marble 16.0.2

garbage-collecting on-disk object store
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
76
77
78
79
80
81
82
83
84
85
86
87
88

use std::num::NonZeroU64;

fn shift_location(location: u64, is_delete: bool) -> u64 {
    assert_eq!(location << 1 >> 1, location);
    let inner = if is_delete {
        (location << 1) + 1
    } else {
        location << 1
    };

    inner
}

fn unshift_location(location: u64) -> (u64, bool) {
    if location % 2 == 1 {
        (location >> 1, true)
    } else {
        (location >> 1, false)
    }
}

#[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash)]
#[repr(transparent)]
pub struct RelativeDiskLocation(u64);

impl RelativeDiskLocation {
    pub fn new(offset: u64, is_delete: bool) -> RelativeDiskLocation {
        RelativeDiskLocation(shift_location(offset, is_delete))
    }

    pub fn to_raw(&self) -> u64 {
        self.0
    }

    pub fn from_raw(raw: u64) -> RelativeDiskLocation {
        RelativeDiskLocation(raw)
    }

    pub fn to_absolute(&self, base: u64) -> DiskLocation {
        let (offset, is_delete) = unshift_location(self.0);
        let absolute = offset.checked_add(base).unwrap();
        DiskLocation::new(absolute, is_delete)
    }

    fn unshift(&self) -> (u64, bool) {
        unshift_location(self.0)
    }

    pub fn is_delete(&self) -> bool {
        self.unshift().1
    }
}

#[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash)]
#[repr(transparent)]
pub struct DiskLocation(NonZeroU64);

impl DiskLocation {
    pub const MAX: DiskLocation = DiskLocation(unsafe { NonZeroU64::new_unchecked(u64::MAX) });

    pub fn new(location: u64, is_delete: bool) -> DiskLocation {
        DiskLocation(NonZeroU64::new(shift_location(location, is_delete)).unwrap())
    }

    pub fn new_fam(location: u64) -> DiskLocation {
        DiskLocation::new(location, false)
    }

    pub fn from_raw(u: u64) -> Option<DiskLocation> {
        Some(DiskLocation(NonZeroU64::new(u)?))
    }

    pub fn to_raw(&self) -> u64 {
        self.0.get()
    }

    fn unshift(&self) -> (u64, bool) {
        unshift_location(self.0.get())
    }

    pub fn lsn(&self) -> u64 {
        self.unshift().0
    }

    pub fn is_delete(&self) -> bool {
        self.unshift().1
    }
}