blob: a7ec5ec8cc8318b1dc1bb6dfcf1db7abd1725b8b (
plain)
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
|
/* Copyright (C) 2023 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/*!
* \brief A C11 spinlock (POSIX pthread spinlock as a fallback).
*/
#pragma once
#if (__STDC_VERSION__ >= 201112L) && !defined(__STDC_NO_ATOMICS__)
#define HAVE_STDATOMIC
#include <stdatomic.h>
#include <stdbool.h>
#else /* POSIX pthread spinlock. */
#include <pthread.h>
#endif
/*! \brief Spinlock lock variable type. */
typedef
#if defined(HAVE_STDATOMIC)
atomic_bool /*!< Spinlock lock - a simple & fast atomic version, C11 */
#else /* POSIX */
pthread_spinlock_t /*!< Spinlock lock - a POSIX pthread version. */
#endif
knot_spin_t;
/*! \brief Initialize the spinlock pointed to by the parameter "lock". */
static inline void knot_spin_init(knot_spin_t *lock)
{
#if defined(HAVE_STDATOMIC)
atomic_init(lock, false);
#else /* POSIX */
pthread_spin_init(lock, PTHREAD_PROCESS_PRIVATE);
#endif
}
/*! \brief Destroy the spinlock pointed to by the parameter "lock". */
static inline void knot_spin_destroy(knot_spin_t *lock)
{
#if defined(HAVE_STDATOMIC)
/* Nothing needed here. */
#else /* POSIX */
pthread_spin_destroy(lock);
#endif
}
/*! \brief Lock the spinlock pointed to by the parameter "lock". */
static inline void knot_spin_lock(knot_spin_t *lock)
{
#if defined(HAVE_STDATOMIC)
bool expected = false;
while (!atomic_compare_exchange_strong(lock, &expected, true)) {
expected = false;
}
#else /* POSIX */
pthread_spin_lock(lock);
#endif
}
/*! \brief Unlock the spinlock pointed to by the parameter "lock". */
static inline void knot_spin_unlock(knot_spin_t *lock)
{
#if defined(HAVE_STDATOMIC)
atomic_store(lock, false);
#else /* POSIX */
pthread_spin_unlock(lock);
#endif
}
|
