1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165

use std::fmt;
use std::io;

use bytes::Bytes;
use futures::{future, stream, Async, Future, Poll, Stream};
use tokio::io::AsyncRead;

/// Stream of bytes.
pub struct ByteStream {
    size_hint: Option<usize>,
    inner: Box<dyn Stream<Item = Bytes, Error = io::Error> + Send>,
}

impl ByteStream {
    /// Create a new `ByteStream` by wrapping a `futures` stream.
    pub fn new<S>(stream: S) -> ByteStream
    where
        S: Stream<Item = Bytes, Error = io::Error> + Send + 'static,
    {
        ByteStream {
            size_hint: None,
            inner: Box::new(stream),
        }
    }

    pub(crate) fn size_hint(&self) -> Option<usize> {
        self.size_hint
    }

    /// Return an implementation of `AsyncRead` that uses async i/o to consume the stream.
    pub fn into_async_read(self) -> impl AsyncRead + Send {
        ImplAsyncRead::new(self.inner)
    }

    /// Return an implementation of `Read` that uses blocking i/o to consume the stream.
    pub fn into_blocking_read(self) -> impl io::Read + Send {
        ImplBlockingRead::new(self.inner)
    }
}

impl From<Vec<u8>> for ByteStream {
    fn from(buf: Vec<u8>) -> ByteStream {
        ByteStream {
            size_hint: Some(buf.len()),
            inner: Box::new(stream::once(Ok(Bytes::from(buf)))),
        }
    }
}

impl fmt::Debug for ByteStream {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "<ByteStream size_hint={:?}>", self.size_hint)
    }
}

impl Stream for ByteStream {
    type Item = Bytes;
    type Error = io::Error;

    fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
        self.inner.poll()
    }
}

struct ImplAsyncRead {
    buffer: io::Cursor<Bytes>,
    stream: stream::Fuse<Box<dyn Stream<Item = Bytes, Error = io::Error> + Send>>,
}

impl ImplAsyncRead {
    fn new(stream: Box<dyn Stream<Item = Bytes, Error = io::Error> + Send>) -> Self {
        ImplAsyncRead {
            buffer: io::Cursor::new(Bytes::new()),
            stream: stream.fuse(),
        }
    }
}

impl io::Read for ImplAsyncRead {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        if buf.is_empty() {
            return Ok(0);
        }
        loop {
            let n = self.buffer.read(buf)?;
            if n > 0 {
                return Ok(n);
            }
            match self.stream.poll()? {
                Async::NotReady => {
                    return Err(io::ErrorKind::WouldBlock.into());
                }
                Async::Ready(Some(buffer)) => {
                    self.buffer = io::Cursor::new(buffer);
                    continue;
                }
                Async::Ready(None) => {
                    return Ok(0);
                }
            }
        }
    }
}

impl AsyncRead for ImplAsyncRead {}

struct ImplBlockingRead {
    inner: ImplAsyncRead,
}

impl ImplBlockingRead {
    fn new(stream: Box<dyn Stream<Item = Bytes, Error = io::Error> + Send>) -> Self {
        ImplBlockingRead {
            inner: ImplAsyncRead::new(stream),
        }
    }
}

impl io::Read for ImplBlockingRead {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        future::poll_fn(|| self.inner.poll_read(buf)).wait()
    }
}

#[test]
fn test_async_read() {
    use bytes::Bytes;
    use std::io::Read;

    let chunks = vec![Bytes::from_static(b"1234"), Bytes::from_static(b"5678")];
    let stream = ByteStream::new(stream::iter_ok(chunks));
    let mut async_read = stream.into_async_read();

    let mut buf = [0u8; 3];
    assert_eq!(async_read.read(&mut buf).unwrap(), 3);
    assert_eq!(&buf[..3], b"123");
    assert_eq!(async_read.read(&mut buf).unwrap(), 1);
    assert_eq!(&buf[..1], b"4");
    assert_eq!(async_read.read(&mut buf).unwrap(), 3);
    assert_eq!(&buf[..3], b"567");
    assert_eq!(async_read.read(&mut buf).unwrap(), 1);
    assert_eq!(&buf[..1], b"8");
    assert_eq!(async_read.read(&mut buf).unwrap(), 0);
}

#[test]
fn test_blocking_read() {
    use bytes::Bytes;
    use std::io::Read;

    let chunks = vec![Bytes::from_static(b"1234"), Bytes::from_static(b"5678")];
    let stream = ByteStream::new(stream::iter_ok(chunks));
    let mut async_read = stream.into_blocking_read();

    let mut buf = [0u8; 3];
    assert_eq!(async_read.read(&mut buf).unwrap(), 3);
    assert_eq!(&buf[..3], b"123");
    assert_eq!(async_read.read(&mut buf).unwrap(), 1);
    assert_eq!(&buf[..1], b"4");
    assert_eq!(async_read.read(&mut buf).unwrap(), 3);
    assert_eq!(&buf[..3], b"567");
    assert_eq!(async_read.read(&mut buf).unwrap(), 1);
    assert_eq!(&buf[..1], b"8");
    assert_eq!(async_read.read(&mut buf).unwrap(), 0);
}