# buf.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/hyper-0.14.4/src/common/buf.rs`.
Keywords: rust, rustlang, rust-lang

      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

    use std::collections::VecDeque;
    use std::io::IoSlice;

    use bytes::{Buf, BufMut, Bytes, BytesMut};

    pub(crate) struct BufList<T> {
        bufs: VecDeque<T>,
    }

    impl<T: Buf> BufList<T> {
        pub(crate) fn new() -> BufList<T> {
            BufList {
                bufs: VecDeque::new(),
            }
        }

        #[inline]
        pub(crate) fn push(&mut self, buf: T) {
            debug_assert!(buf.has_remaining());
            self.bufs.push_back(buf);
        }

        #[inline]
        #[cfg(feature = "http1")]
        pub(crate) fn bufs_cnt(&self) -> usize {
            self.bufs.len()
        }
    }

    impl<T: Buf> Buf for BufList<T> {
        #[inline]
        fn remaining(&self) -> usize {
            self.bufs.iter().map(|buf| buf.remaining()).sum()
        }

        #[inline]
        fn chunk(&self) -> &[u8] {
            self.bufs.front().map(Buf::chunk).unwrap_or_default()
        }

        #[inline]
        fn advance(&mut self, mut cnt: usize) {
            while cnt > 0 {
                {
                    let front = &mut self.bufs[0];
                    let rem = front.remaining();
                    if rem > cnt {
                        front.advance(cnt);
                        return;
                    } else {
                        front.advance(rem);
                        cnt -= rem;
                    }
                }
                self.bufs.pop_front();
            }
        }

        #[inline]
        fn chunks_vectored<'t>(&'t self, dst: &mut [IoSlice<'t>]) -> usize {
            if dst.is_empty() {
                return 0;
            }
            let mut vecs = 0;
            for buf in &self.bufs {
                vecs += buf.chunks_vectored(&mut dst[vecs..]);
                if vecs == dst.len() {
                    break;
                }
            }
            vecs
        }

        #[inline]
        fn copy_to_bytes(&mut self, len: usize) -> Bytes {
            // Our inner buffer may have an optimized version of copy_to_bytes, and if the whole
            // request can be fulfilled by the front buffer, we can take advantage.
            match self.bufs.front_mut() {
                Some(front) if front.remaining() == len => {
                    let b = front.copy_to_bytes(len);
                    self.bufs.pop_front();
                    b
                }
                Some(front) if front.remaining() > len => front.copy_to_bytes(len),
                _ => {
                    assert!(len <= self.remaining(), "`len` greater than remaining");
                    let mut bm = BytesMut::with_capacity(len);
                    bm.put(self.take(len));
                    bm.freeze()
                }
            }
        }
    }

    #[cfg(test)]
    mod tests {
        use std::ptr;

        use super::*;

        fn hello_world_buf() -> BufList<Bytes> {
            BufList {
                bufs: vec![Bytes::from("Hello"), Bytes::from(" "), Bytes::from("World")].into(),
            }
        }

        #[test]
        fn to_bytes_shorter() {
            let mut bufs = hello_world_buf();
            let old_ptr = bufs.chunk().as_ptr();
            let start = bufs.copy_to_bytes(4);
            assert_eq!(start, "Hell");
            assert!(ptr::eq(old_ptr, start.as_ptr()));
            assert_eq!(bufs.chunk(), b"o");
            assert!(ptr::eq(old_ptr.wrapping_add(4), bufs.chunk().as_ptr()));
            assert_eq!(bufs.remaining(), 7);
        }

        #[test]
        fn to_bytes_eq() {
            let mut bufs = hello_world_buf();
            let old_ptr = bufs.chunk().as_ptr();
            let start = bufs.copy_to_bytes(5);
            assert_eq!(start, "Hello");
            assert!(ptr::eq(old_ptr, start.as_ptr()));
            assert_eq!(bufs.chunk(), b" ");
            assert_eq!(bufs.remaining(), 6);
        }

        #[test]
        fn to_bytes_longer() {
            let mut bufs = hello_world_buf();
            let start = bufs.copy_to_bytes(7);
            assert_eq!(start, "Hello W");
            assert_eq!(bufs.remaining(), 4);
        }

        #[test]
        fn one_long_buf_to_bytes() {
            let mut buf = BufList::new();
            buf.push(b"Hello World" as &[_]);
            assert_eq!(buf.copy_to_bytes(5), "Hello");
            assert_eq!(buf.chunk(), b" World");
        }

        #[test]
        #[should_panic(expected = "`len` greater than remaining")]
        fn buf_to_bytes_too_many() {
            hello_world_buf().copy_to_bytes(42);
        }
    }