    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
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183

    use std::{
        collections::VecDeque,
        future::poll_fn,
        io,
        pin::Pin,
        task::{Context, Poll},
    };

    use actix_codec::{Decoder, Encoder};
    use actix_http::{
        ws::{Codec, Frame, Message, ProtocolError},
        Payload,
    };
    use actix_web::{
        web::{Bytes, BytesMut},
        Error,
    };
    use futures_core::stream::Stream;
    use tokio::sync::mpsc::Receiver;

    /// A response body for Websocket HTTP Requests
    pub struct StreamingBody {
        session_rx: Receiver<Message>,

        messages: VecDeque<Message>,
        buf: BytesMut,
        codec: Codec,
        closing: bool,
    }

    /// A stream of Messages from a websocket client
    ///
    /// Messages can be accessed via the stream's `.next()` method
    pub struct MessageStream {
        payload: Payload,

        messages: VecDeque<Message>,
        buf: BytesMut,
        codec: Codec,
        closing: bool,
    }

    impl StreamingBody {
        pub(super) fn new(session_rx: Receiver<Message>) -> Self {
            StreamingBody {
                session_rx,
                messages: VecDeque::new(),
                buf: BytesMut::new(),
                codec: Codec::new(),
                closing: false,
            }
        }
    }

    impl MessageStream {
        pub(super) fn new(payload: Payload) -> Self {
            MessageStream {
                payload,
                messages: VecDeque::new(),
                buf: BytesMut::new(),
                codec: Codec::new(),
                closing: false,
            }
        }

        /// Wait for the next item from the message stream
        ///
        /// ```rust,ignore
        /// while let Some(Ok(msg)) = stream.recv().await {
        ///     // handle message
        /// }
        /// ```
        pub async fn recv(&mut self) -> Option<Result<Message, ProtocolError>> {
            poll_fn(|cx| Pin::new(&mut *self).poll_next(cx)).await
        }
    }

    impl Stream for StreamingBody {
        type Item = Result<Bytes, Error>;

        fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
            let this = self.get_mut();

            if this.closing {
                return Poll::Ready(None);
            }

            loop {
                match Pin::new(&mut this.session_rx).poll_recv(cx) {
                    Poll::Ready(Some(msg)) => {
                        this.messages.push_back(msg);
                    }
                    Poll::Ready(None) => {
                        this.closing = true;
                        break;
                    }
                    Poll::Pending => break,
                }
            }

            while let Some(msg) = this.messages.pop_front() {
                if let Err(e) = this.codec.encode(msg, &mut this.buf) {
                    return Poll::Ready(Some(Err(e.into())));
                }
            }

            if !this.buf.is_empty() {
                return Poll::Ready(Some(Ok(this.buf.split().freeze())));
            }

            Poll::Pending
        }
    }

    impl Stream for MessageStream {
        type Item = Result<Message, ProtocolError>;

        fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
            let this = self.get_mut();

            // Return the first message in the queue if one exists
            //
            // This is faster than polling and parsing
            if let Some(msg) = this.messages.pop_front() {
                return Poll::Ready(Some(Ok(msg)));
            }

            if !this.closing {
                // Read in bytes until there's nothing left to read
                loop {
                    match Pin::new(&mut this.payload).poll_next(cx) {
                        Poll::Ready(Some(Ok(bytes))) => {
                            this.buf.extend_from_slice(&bytes);
                        }
                        Poll::Ready(Some(Err(e))) => {
                            return Poll::Ready(Some(Err(ProtocolError::Io(io::Error::new(
                                io::ErrorKind::Other,
                                e.to_string(),
                            )))));
                        }
                        Poll::Ready(None) => {
                            this.closing = true;
                            break;
                        }
                        Poll::Pending => break,
                    }
                }
            }

            // Create messages until there's no more bytes left
            while let Some(frame) = this.codec.decode(&mut this.buf)? {
                let message = match frame {
                    Frame::Text(bytes) => {
                        let s = std::str::from_utf8(&bytes)
                            .map_err(|e| {
                                ProtocolError::Io(io::Error::new(io::ErrorKind::Other, e.to_string()))
                            })?
                            .to_string();
                        Message::Text(s.into())
                    }
                    Frame::Binary(bytes) => Message::Binary(bytes),
                    Frame::Ping(bytes) => Message::Ping(bytes),
                    Frame::Pong(bytes) => Message::Pong(bytes),
                    Frame::Close(reason) => Message::Close(reason),
                    Frame::Continuation(item) => Message::Continuation(item),
                };

                this.messages.push_back(message);
            }

            // Return the first message in the queue
            if let Some(msg) = this.messages.pop_front() {
                return Poll::Ready(Some(Ok(msg)));
            }

            // If we've exhausted our message queue and we're closing, close the stream
            if this.closing {
                return Poll::Ready(None);
            }

            Poll::Pending
        }
    }