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
use BindServer;
use futures::stream::Stream;
use futures::{Future, IntoFuture, Poll, Async};
use std::collections::VecDeque;
use std::io;
use streaming::{Message, Body};
use super::advanced::{Pipeline, PipelineMessage};
use super::{Frame, Transport};
use tokio_core::reactor::Handle;
use tokio_service::Service;

// TODO:
//
// - Wait for service readiness
// - Handle request body stream cancellation

/// A streaming, pipelined server protocol.
///
/// The `T` parameter is used for the I/O object used to communicate, which is
/// supplied in `bind_transport`.
///
/// For simple protocols, the `Self` type is often a unit struct. In more
/// advanced cases, `Self` may contain configuration information that is used
/// for setting up the transport in `bind_transport`.
pub trait ServerProto<T: 'static>: 'static {
    /// Request headers.
    type Request: 'static;

    /// Request body chunks.
    type RequestBody: 'static;

    /// Response headers.
    type Response: 'static;

    /// Response body chunks.
    type ResponseBody: 'static;

    /// Errors, which are used both for error frames and for the service itself.
    type Error: From<io::Error> + 'static;

    /// The frame transport, which usually take `T` as a parameter.
    type Transport:
        Transport<Item = Frame<Self::Request, Self::RequestBody, Self::Error>,
                  SinkItem = Frame<Self::Response, Self::ResponseBody, Self::Error>>;

    /// A future for initializing a transport from an I/O object.
    ///
    /// In simple cases, `Result<Self::Transport, Self::Error>` often suffices.
    type BindTransport: IntoFuture<Item = Self::Transport, Error = io::Error>;

    /// Build a transport from the given I/O object, using `self` for any
    /// configuration.
    fn bind_transport(&self, io: T) -> Self::BindTransport;
}

impl<P, T, B> BindServer<super::StreamingPipeline<B>, T> for P where
    P: ServerProto<T>,
    T: 'static,
    B: Stream<Item = P::ResponseBody, Error = P::Error>,
{
    type ServiceRequest = Message<P::Request, Body<P::RequestBody, P::Error>>;
    type ServiceResponse = Message<P::Response, B>;
    type ServiceError = P::Error;

    fn bind_server<S>(&self, handle: &Handle, io: T, service: S)
        where S: Service<Request = Self::ServiceRequest,
                         Response = Self::ServiceResponse,
                         Error = Self::ServiceError> + 'static
    {
        let task = self.bind_transport(io).into_future().and_then(|transport| {
            let dispatch: Dispatch<S, T, P> = Dispatch {
                service: service,
                transport: transport,
                in_flight: VecDeque::with_capacity(32),
            };
            Pipeline::new(dispatch)
        });

        // Spawn the pipeline dispatcher
        handle.spawn(task.map_err(|_| ()))
    }
}

struct Dispatch<S, T, P> where
    T: 'static, P: ServerProto<T>, S: Service
{
    // The service handling the connection
    service: S,
    transport: P::Transport,
    in_flight: VecDeque<InFlight<S::Future>>,
}

enum InFlight<F: Future> {
    Active(F),
    Done(Result<F::Item, F::Error>),
}

impl<P, T, B, S> super::advanced::Dispatch for Dispatch<S, T, P> where
    P: ServerProto<T>,
    T: 'static,
    B: Stream<Item = P::ResponseBody, Error = P::Error>,
    S: Service<Request = Message<P::Request, Body<P::RequestBody, P::Error>>,
               Response = Message<P::Response, B>,
               Error = P::Error>,
{
    type Io = T;
    type In = P::Response;
    type BodyIn = P::ResponseBody;
    type Out = P::Request;
    type BodyOut = P::RequestBody;
    type Error = P::Error;
    type Stream = B;
    type Transport = P::Transport;

    fn transport(&mut self) -> &mut P::Transport {
        &mut self.transport
    }

    fn dispatch(&mut self,
                request: PipelineMessage<Self::Out, Body<Self::BodyOut, Self::Error>, Self::Error>)
                -> io::Result<()>
    {
        if let Ok(request) = request {
            let response = self.service.call(request);
            self.in_flight.push_back(InFlight::Active(response));
        }

        // TODO: Should the error be handled differently?

        Ok(())
    }

    fn poll(&mut self) -> Poll<Option<PipelineMessage<Self::In, Self::Stream, Self::Error>>, io::Error> {
        for slot in self.in_flight.iter_mut() {
            slot.poll();
        }

        match self.in_flight.front() {
            Some(&InFlight::Done(_)) => {}
            _ => return Ok(Async::NotReady)
        }

        match self.in_flight.pop_front() {
            Some(InFlight::Done(res)) => Ok(Async::Ready(Some(res))),
            _ => panic!(),
        }
    }

    fn has_in_flight(&self) -> bool {
        !self.in_flight.is_empty()
    }
}

impl<F: Future> InFlight<F> {
    fn poll(&mut self) {
        let res = match *self {
            InFlight::Active(ref mut f) => {
                match f.poll() {
                    Ok(Async::Ready(e)) => Ok(e),
                    Err(e) => Err(e),
                    Ok(Async::NotReady) => return,
                }
            }
            _ => return,
        };
        *self = InFlight::Done(res);
    }
}