nolock 0.4.1

A collection of Lock-Free Datastructures
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
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

use alloc::boxed::Box;
use core::fmt::Debug;

mod level;
use level::Level;

mod entry;
use entry::Entry;

mod ptr;
use ptr::{CustomPtr, PtrTarget};

use crate::thread_data::StorageBackend;

/// A Lock-Free Trie that can be used as the StorageBackend for Thread-Local-Data
pub struct Trie<T> {
    // The Pointer to the first Level
    initial_ptr: *mut Level<T>,
}

impl<T> Debug for Trie<T>
where
    T: Debug,
{
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        // Safety:
        // This is save to do because we create the Pointer when creating the
        // Trie meaning it is always going to be a valid pointer to a Level.
        // The Memory being pointed to is also still valid because we only
        // deallocate it once the Trie is dropped.
        let initial_level = unsafe { &*self.initial_ptr };
        write!(f, "Trie ({:?})", initial_level)
    }
}

impl<T> Trie<T> {
    /// Creates a new Trie instance
    pub fn new() -> Self {
        let initial_level = Level::new(0, 3, core::ptr::null());

        Self {
            initial_ptr: Box::into_raw(initial_level),
        }
    }
}

impl<T> StorageBackend<T> for Trie<T> {
    fn get(&self, id: u64) -> Option<&T> {
        // This simply "forwards" the get to the first initial Level of the
        // Trie

        // Safety:
        // This is save to do because we create the Pointer when creating the
        // Trie meaning it is always going to be a valid pointer to a Level.
        // The Memory being pointed to is also still valid because we only
        // deallocate it once the Trie is dropped.
        let level = unsafe { &*self.initial_ptr };
        level.get(id)
    }

    fn insert(&self, id: u64, data: T) -> &T {
        // This simply "forwards" the insert to the first initial Level of the
        // Trie

        // Safety:
        // This is save to do because we create the Pointer when creating the
        // Trie meaning it is always going to be a valid pointer to a Level.
        // The Memory being pointed to is also still valid because we only
        // deallocate it once the Trie is dropped.
        let level = unsafe { &*self.initial_ptr };
        level.insert(id, data)
    }
}

impl<T> Default for Trie<T> {
    fn default() -> Self {
        Self::new()
    }
}

impl<T> Drop for Trie<T> {
    fn drop(&mut self) {
        unsafe { Box::from_raw(self.initial_ptr) };
    }
}

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

    #[test]
    fn new() {
        Trie::<usize>::new();
    }

    #[test]
    fn get_empty() {
        let trie = Trie::<usize>::new();

        assert_eq!(None, trie.get(123));
        drop(trie);
    }

    #[test]
    fn insert() {
        let trie = Trie::<usize>::new();

        let value = trie.insert(123, 13);
        assert_eq!(13, *value);
    }

    #[test]
    fn insert_get() {
        let trie = Trie::<usize>::new();

        let value = trie.insert(123, 13);
        assert_eq!(13, *value);

        let result = trie.get(123);
        assert_eq!(Some(&13), result);
    }

    #[test]
    fn insert_get_colliding() {
        let trie = Trie::<usize>::new();

        assert_eq!(13, *trie.insert(0x1234, 13));
        assert_eq!(14, *trie.insert(0x1334, 14));
        assert_eq!(15, *trie.insert(0x1434, 15));

        assert_eq!(Some(&13), trie.get(0x1234));
        assert_eq!(Some(&14), trie.get(0x1334));
        assert_eq!(Some(&15), trie.get(0x1434));
    }
}