1 #ifndef HEADER_CURL_EASY_LOCK_H
2 #define HEADER_CURL_EASY_LOCK_H
3 /***************************************************************************
4 * _ _ ____ _
5 * Project ___| | | | _ \| |
6 * / __| | | | |_) | |
7 * | (__| |_| | _ <| |___
8 * \___|\___/|_| \_\_____|
9 *
10 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
11 *
12 * This software is licensed as described in the file COPYING, which
13 * you should have received as part of this distribution. The terms
14 * are also available at https://curl.se/docs/copyright.html.
15 *
16 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
17 * copies of the Software, and permit persons to whom the Software is
18 * furnished to do so, under the terms of the COPYING file.
19 *
20 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
21 * KIND, either express or implied.
22 *
23 * SPDX-License-Identifier: curl
24 *
25 ***************************************************************************/
26
27 #include "curl_setup.h"
28
29 #define GLOBAL_INIT_IS_THREADSAFE
30
31 #if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600
32
33 #ifdef __MINGW32__
34 #ifndef SRWLOCK_INIT
35 #define SRWLOCK_INIT NULL
36 #endif
37 #endif /* __MINGW32__ */
38
39 #define curl_simple_lock SRWLOCK
40 #define CURL_SIMPLE_LOCK_INIT SRWLOCK_INIT
41
42 #define curl_simple_lock_lock(m) AcquireSRWLockExclusive(m)
43 #define curl_simple_lock_unlock(m) ReleaseSRWLockExclusive(m)
44
45 #elif defined(HAVE_ATOMIC) && defined(HAVE_STDATOMIC_H)
46 #include <stdatomic.h>
47 #if defined(HAVE_SCHED_YIELD)
48 #include <sched.h>
49 #endif
50
51 #define curl_simple_lock atomic_int
52 #define CURL_SIMPLE_LOCK_INIT 0
53
54 /* a clang-thing */
55 #ifndef __has_builtin
56 #define __has_builtin(x) 0
57 #endif
58
59 #ifndef __INTEL_COMPILER
60 /* The Intel compiler tries to look like GCC *and* clang *and* lies in its
61 __has_builtin() function, so override it. */
62
63 /* if GCC on i386/x86_64 or if the built-in is present */
64 #if ( (defined(__GNUC__) && !defined(__clang__)) && \
65 (defined(__i386__) || defined(__x86_64__))) || \
66 __has_builtin(__builtin_ia32_pause)
67 #define HAVE_BUILTIN_IA32_PAUSE
68 #endif
69
70 #endif
71
curl_simple_lock_lock(curl_simple_lock * lock)72 static inline void curl_simple_lock_lock(curl_simple_lock *lock)
73 {
74 for(;;) {
75 if(!atomic_exchange_explicit(lock, true, memory_order_acquire))
76 break;
77 /* Reduce cache coherency traffic */
78 while(atomic_load_explicit(lock, memory_order_relaxed)) {
79 /* Reduce load (not mandatory) */
80 #ifdef HAVE_BUILTIN_IA32_PAUSE
81 __builtin_ia32_pause();
82 #elif defined(__aarch64__)
83 __asm__ volatile("yield" ::: "memory");
84 #elif defined(HAVE_SCHED_YIELD)
85 sched_yield();
86 #endif
87 }
88 }
89 }
90
curl_simple_lock_unlock(curl_simple_lock * lock)91 static inline void curl_simple_lock_unlock(curl_simple_lock *lock)
92 {
93 atomic_store_explicit(lock, false, memory_order_release);
94 }
95
96 #elif defined(USE_THREADS_POSIX) && defined(HAVE_PTHREAD_H)
97
98 #include <pthread.h>
99
100 #define curl_simple_lock pthread_mutex_t
101 #define CURL_SIMPLE_LOCK_INIT PTHREAD_MUTEX_INITIALIZER
102 #define curl_simple_lock_lock(m) pthread_mutex_lock(m)
103 #define curl_simple_lock_unlock(m) pthread_mutex_unlock(m)
104
105 #else
106
107 #undef GLOBAL_INIT_IS_THREADSAFE
108
109 #endif
110
111 #endif /* HEADER_CURL_EASY_LOCK_H */
112