src/thread-utils.h

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7 #ifndef INCLUDE_thread_utils_h__
   8 #define INCLUDE_thread_utils_h__
   9
  10 #include "common.h"
  11
  12 /* Common operations even if threading has been disabled */
  13 typedef struct {
  14 #if defined(GIT_WIN32)
  15         volatile long val;
  16 #else
  17         volatile int val;
  18 #endif
  19 } git_atomic;
  20
  21 GIT_INLINE(void) git_atomic_set(git_atomic *a, int val)
  22 {
  23         a->val = val;
  24 }
  25
  26 #ifdef GIT_THREADS
  27
  28 #define git_thread pthread_t
  29 #define git_thread_create(thread, attr, start_routine, arg) pthread_create(thread, attr, start_routine, arg)
  30 #define git_thread_kill(thread) pthread_cancel(thread)
  31 #define git_thread_exit(status) pthread_exit(status)
  32 #define git_thread_join(id, status) pthread_join(id, status)
  33
  34 /* Pthreads Mutex */
  35 #define git_mutex pthread_mutex_t
  36 #define git_mutex_init(a)       pthread_mutex_init(a, NULL)
  37 #define git_mutex_lock(a)       pthread_mutex_lock(a)
  38 #define git_mutex_unlock(a) pthread_mutex_unlock(a)
  39 #define git_mutex_free(a)       pthread_mutex_destroy(a)
  40
  41 /* Pthreads condition vars */
  42 #define git_cond pthread_cond_t
  43 #define git_cond_init(c)        pthread_cond_init(c, NULL)
  44 #define git_cond_free(c)        pthread_cond_destroy(c)
  45 #define git_cond_wait(c, l)     pthread_cond_wait(c, l)
  46 #define git_cond_signal(c)      pthread_cond_signal(c)
  47 #define git_cond_broadcast(c)   pthread_cond_broadcast(c)
  48
  49 GIT_INLINE(int) git_atomic_inc(git_atomic *a)
  50 {
  51 #if defined(GIT_WIN32)
  52         return InterlockedIncrement(&a->val);
  53 #elif defined(__GNUC__)
  54         return __sync_add_and_fetch(&a->val, 1);
  55 #else
  56 #       error "Unsupported architecture for atomic operations"
  57 #endif
  58 }
  59
  60 GIT_INLINE(int) git_atomic_dec(git_atomic *a)
  61 {
  62 #if defined(GIT_WIN32)
  63         return InterlockedDecrement(&a->val);
  64 #elif defined(__GNUC__)
  65         return __sync_sub_and_fetch(&a->val, 1);
  66 #else
  67 #       error "Unsupported architecture for atomic operations"
  68 #endif
  69 }
  70
  71 GIT_INLINE(void *) git___compare_and_swap(
  72         volatile void **ptr, void *oldval, void *newval)
  73 {
  74         void *foundval;
  75 #if defined(GIT_WIN32)
  76         foundval = InterlockedCompareExchangePointer(ptr, newval, oldval);
  77 #elif defined(__GNUC__)
  78         foundval = __sync_val_compare_and_swap(ptr, oldval, newval);
  79 #else
  80 #       error "Unsupported architecture for atomic operations"
  81 #endif
  82         return (foundval == oldval) ? oldval : newval;
  83 }
  84
  85 #else
  86
  87 #define git_thread unsigned int
  88 #define git_thread_create(thread, attr, start_routine, arg) (void)0
  89 #define git_thread_kill(thread) (void)0
  90 #define git_thread_exit(status) (void)0
  91 #define git_thread_join(id, status) (void)0
  92
  93 /* Pthreads Mutex */
  94 #define git_mutex unsigned int
  95 #define git_mutex_init(a) (void)0
  96 #define git_mutex_lock(a) 0
  97 #define git_mutex_unlock(a) (void)0
  98 #define git_mutex_free(a) (void)0
  99
 100 /* Pthreads condition vars */
 101 #define git_cond unsigned int
 102 #define git_cond_init(c, a)     (void)0
 103 #define git_cond_free(c) (void)0
 104 #define git_cond_wait(c, l)     (void)0
 105 #define git_cond_signal(c) (void)0
 106 #define git_cond_broadcast(c) (void)0
 107
 108 GIT_INLINE(int) git_atomic_inc(git_atomic *a)
 109 {
 110         return ++a->val;
 111 }
 112
 113 GIT_INLINE(int) git_atomic_dec(git_atomic *a)
 114 {
 115         return --a->val;
 116 }
 117
 118 GIT_INLINE(void *) git___compare_and_swap(
 119         volatile void **ptr, void *oldval, void *newval)
 120 {
 121         if (*ptr == oldval)
 122                 *ptr = newval;
 123         else
 124                 oldval = newval;
 125         return oldval;
 126 }
 127
 128 #endif
 129
 130 /* Atomically replace oldval with newval
 131  * @return oldval if it was replaced or newval if it was not
 132  */
 133 #define git__compare_and_swap(P,O,N) \
 134         git___compare_and_swap((volatile void **)P, O, N)
 135
 136 #define git__swap(ptr, val) git__compare_and_swap(&ptr, ptr, val)
 137
 138 extern int git_online_cpus(void);
 139
 140 #if defined(GIT_THREADS) && defined(GIT_WIN32)
 141 # define GIT_MEMORY_BARRIER MemoryBarrier()
 142 #elif defined(GIT_THREADS)
 143 # define GIT_MEMORY_BARRIER __sync_synchronize()
 144 #else
 145 # define GIT_MEMORY_BARRIER /* noop */
 146 #endif
 147
 148 #endif /* INCLUDE_thread_utils_h__ */