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

//! Slice data structure for interacting with rocksdb keys and values.

use std::fmt;
use std::ops;
use std::slice;

use rocks_sys as ll;

use crate::to_raw::ToRaw;

/// A Slice that can be pinned with some cleanup tasks, which will be run upon
/// `::Reset()` or object destruction, whichever is invoked first. This can be used
/// to avoid memcpy by having the `PinnsableSlice` object referring to the data
/// that is locked in the memory and release them after the data is consuned.
pub struct PinnableSlice {
    raw: *mut ll::rocks_pinnable_slice_t,
}

impl ToRaw<ll::rocks_pinnable_slice_t> for PinnableSlice {
    fn raw(&self) -> *mut ll::rocks_pinnable_slice_t {
        self.raw
    }
}

impl Drop for PinnableSlice {
    fn drop(&mut self) {
        unsafe {
            ll::rocks_pinnable_slice_destroy(self.raw);
        }
    }
}

impl PinnableSlice {
    pub fn new() -> PinnableSlice {
        PinnableSlice {
            raw: unsafe { ll::rocks_pinnable_slice_create() },
        }
    }

    #[inline]
    pub fn data(&self) -> *const u8 {
        unsafe { ll::rocks_pinnable_slice_data(self.raw) as *const u8 }
    }

    #[inline]
    pub fn size(&self) -> usize {
        unsafe { ll::rocks_pinnable_slice_size(self.raw) as usize }
    }
}

impl fmt::Debug for PinnableSlice {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let s = unsafe { slice::from_raw_parts(self.data(), self.len()) };
        write!(f, "{:?}", String::from_utf8_lossy(s))
    }
}

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

impl ops::Deref for PinnableSlice {
    type Target = [u8];
    fn deref(&self) -> &[u8] {
        unsafe { slice::from_raw_parts(self.data(), self.size()) }
    }
}

impl AsRef<[u8]> for PinnableSlice {
    fn as_ref(&self) -> &[u8] {
        unsafe { slice::from_raw_parts(self.data(), self.len()) }
    }
}

impl<'a> PartialEq<&'a [u8]> for PinnableSlice {
    fn eq(&self, rhs: &&[u8]) -> bool {
        &self.as_ref() == rhs
    }
}

impl<'a, 'b> PartialEq<&'b [u8]> for &'a PinnableSlice {
    fn eq(&self, rhs: &&[u8]) -> bool {
        &self.as_ref() == rhs
    }
}

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

    #[test]
    fn pinnable_slice() {
        let s = PinnableSlice::new();
        assert_eq!(s, b"");
        assert_eq!(&format!("{:?}", s), "\"\"");
    }
}