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easy_lock.h 3.2 KB

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  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. #include "curl_setup.h"
  27. #define GLOBAL_INIT_IS_THREADSAFE
  28. #if defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x600
  29. #ifdef __MINGW32__
  30. #ifndef SRWLOCK_INIT
  31. #define SRWLOCK_INIT NULL
  32. #endif
  33. #endif /* __MINGW32__ */
  34. #define curl_simple_lock SRWLOCK
  35. #define CURL_SIMPLE_LOCK_INIT SRWLOCK_INIT
  36. #define curl_simple_lock_lock(m) AcquireSRWLockExclusive(m)
  37. #define curl_simple_lock_unlock(m) ReleaseSRWLockExclusive(m)
  38. #elif defined(HAVE_ATOMIC) && defined(HAVE_STDATOMIC_H)
  39. #include <stdatomic.h>
  40. #if defined(HAVE_SCHED_YIELD)
  41. #include <sched.h>
  42. #endif
  43. #define curl_simple_lock atomic_int
  44. #define CURL_SIMPLE_LOCK_INIT 0
  45. /* a clang-thing */
  46. #ifndef __has_builtin
  47. #define __has_builtin(x) 0
  48. #endif
  49. #ifndef __INTEL_COMPILER
  50. /* The Intel compiler tries to look like GCC *and* clang *and* lies in its
  51. __has_builtin() function, so override it. */
  52. /* if GCC on i386/x86_64 or if the built-in is present */
  53. #if ( (defined(__GNUC__) && !defined(__clang__)) && \
  54. (defined(__i386__) || defined(__x86_64__))) || \
  55. __has_builtin(__builtin_ia32_pause)
  56. #define HAVE_BUILTIN_IA32_PAUSE
  57. #endif
  58. #endif
  59. static inline void curl_simple_lock_lock(curl_simple_lock *lock)
  60. {
  61. for(;;) {
  62. if(!atomic_exchange_explicit(lock, true, memory_order_acquire))
  63. break;
  64. /* Reduce cache coherency traffic */
  65. while(atomic_load_explicit(lock, memory_order_relaxed)) {
  66. /* Reduce load (not mandatory) */
  67. #ifdef HAVE_BUILTIN_IA32_PAUSE
  68. __builtin_ia32_pause();
  69. #elif defined(__aarch64__)
  70. __asm__ volatile("yield" ::: "memory");
  71. #elif defined(HAVE_SCHED_YIELD)
  72. sched_yield();
  73. #endif
  74. }
  75. }
  76. }
  77. static inline void curl_simple_lock_unlock(curl_simple_lock *lock)
  78. {
  79. atomic_store_explicit(lock, false, memory_order_release);
  80. }
  81. #elif defined(USE_THREADS_POSIX) && defined(HAVE_PTHREAD_H)
  82. #include <pthread.h>
  83. #define curl_simple_lock pthread_mutex_t
  84. #define CURL_SIMPLE_LOCK_INIT PTHREAD_MUTEX_INITIALIZER
  85. #define curl_simple_lock_lock(m) pthread_mutex_lock(m)
  86. #define curl_simple_lock_unlock(m) pthread_mutex_unlock(m)
  87. #else
  88. #undef GLOBAL_INIT_IS_THREADSAFE
  89. #endif
  90. #endif /* HEADER_CURL_EASY_LOCK_H */