noxious 1.0.4

The core library for noxious, a Rust port of Toxiproxy
Documentation 
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

use bytes::Bytes;
use futures::{Sink, Stream};
use futures::{SinkExt, StreamExt};
use rand::{rngs::StdRng, Rng, SeedableRng};
use std::convert::TryInto;
use std::io;
use tokio::pin;
use tokio::time::sleep;
use tokio::time::Duration;

/// Run the slicer toxic
pub async fn run_slicer(
    input: impl Stream<Item = Bytes>,
    output: impl Sink<Bytes>,
    average_size: u64,
    size_variation: u64,
    delay: u64, // microseconds
    rand_seed: Option<u64>,
) -> io::Result<()> {
    pin!(input);
    pin!(output);

    while let Some(chunk) = input.next().await {
        let slice_iter = SliceIter::new(chunk, average_size, size_variation, rand_seed);
        for slice in slice_iter {
            sleep(Duration::from_micros(delay)).await;
            if output.send(slice).await.is_err() {
                return Err(io::Error::new(
                    io::ErrorKind::ConnectionReset,
                    "Write channel closed",
                ));
            }
        }
    }
    Ok(())
}

#[derive(Debug)]
enum SliceIterKind {
    ConstantSized,
    VariableSized {
        size_variation: usize,
        // Boxed to keep the variant size variation small
        rand_gen: Box<StdRng>,
    },
}

#[derive(Debug)]
struct SliceIter {
    data: Option<Bytes>,
    average_size: usize,
    kind: SliceIterKind,
}

impl SliceIter {
    fn new(
        data: Bytes,
        average_size: u64,
        size_variation: u64,
        rand_seed: Option<u64>,
    ) -> SliceIter {
        let kind = if size_variation > 0 {
            let rand_gen = if let Some(seed) = rand_seed {
                StdRng::seed_from_u64(seed)
            } else {
                StdRng::from_entropy()
            };
            SliceIterKind::VariableSized {
                size_variation: size_variation
                    .try_into()
                    .expect("Could not convert size_variation from u64 to usize"),
                rand_gen: Box::new(rand_gen),
            }
        } else {
            SliceIterKind::ConstantSized
        };
        SliceIter {
            data: Some(data),
            average_size: average_size
                .try_into()
                .expect("Could not convert average_size from u64 to usize"),
            kind,
        }
    }

    fn slice_data(&mut self, position: usize) -> Option<Bytes> {
        if let Some(mut data) = self.data.take() {
            if data.len() > position {
                let slice = data.split_to(position);
                self.data = Some(data);
                Some(slice)
            } else if !data.is_empty() {
                Some(data)
            } else {
                None
            }
        } else {
            None
        }
    }
}

impl Iterator for SliceIter {
    type Item = Bytes;

    fn next(&mut self) -> Option<Self::Item> {
        if self.data.is_some() {
            match &mut self.kind {
                SliceIterKind::ConstantSized => self.slice_data(self.average_size),
                SliceIterKind::VariableSized {
                    size_variation,
                    rand_gen,
                } => {
                    let variation = *size_variation;
                    let size =
                        self.average_size + 2 * rand_gen.gen_range(1..=variation) - variation;
                    self.slice_data(size)
                }
            }
        } else {
            None
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::toxics::test_utils::*;

    #[tokio::test]
    async fn passthrough_once() {
        passthrough_test(
            |stream, sink| async move { run_slicer(stream, sink, 50, 0, 0, None).await },
        )
        .await;
    }

    #[tokio::test]
    async fn random_seed_passthrough_once() {
        passthrough_test(|stream, sink| async move {
            run_slicer(stream, sink, 50, 0, 0, Some(42)).await
        })
        .await;
    }

    #[tokio::test]
    async fn random_seed_variation_passthrough_once() {
        passthrough_test(|stream, sink| async move {
            run_slicer(stream, sink, 50, 8, 0, Some(42)).await
        })
        .await;
    }

    #[tokio::test]
    async fn variation_passthrough_once() {
        passthrough_test(
            |stream, sink| async move { run_slicer(stream, sink, 50, 8, 0, None).await },
        )
        .await;
    }
}