncWrite` traits.
+
+Each call to `AsyncWrite::poll_write` will send one packet to the sink.
+Calls to `AsyncRead::poll_read` will read from the stream's incoming packets.

src/lib.rs

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+// Copyright 2017-2020 Parity Technologies (UK) Ltd.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+//! This crate provides the [`RwStreamSink`] type. It wraps around a [`Stream`]
+//! and [`Sink`] that produces and accepts byte arrays, and implements
+//! [`AsyncRead`] and [`AsyncWrite`].
+//!
+//! Each call to [`AsyncWrite::poll_write`] will send one packet to the sink.
+//! Calls to [`AsyncRead::poll_read`] will read from the stream's incoming packets.
+
+use futures::{prelude::*, ready};
+use std::{
+    io::{self, Read},
+    mem,
+    pin::Pin,
+    task::{Context, Poll},
+};
+
+static_assertions::const_assert!(mem::size_of::<usize>() <= mem::size_of::<u64>());
+
+/// Wraps a [`Stream`] and [`Sink`] whose items are buffers.
+/// Implements [`AsyncRead`] and [`AsyncWrite`].
+#[pin_project::pin_project]
+pub struct RwStreamSink<S: TryStream> {
+    #[pin]
+    inner: S,
+    current_item: Option<std::io::Cursor<<S as TryStream>::Ok>>,
+}
+
+impl<S: TryStream> RwStreamSink<S> {
+    /// Wraps around `inner`.
+    pub fn new(inner: S) -> Self {
+        RwStreamSink {
+            inner,
+            current_item: None,
+        }
+    }
+}
+
+impl<S> AsyncRead for RwStreamSink<S>
+where
+    S: TryStream<Error = io::Error>,
+    <S as TryStream>::Ok: AsRef<[u8]>,
+{
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context,
+        buf: &mut [u8],
+    ) -> Poll<io::Result<usize>> {
+        let mut this = self.project();
+
+        // Grab the item to copy from.
+        let item_to_copy = loop {
+            if let Some(ref mut i) = this.current_item {
+                if i.position() < i.get_ref().as_ref().len() as u64 {
+                    break i;
+                }
+            }
+            *this.current_item = Some(match ready!(this.inner.as_mut().try_poll_next(cx)) {
+                Some(Ok(i)) => std::io::Cursor::new(i),
+                Some(Err(e)) => return Poll::Ready(Err(e)),
+                None => return Poll::Ready(Ok(0)), // EOF
+            });
+        };
+
+        // Copy it!
+        Poll::Ready(Ok(item_to_copy.read(buf)?))
+    }
+}
+
+impl<S> AsyncWrite for RwStreamSink<S>
+where
+    S: TryStream + Sink<<S as TryStream>::Ok, Error = io::Error>,
+    <S as TryStream>::Ok: for<'r> From<&'r [u8]>,
+{
+    fn poll_write(self: Pin<&mut Self>, cx: &mut Context, buf: &[u8]) -> Poll<io::Result<usize>> {
+        let mut this = self.project();
+        ready!(this.inner.as_mut().poll_ready(cx)?);
+        let n = buf.len();
+        if let Err(e) = this.inner.start_send(buf.into()) {
+            return Poll::Ready(Err(e));
+        }
+        Poll::Ready(Ok(n))
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context) -> Poll<io::Result<()>> {
+        let this = self.project();
+        this.inner.poll_flush(cx)
+    }
+
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context) -> Poll<io::Result<()>> {
+        let this = self.project();
+        this.inner.poll_close(cx)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::RwStreamSink;
+    use async_std::task;
+    use futures::{channel::mpsc, prelude::*, stream};
+    use std::{
+        pin::Pin,
+        task::{Context, Poll},
+    };
+
+    // This struct merges a stream and a sink and is quite useful for tests.
+    struct Wrapper<St, Si>(St, Si);
+
+    impl<St, Si> Stream for Wrapper<St, Si>
+    where
+        St: Stream + Unpin,
+        Si: Unpin,
+    {
+        type Item = St::Item;
+
+        fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
+            self.0.poll_next_unpin(cx)
+        }
+    }
+
+    impl<St, Si, T> Sink<T> for Wrapper<St, Si>
+    where
+        St: Unpin,
+        Si: Sink<T> + Unpin,
+    {
+        type Error = Si::Error;
+
+        fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+            Pin::new(&mut self.1).poll_ready(cx)
+        }
+
+        fn start_send(mut self: Pin<&mut Self>, item: T) -> Result<(), Self::Error> {
+            Pin::new(&mut self.1).start_send(item)
+        }
+
+        fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+            Pin::new(&mut self.1).poll_flush(cx)
+        }
+
+        fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
+            Pin::new(&mut self.1).poll_close(cx)
+        }
+    }
+
+    #[test]
+    fn basic_reading() {
+        let (tx1, _) = mpsc::channel::<Vec<u8>>(10);
+        let (mut tx2, rx2) = mpsc::channel(10);
+
+        let mut wrapper = RwStreamSink::new(Wrapper(rx2.map(Ok), tx1));
+
+        task::block_on(async move {
+            tx2.send(Vec::from("hel")).await.unwrap();
+            tx2.send(Vec::from("lo wor")).await.unwrap();
+            tx2.send(Vec::from("ld")).await.unwrap();
+            tx2.close().await.unwrap();
+
+            let mut data = Vec::new();
+            wrapper.read_to_end(&mut data).await.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(data).map(Ok));
+        let mut buf = [0; 9];
+        task::block_on(async move {
+            assert_eq!(3, rws.read(&mut buf).await.unwrap());
+            assert_eq!(3, rws.read(&mut buf[3..]).await.unwrap());
+            assert_eq!(3, rws.read(&mut buf[6..]).await.unwrap());
+            assert_eq!(0, rws.read(&mut buf).await.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(data).map(Ok));
+        let mut buf = [0; 3];
+        task::block_on(async move {
+            assert_eq!(3, rws.read(&mut buf).await.unwrap());
+            assert_eq!(b"hel", &buf[..3]);
+            assert_eq!(0, rws.read(&mut buf[..0]).await.unwrap());
+            assert_eq!(1, rws.read(&mut buf).await.unwrap());
+            assert_eq!(b"l", &buf[..1]);
+            assert_eq!(3, rws.read(&mut buf).await.unwrap());
+            assert_eq!(b"o w", &buf[..3]);
+            assert_eq!(0, rws.read(&mut buf[..0]).await.unwrap());
+            assert_eq!(3, rws.read(&mut buf).await.unwrap());
+            assert_eq!(b"orl", &buf[..3]);
+            assert_eq!(1, rws.read(&mut buf).await.unwrap());
+            assert_eq!(b"d", &buf[..1]);
+            assert_eq!(0, rws.read(&mut buf).await.unwrap());
+        })
+    }
+}