[go: up one dir, main page]

atomic 0.3.3

Generic Atomic<T> wrapper type
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
156
157
158
159
160
161

// Copyright 2016 Amanieu d'Antras
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

use core::mem;
use core::ops;
use core::num::Wrapping;
use core::sync::atomic::{Ordering, AtomicUsize};

mod fallback;

#[inline]
pub fn atomic_is_lock_free<T>() -> bool {
    mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
    mem::align_of::<T>() >= mem::size_of::<AtomicUsize>()
}

#[inline]
pub unsafe fn atomic_load<T>(dst: *mut T, order: Ordering) -> T {
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        mem::transmute_copy(&a.load(order))
    } else {
        fallback::atomic_load(dst)
    }
}

#[inline]
pub unsafe fn atomic_store<T>(dst: *mut T, val: T, order: Ordering) {
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        a.store(mem::transmute_copy(&val), order);
    } else {
        fallback::atomic_store(dst, val);
    }
}

#[inline]
pub unsafe fn atomic_swap<T>(dst: *mut T, val: T, order: Ordering) -> T {
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        mem::transmute_copy(&a.swap(mem::transmute_copy(&val), order))
    } else {
        fallback::atomic_swap(dst, val)
    }
}

#[inline]
pub unsafe fn atomic_compare_exchange<T>(dst: *mut T,
                                         current: T,
                                         new: T,
                                         success: Ordering,
                                         _: Ordering)
                                         -> Result<T, T> {
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        let current_val: usize = mem::transmute_copy(&current);
        let result_val = a.compare_and_swap(current_val, mem::transmute_copy(&new), success);
        if current_val == result_val {
            Ok(mem::transmute_copy(&result_val))
        } else {
            Err(mem::transmute_copy(&result_val))
        }
    } else {
        fallback::atomic_compare_exchange(dst, current, new)
    }
}

#[inline]
pub unsafe fn atomic_compare_exchange_weak<T>(dst: *mut T,
                                              current: T,
                                              new: T,
                                              success: Ordering,
                                              failure: Ordering)
                                              -> Result<T, T> {
    atomic_compare_exchange(dst, current, new, success, failure)
}

#[inline]
pub unsafe fn atomic_add<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T
    where Wrapping<T>: ops::Add<Output = Wrapping<T>>
{
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        mem::transmute_copy(&a.fetch_add(mem::transmute_copy(&val), order))
    } else {
        fallback::atomic_add(dst, val)
    }
}

#[inline]
pub unsafe fn atomic_sub<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T
    where Wrapping<T>: ops::Sub<Output = Wrapping<T>>
{
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        mem::transmute_copy(&a.fetch_sub(mem::transmute_copy(&val), order))
    } else {
        fallback::atomic_sub(dst, val)
    }
}

#[inline]
pub unsafe fn atomic_and<T: Copy + ops::BitAnd<Output = T>>(dst: *mut T,
                                                            val: T,
                                                            order: Ordering)
                                                            -> T {
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        mem::transmute_copy(&a.fetch_and(mem::transmute_copy(&val), order))
    } else {
        fallback::atomic_and(dst, val)
    }
}

#[inline]
pub unsafe fn atomic_or<T: Copy + ops::BitOr<Output = T>>(dst: *mut T,
                                                          val: T,
                                                          order: Ordering)
                                                          -> T {
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        mem::transmute_copy(&a.fetch_or(mem::transmute_copy(&val), order))
    } else {
        fallback::atomic_or(dst, val)
    }
}

#[inline]
pub unsafe fn atomic_xor<T: Copy + ops::BitXor<Output = T>>(dst: *mut T,
                                                            val: T,
                                                            order: Ordering)
                                                            -> T {
    if mem::size_of::<T>() == mem::size_of::<AtomicUsize>() &&
       mem::align_of::<T>() >= mem::size_of::<AtomicUsize>() {
        assert_eq!(mem::size_of::<AtomicUsize>(), mem::size_of::<usize>());
        let a = &*(dst as *const AtomicUsize);
        mem::transmute_copy(&a.fetch_xor(mem::transmute_copy(&val), order))
    } else {
        fallback::atomic_xor(dst, val)
    }
}