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

use std::marker::PhantomData;

use bincode::Options as _;
use futures::channel::mpsc::{Receiver, Sender};
use serde::{Deserialize, Serialize};
use thiserror::Error;

use crate::{
    packet::PacketPool,
    unreliable_channel::{self, UnreliableChannel, MAX_MESSAGE_LEN},
};

#[derive(Debug, Error)]
pub enum SendError {
    #[error("outgoing packet stream has been disconnected")]
    Disconnected,
    #[error("bincode serialization error: {0}")]
    BincodeError(bincode::Error),
}

#[derive(Debug, Error)]
pub enum RecvError {
    #[error("incoming packet stream has been disconnected")]
    Disconnected,
    #[error("incoming packet has bad message format")]
    BadFormat,
    #[error("bincode serialization error: {0}")]
    BincodeError(bincode::Error),
}

/// Wraps an `UnreliableChannel` together with an internal buffer to allow easily sending message
/// types serialized with `bincode`.
///
/// Just like the underlying channel, messages are not guaranteed to arrive, nor are they guaranteed
/// to arrive in order.
pub struct UnreliableBincodeChannel<P>
where
    P: PacketPool,
{
    channel: UnreliableChannel<P>,
    buffer: Box<[u8]>,
}

impl<P> UnreliableBincodeChannel<P>
where
    P: PacketPool,
{
    pub fn new(packet_pool: P, incoming: Receiver<P::Packet>, outgoing: Sender<P::Packet>) -> Self {
        UnreliableBincodeChannel {
            channel: UnreliableChannel::new(packet_pool, incoming, outgoing),
            buffer: vec![0; MAX_MESSAGE_LEN].into_boxed_slice(),
        }
    }

    /// Write the given serializable message type to the channel.
    ///
    /// Messages are coalesced into larger packets before being sent, so in order to guarantee that
    /// the message is actually sent, you must call `flush`.
    pub async fn send<T: Serialize>(&mut self, msg: &T) -> Result<(), SendError> {
        let mut w = &mut self.buffer[..];
        bincode_config()
            .serialize_into(&mut w, msg)
            .map_err(SendError::BincodeError)?;
        let remaining = w.len();
        let written = self.buffer.len() - remaining;
        self.channel
            .send(&self.buffer[0..written])
            .await
            .map_err(from_inner_send_err)
    }

    /// Finish sending any unsent coalesced packets.
    ///
    /// This *must* be called to guarantee that any sent messages are actually sent to the outgoing
    /// packet stream.
    pub async fn flush(&mut self) -> Result<(), SendError> {
        self.channel.flush().await.map_err(from_inner_send_err)
    }

    /// Receive a deserializable message type as soon as the next message is available.
    pub async fn recv<'a, T: Deserialize<'a>>(&'a mut self) -> Result<T, RecvError> {
        let len = self
            .channel
            .recv(&mut self.buffer[..])
            .await
            .map_err(from_inner_recv_err)?;
        bincode_config()
            .deserialize(&self.buffer[0..len])
            .map_err(RecvError::BincodeError)
    }
}

/// Wrapper over an `UnreliableBincodeChannel` that only allows a single message type.
pub struct UnreliableTypedChannel<T, P>
where
    P: PacketPool,
{
    channel: UnreliableBincodeChannel<P>,
    _phantom: PhantomData<T>,
}

impl<T, P> UnreliableTypedChannel<T, P>
where
    P: PacketPool,
{
    pub fn new(packet_pool: P, incoming: Receiver<P::Packet>, outgoing: Sender<P::Packet>) -> Self {
        UnreliableTypedChannel {
            channel: UnreliableBincodeChannel::new(packet_pool, incoming, outgoing),
            _phantom: PhantomData,
        }
    }

    pub async fn flush(&mut self) -> Result<(), SendError> {
        self.channel.flush().await
    }
}

impl<T, P> UnreliableTypedChannel<T, P>
where
    T: Serialize,
    P: PacketPool,
{
    pub async fn send(&mut self, msg: &T) -> Result<(), SendError> {
        self.channel.send(msg).await
    }
}

impl<'a, T, P> UnreliableTypedChannel<T, P>
where
    T: Deserialize<'a>,
    P: PacketPool,
{
    pub async fn recv(&'a mut self) -> Result<T, RecvError> {
        self.channel.recv().await
    }
}

fn from_inner_send_err(err: unreliable_channel::SendError) -> SendError {
    match err {
        unreliable_channel::SendError::Disconnected => SendError::Disconnected,
        unreliable_channel::SendError::TooBig => {
            unreachable!("messages that are too large are caught by bincode configuration")
        }
    }
}

fn from_inner_recv_err(err: unreliable_channel::RecvError) -> RecvError {
    match err {
        unreliable_channel::RecvError::Disconnected => RecvError::Disconnected,
        unreliable_channel::RecvError::BadFormat => RecvError::BadFormat,
        unreliable_channel::RecvError::TooBig => {
            unreachable!("messages that are too large are caught by bincode configuration")
        }
    }
}

fn bincode_config() -> impl bincode::Options + Copy {
    bincode::options().with_limit(MAX_MESSAGE_LEN as u64)
}