nephele 0.0.2

A high performance asynchronous programming runtime for Rust.
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

use bytes::{Buf, BufMut, BytesMut};
use std::{cmp, fmt, io, str, usize};

use crate::common::codec::decoder::Decoder;
use crate::common::codec::encoder::Encoder;

#[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct LinesCodec {
    next_index: usize,

    max_length: usize,

    is_discarding: bool,
}

impl LinesCodec {
    pub fn new() -> LinesCodec {
        LinesCodec {
            next_index: 0,
            max_length: usize::MAX,
            is_discarding: false,
        }
    }

    pub fn new_with_max_length(max_length: usize) -> Self {
        LinesCodec {
            max_length,
            ..LinesCodec::new()
        }
    }

    pub fn max_length(&self) -> usize {
        self.max_length
    }
}

fn utf8(buf: &[u8]) -> Result<&str, io::Error> {
    str::from_utf8(buf)
        .map_err(|_| io::Error::new(io::ErrorKind::InvalidData, "Unable to decode input as UTF8"))
}

fn without_carriage_return(s: &[u8]) -> &[u8] {
    if let Some(&b'\r') = s.last() {
        &s[..s.len() - 1]
    } else {
        s
    }
}

impl Decoder for LinesCodec {
    type Item = String;
    type Error = LinesCodecError;

    fn decode(&mut self, buf: &mut BytesMut) -> Result<Option<String>, LinesCodecError> {
        loop {
            let read_to = cmp::min(self.max_length.saturating_add(1), buf.len());

            let newline_offset = buf[self.next_index..read_to]
                .iter()
                .position(|b| *b == b'\n');

            match (self.is_discarding, newline_offset) {
                (true, Some(offset)) => {
                    buf.advance(offset + self.next_index + 1);
                    self.is_discarding = false;
                    self.next_index = 0;
                }
                (true, None) => {
                    buf.advance(read_to);
                    self.next_index = 0;
                    if buf.is_empty() {
                        return Err(LinesCodecError::MaxLineLengthExceeded);
                    }
                }
                (false, Some(offset)) => {
                    let newline_index = offset + self.next_index;
                    self.next_index = 0;
                    let line = buf.split_to(newline_index + 1);
                    let line = &line[..line.len() - 1];
                    let line = without_carriage_return(line);
                    let line = utf8(line)?;
                    return Ok(Some(line.to_string()));
                }
                (false, None) if buf.len() > self.max_length => {
                    self.is_discarding = true;
                    return Err(LinesCodecError::MaxLineLengthExceeded);
                }
                (false, None) => {
                    self.next_index = read_to;
                    return Ok(None);
                }
            }
        }
    }

    fn decode_eof(&mut self, buf: &mut BytesMut) -> Result<Option<String>, LinesCodecError> {
        Ok(match self.decode(buf)? {
            Some(frame) => Some(frame),
            None => {
                if buf.is_empty() || buf == &b"\r"[..] {
                    None
                } else {
                    let line = buf.split_to(buf.len());
                    let line = without_carriage_return(&line);
                    let line = utf8(line)?;
                    self.next_index = 0;
                    Some(line.to_string())
                }
            }
        })
    }
}

impl<T> Encoder<T> for LinesCodec
where
    T: AsRef<str>,
{
    type Error = LinesCodecError;

    fn encode(&mut self, line: T, buf: &mut BytesMut) -> Result<(), LinesCodecError> {
        let line = line.as_ref();
        buf.reserve(line.len() + 1);
        buf.put(line.as_bytes());
        buf.put_u8(b'\n');
        Ok(())
    }
}

impl Default for LinesCodec {
    fn default() -> Self {
        Self::new()
    }
}

#[derive(Debug)]
pub enum LinesCodecError {
    MaxLineLengthExceeded,
    Io(io::Error),
}

impl fmt::Display for LinesCodecError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            LinesCodecError::MaxLineLengthExceeded => write!(f, "max line length exceeded"),
            LinesCodecError::Io(e) => write!(f, "{}", e),
        }
    }
}

impl From<io::Error> for LinesCodecError {
    fn from(e: io::Error) -> LinesCodecError {
        LinesCodecError::Io(e)
    }
}

impl std::error::Error for LinesCodecError {}