o3 0.7.0

shared-nothing primitives
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
153
154
155

use std::mem::{needs_drop, size_of};

use o3::buffer::{
    Borrowed, ByteSpan, Bytes, Leased, Pooled, RetainBytes, Retained, Shared, SharedPool,
};

fn span(value: &impl ByteSpan) -> &[u8] {
    value.as_slice()
}

#[test]
fn borrowed_bytes_are_a_transparent_slice() {
    assert_eq!(size_of::<Bytes<Borrowed<'_>>>(), size_of::<&[u8]>());
    assert!(!needs_drop::<Bytes<Borrowed<'_>>>());

    let bytes = Bytes::<Borrowed<'_>>::from(b"abcdef");
    assert_eq!(span(&bytes), b"abcdef");
    assert_eq!(bytes.len(), 6);
    assert!(!bytes.is_empty());
}

#[test]
fn borrowed_slice_stays_borrowed() {
    let bytes = Bytes::<Borrowed<'_>>::from(b"abcdef").slice(1..5);
    assert_eq!(bytes.as_slice(), b"bcde");
    assert_eq!(bytes.slice(1..3).as_slice(), b"cd");
}

#[test]
fn borrowed_retention_is_an_explicit_copy() {
    let source = [1, 2, 3, 4];
    let retained = RetainBytes::into_retained(Bytes::<Borrowed<'_>>::from(&source));
    assert_eq!(retained.as_slice(), source);
}

#[test]
fn leased_retention_transfers_the_pool_slot_without_copying() {
    assert_eq!(size_of::<Bytes<Leased>>(), size_of::<Pooled>());

    let pool = SharedPool::new(1, 16);
    let mut lease = pool.try_acquire().expect("pool slot");
    lease
        .spare_writer()
        .try_extend_from_slice(b"leased")
        .expect("slot capacity");
    let source = lease.as_slice().as_ptr();
    let bytes = Bytes::<Leased>::from(lease.freeze());

    assert_eq!(bytes.as_slice(), b"leased");
    assert_eq!(bytes.as_slice().as_ptr(), source);
    assert_eq!(pool.available(), 0);

    let retained = bytes.into_retained();
    assert_eq!(retained.as_slice().as_ptr(), source);
    assert_eq!(pool.available(), 0);
    drop(retained);
    assert_eq!(pool.available(), 1);
}

#[test]
fn pooled_ranges_enter_owned_storage_directly() {
    let pool = SharedPool::new(1, 16);
    let mut lease = pool.try_acquire().expect("pool slot");
    lease
        .spare_writer()
        .try_extend_from_slice(b"abcdef")
        .expect("slot capacity");
    let source = lease.as_slice()[1..5].as_ptr();

    let retained = Bytes::<Retained>::from(lease.freeze()).slice(1..5);
    assert_eq!(retained.as_slice(), b"bcde");
    assert_eq!(retained.as_slice().as_ptr(), source);
    assert_eq!(pool.available(), 0);
    drop(retained);
    assert_eq!(pool.available(), 1);
}

#[test]
fn empty_pooled_slice_releases_its_slot() {
    let pool = SharedPool::new(1, 8);
    let mut lease = pool.try_acquire().expect("pool slot");
    lease
        .spare_writer()
        .try_extend_from_slice(b"abcdef")
        .expect("slot capacity");

    let bytes = Bytes::<Retained>::from(lease.freeze());
    assert_eq!(pool.available(), 0);
    let empty = bytes.slice(3..3);
    assert!(empty.is_empty());
    assert_eq!(pool.available(), 1);
}

#[test]
fn shared_bytes_slice_and_retain_without_changing_storage_class() {
    assert_eq!(size_of::<Bytes<Shared>>(), size_of::<Shared>());

    let shared = Shared::copy_from_slice(b"abcdef");
    let source = shared.as_slice()[1..5].as_ptr();
    let bytes = Bytes::<Shared>::from(shared).slice(1..5);
    assert_eq!(bytes.as_slice(), b"bcde");
    assert_eq!(bytes.as_slice().as_ptr(), source);

    let retained = bytes.into_retained();
    assert_eq!(retained.as_slice(), b"bcde");
    assert_eq!(retained.as_slice().as_ptr(), source);
}

#[cfg(target_pointer_width = "64")]
#[test]
fn retained_storage_stays_compact() {
    assert_eq!(size_of::<Bytes<Retained>>(), 32);
}

#[test]
fn retained_storage_advances_and_slices_without_copying() {
    let pool = SharedPool::new(1, 8);
    let mut lease = pool.try_acquire().expect("pool slot");
    lease
        .spare_writer()
        .try_extend_from_slice(b"abcdef")
        .expect("slot capacity");
    let source = lease.as_slice().as_ptr();
    let mut retained = Bytes::<Retained>::from(lease.freeze()).slice(1..5);

    assert_eq!(retained.as_slice(), b"bcde");
    assert_eq!(retained.as_slice().as_ptr(), source.wrapping_add(1));
    assert_eq!(pool.available(), 0);
    retained.advance(1);
    assert_eq!(retained.as_slice(), b"cde");
    assert_eq!(retained.as_slice().as_ptr(), source.wrapping_add(2));
    drop(retained);
    assert_eq!(pool.available(), 1);
}

#[test]
fn latest_byte_policies_reject_invalid_ranges() {
    let shared = Shared::copy_from_slice(b"abcdef");
    let reversed = [2, 1];
    let invalid = [
        std::panic::catch_unwind(|| {
            Bytes::<Borrowed<'_>>::from(b"abc").slice(reversed[0]..reversed[1])
        })
        .is_err(),
        std::panic::catch_unwind(|| Bytes::<Retained>::from(shared.clone()).slice(1..7)).is_err(),
        std::panic::catch_unwind(|| {
            Bytes::<Borrowed<'_>>::from(b"abcdef")
                .slice(1..4)
                .slice(0..4)
        })
        .is_err(),
        std::panic::catch_unwind(|| Bytes::<Retained>::from(shared.clone()).slice(0..7)).is_err(),
    ];
    assert!(invalid.into_iter().all(|rejected| rejected));
}