fly 0.2.0

Convergent Replicated Data Types in Rust
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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152

use std::collections::HashSet;
use std::hash::Hash;
use crdt::Crdt;
use std::fmt::Debug;

pub struct GSet<E> {
    data: HashSet<E>,
}

impl<E> GSet<E>
    where E: Eq + Hash + Clone
{
    pub fn new() -> GSet<E> {
        GSet { data: HashSet::new() }
    }

    pub fn add(&mut self, el: E) {
        self.data.insert(el);
    }
}

impl<E> Crdt for GSet<E>
    where E: Eq + Hash + Clone
{
    fn merge(&self, other: &GSet<E>) -> GSet<E> {
        let mut set = HashSet::new();

        for el in self.data.union(&other.data) {
            set.insert(el.clone());
        }

        GSet { data: set }
    }
}

pub struct TwoPSet<E> {
    p: HashSet<E>,
    n: HashSet<E>,
}

impl<E> TwoPSet<E>
    where E: Eq + Hash + Clone
{
    pub fn new() -> TwoPSet<E> {
        TwoPSet {
            p: HashSet::new(),
            n: HashSet::new()
        }
    }

    pub fn add(&mut self, key: E) {
        self.p.insert(key);
    }

    pub fn remove(&mut self, key: E) {
        self.n.insert(key);
    }
}

impl<E> Crdt for TwoPSet<E>
    where E: Eq + Hash + Clone
{
    fn merge(&self, other: &TwoPSet<E>) -> TwoPSet<E> {
        let mut pset = HashSet::new();
        let mut nset = HashSet::new();

        // Merge the two N sets
        for n in self.n.union(&other.n) {
            nset.insert(n.clone());
        }

        // Merge the two P sets
        for p in self.p.union(&other.p) {
            // Only merge the set if it's not in the converged N set.
            if !nset.contains(p) {
                pset.insert(p.clone());
            }
        }

        TwoPSet {
            p: pset,
            n: HashSet::new()
        }
    }
}

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

    #[test]
    fn merge_gset() {
        let mut a = GSet::new();
        let mut b = GSet::new();

        a.add("foobar");
        b.add("bigya");

        let c = a.merge(&b);

        assert_eq!(c.data.len(), 2);
        assert_eq!(c.data.contains("foobar"), true);
        assert_eq!(c.data.contains("bigya"), true);
    }

    #[test]
    fn merge_twopset() {
        let mut a = TwoPSet::new();
        let mut b = TwoPSet::new();

        a.add("foobar");
        b.remove("foobar");

        let c = a.merge(&b);

        assert_eq!(c.p.len(), 0);
        assert_eq!(c.n.len(), 0);
    }

    #[test]
    fn merge_twopset_remove_priority() {

        let mut a = TwoPSet::new();
        let mut b = TwoPSet::new();

        a.add("foobar");
        b.remove("foobar");
        b.add("foobar");

        let c = a.merge(&b);

        assert_eq!(c.p.len(), 0);
        assert_eq!(c.n.len(), 0);
    }

    #[test]
    fn merge_twopset_remove_add() {

        let mut a = TwoPSet::new();
        let mut b = TwoPSet::new();

        a.add("foobar");
        b.remove("foobar");
        b.add("foobar1");

        let c = a.merge(&b);

        assert_eq!(c.p.len(), 1);
        assert_eq!(c.n.len(), 0);
    }
}