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
use std::sync::mpsc::{channel, Sender, Receiver, RecvError};
#[derive(Debug)]
pub struct Funnel<T> {
sources: Vec<Receiver<T>>,
next_index: usize
}
impl<T> Funnel<T> {
pub fn new() -> Funnel<T> {
Funnel {
sources: Vec::new(),
next_index: 0
}
}
pub fn push(&mut self, receiver: Receiver<T>) {
self.sources.push(receiver);
}
pub fn len(&self) -> usize {
self.sources.len()
}
pub fn remove(&mut self, index: usize) -> Receiver<T> {
self.sources.remove(index)
}
pub fn add_receiver(&mut self) -> Sender<T> {
let (tx, rx) = channel();
self.push(rx);
tx
}
pub fn recv(&mut self) -> (Option<T>, Vec<(RecvError, usize)>) {
let mut errors: Vec<(RecvError, usize)> = Vec::new();
let mut index: usize = self.next_index;
loop {
match self.sources[index].recv() {
Err(e) => errors.push((e, index)),
Ok(value) => {
self.next_index = index + 1 % self.sources.len();
return (Some(value), errors);
},
};
index = (index + 1) % self.sources.len();
if index == self.next_index - 1 {
break;
}
}
(None, errors)
}
}
#[cfg(test)]
mod tests {
use super::Funnel;
use std::sync::mpsc::channel;
#[test]
fn single_read() {
let mut funnel = Funnel::new();
let (tx, rx) = channel();
funnel.push(rx);
let _ = tx.send(1).unwrap();
let (received, errors) = funnel.recv();
assert!(received.is_some());
assert!(match received {
Some(value) => value == 1,
_ => false,
});
assert_eq!(errors.len(), 0);
}
#[test]
fn multiple_read() {
let mut funnel: Funnel<i32> = Funnel::new();
let writer1 = funnel.add_receiver();
let writer2 = funnel.add_receiver();
let _ = writer1.send(1).unwrap();
let _ = writer2.send(2).unwrap();
let (received, errors) = funnel.recv();
assert!(received.is_some());
println!("{:?}", received);
assert!(match received {
Some(value) => value == 1,
_ => false,
});
assert_eq!(errors.len(), 0);
let (received, errors) = funnel.recv();
assert!(received.is_some());
println!("{:?}", errors);
assert!(match received {
Some(value) => value == 2,
_ => false,
});
assert_eq!(errors.len(), 0);
}
}