mmap-vec 0.2.0

Memory mapped vectors
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

use std::{io, marker::PhantomData, mem};

use crate::{
    utils::{check_zst, page_size},
    DefaultSegmentBuilder, MmapVec, Segment, SegmentBuilder,
};

/// Helps to create vec with custom parameters.
///
/// Example usage:
///
/// ```rust
/// # use mmap_vec::{DefaultSegmentBuilder, MmapVecBuilder};
/// let seg_builder = DefaultSegmentBuilder::with_path("/tmp/rust-mmap");
/// seg_builder.create_dir_all().expect("Fail to create mmap dir");
///
/// let vec = MmapVecBuilder::<usize>::new()
///     .capacity(500)
///     .segment_builder(seg_builder.clone())
///     .try_build()
///     .expect("Fail to create mmap vec");
/// ```
pub struct MmapVecBuilder<T, SB: SegmentBuilder = DefaultSegmentBuilder> {
    segment_builder: SB,
    capacity: usize,
    _phantom: PhantomData<T>,
}

impl<T, SB: SegmentBuilder> MmapVecBuilder<T, SB> {
    /// Create new struct.
    #[inline(always)]
    pub fn new() -> Self {
        Self::default()
    }

    /// Update segment builder.
    #[inline(always)]
    pub fn segment_builder(mut self, segment_builder: SB) -> Self {
        self.segment_builder = segment_builder;
        self
    }

    /// Update capacity.
    #[inline(always)]
    pub fn capacity(mut self, capacity: usize) -> Self {
        self.capacity = capacity;
        self
    }

    /// Try building a new vec with given parameter.
    ///
    /// This function may failed if segment creation failed.
    pub fn try_build(self) -> io::Result<MmapVec<T, SB>> {
        let path = self.segment_builder.new_segment_path();
        let segment = Segment::open_rw(&path, self.capacity)?;

        Ok(MmapVec {
            segment,
            builder: self.segment_builder,
            path,
        })
    }
}

impl<T, SB: SegmentBuilder> Default for MmapVecBuilder<T, SB> {
    #[inline(always)]
    fn default() -> Self {
        check_zst::<T>();
        Self {
            segment_builder: SB::default(),
            capacity: page_size() / mem::size_of::<T>(),
            _phantom: PhantomData,
        }
    }
}