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 collections::vec_deque::VecDeque;
use core::cmp;
use deferred::Deferred;
use io::{AsyncRead,Promise,Write};
use mutex::Mutex;
use prelude::*;
use syscall::Result;

struct IoRequest {
    buf: Vec<u8>,
    d: Deferred<Result<Vec<u8>>>,
    current: usize
}

impl IoRequest {
    pub fn new(buf: Vec<u8>, d: Deferred<Result<Vec<u8>>>) -> Self {
        IoRequest {
            buf: buf,
            d: d,
            current: 0
        }
    }

    pub fn fulfil(mut self, data: &mut VecDeque<u8>) -> Option<Self> {
        {
            let len = cmp::min(self.buf.len(), data.len());
            let right = data.split_off(len);

            for (i, b) in data.iter().enumerate() {
                self.buf[self.current + i] = *b
            }

            self.current += len;
            *data = right
        }

        if self.current >= self.buf.len() {
            self.d.resolve(Ok(self.buf));
            None
        } else {
            Some(self)
        }
    }
}

pub struct Pipe {
    data: Mutex<VecDeque<u8>>,
    requests: Mutex<VecDeque<IoRequest>>
}

impl Pipe {
    pub fn new() -> Self {
        Pipe {
            data: Mutex::new(VecDeque::new()),
            requests: Mutex::new(VecDeque::new())
        }
    }

    pub fn queue_len(&self) -> usize {
        lock!(self.data).len()
    }

    fn fulfil(&self) -> bool {
        let mut data = lock!(self.data);
        loop {
            let mut requests = lock!(self.requests);
            let request: IoRequest =
                match requests.pop_front() {
                    Some(request) => request,
                    None => { return false; }
                };

            if let Some(request) = request.fulfil(&mut data) {
                requests.push_front(request);
            }

            if data.len() == 0 {
                return !requests.is_empty();
            }
        }
    }
}

impl AsyncRead for Pipe {
    fn read_async(&self, buf: Vec<u8>) -> Promise<Result<Vec<u8>>> {
        let d = Deferred::new();
        lock!(self.requests).push_back(IoRequest::new(buf, d.clone()));
        self.fulfil();
        Promise::new(d)
    }
}

impl Write for Pipe {
    fn write(&self, buf: &[u8]) -> Result<usize> {
        lock!(self.data).extend(buf);
        self.fulfil();
        Ok(buf.len())
    }
}

#[cfg(feature = "test")]
pub mod test {
    use io::{AsyncRead,Write};
    use prelude::*;
    use super::*;

    fn test_read(pipe: &Pipe, expected: &[u8]) {
        let buf = vec![0; expected.len()];
        let d = pipe.read_async(buf);
        let buf = d.try_get().unwrap_or_else(|_| panic!("didn't expect to block")).unwrap();
        let mut v = Vec::<u8>::new();
        v.extend(expected);
        assert_eq!(v, buf);
    }

    test! {
        fn can_read_nothing() {
            let pipe = Pipe::new();
            test_read(&pipe, b"");
        }

        fn can_read_chunks() {
            let pipe = Pipe::new();
            pipe.write(b"hello").unwrap();
            test_read(&pipe, b"h");
            test_read(&pipe, b"ell");
            test_read(&pipe, b"o");
            assert_eq!(0, pipe.queue_len());
        }

        fn can_read_everything() {
            let pipe = Pipe::new();
            pipe.write(b"hello").unwrap();
            test_read(&pipe, b"hello");
            assert_eq!(0, pipe.queue_len());
        }

        fn blocks_when_out_of_data() {
            let pipe = Pipe::new();
            pipe.write(b"hello").unwrap();

            let d = pipe.read_async(vec![0; 10]);
            assert!(d.try_get().is_err());
        }

        fn can_write_twice() {
            let pipe = Pipe::new();
            pipe.write(b"hello ").unwrap();
            test_read(&pipe, b"hel");
            pipe.write(b"world").unwrap();
            test_read(&pipe, b"lo wo");
            test_read(&pipe, b"r");
            assert_eq!(2, pipe.queue_len());
        }
    }
}