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
|
use std::io;
use std::sync::mpsc::TryRecvError;
use futures::{Future, Poll, Async};
use futures::stream::Stream;
use mio::channel;
use {ReadinessStream, LoopHandle};
use io::IoFuture;
/// The transmission half of a channel used for sending messages to a receiver.
///
/// A `Sender` can be `clone`d to have multiple threads or instances sending
/// messages to one receiver.
///
/// This type is created by the `LoopHandle::channel` method.
pub struct Sender<T> {
tx: channel::Sender<T>,
}
/// The receiving half of a channel used for processing messages sent by a
/// `Sender`.
///
/// A `Receiver` cannot be cloned, so only one thread can receive messages at a
/// time.
///
/// This type is created by the `LoopHandle::channel` method and implements the
/// `Stream` trait to represent received messages.
pub struct Receiver<T> {
rx: ReadinessStream<channel::Receiver<T>>,
}
impl LoopHandle {
/// Creates a new in-memory channel used for sending data across `Send +
/// 'static` boundaries, frequently threads.
///
/// This type can be used to conveniently send messages between futures.
/// Unlike the futures crate `channel` method and types, the returned tx/rx
/// pair is a multi-producer single-consumer (mpsc) channel *with no
/// backpressure*. Currently it's left up to the application to implement a
/// mechanism, if necessary, to avoid messages piling up.
///
/// The returned `Sender` can be used to send messages that are processed by
/// the returned `Receiver`. The `Sender` can be cloned to send messages
/// from multiple sources simultaneously.
pub fn channel<T>(self) -> (Sender<T>, IoFuture<Receiver<T>>)
where T: Send + 'static,
{
let (tx, rx) = channel::channel();
let rx = ReadinessStream::new(self, rx).map(|rx| Receiver { rx: rx });
(Sender { tx: tx }, rx.boxed())
}
}
impl<T> Sender<T> {
/// Sends a message to the corresponding receiver of this sender.
///
/// The message provided will be enqueued on the channel immediately, and
/// this function will return immediately. Keep in mind that the
/// underlying channel has infinite capacity, and this may not always be
/// desired.
///
/// If an I/O error happens while sending the message, or if the receiver
/// has gone away, then an error will be returned. Note that I/O errors here
/// are generally quite abnormal.
pub fn send(&self, t: T) -> io::Result<()> {
self.tx.send(t).map_err(|e| {
match e {
channel::SendError::Io(e) => e,
channel::SendError::Disconnected(_) => {
io::Error::new(io::ErrorKind::Other,
"channel has been disconnected")
}
}
})
}
}
impl<T> Clone for Sender<T> {
fn clone(&self) -> Sender<T> {
Sender { tx: self.tx.clone() }
}
}
impl<T> Stream for Receiver<T> {
type Item = T;
type Error = io::Error;
fn poll(&mut self) -> Poll<Option<T>, io::Error> {
try_ready!(self.rx.poll_read());
match self.rx.get_ref().try_recv() {
Ok(t) => Ok(Async::Ready(Some(t))),
Err(TryRecvError::Empty) => {
self.rx.need_read();
Ok(Async::NotReady)
}
Err(TryRecvError::Disconnected) => Ok(Async::Ready(None)),
}
}
}
|
