src/thread-utils.h

   1 #ifndef INCLUDE_thread_utils_h__
   2 #define INCLUDE_thread_utils_h__
   3
   4 #if defined(GIT_HAS_PTHREAD)
   5 typedef pthread_mutex_t git_lck;
   6 # define GITLCK_INIT      PTHREAD_MUTEX_INITIALIZER
   7 # define gitlck_init(a)   pthread_mutex_init(a, NULL)
   8 # define gitlck_lock(a)   pthread_mutex_lock(a)
   9 # define gitlck_unlock(a) pthread_mutex_unlock(a)
  10 # define gitlck_free(a)   pthread_mutex_destroy(a)
  11
  12 # if defined(GIT_HAS_ASM_ATOMIC)
  13 #  include <asm/atomic.h>
  14 typedef atomic_t git_refcnt;
  15 #  define gitrc_init(a)   atomic_set(a, 0)
  16 #  define gitrc_inc(a)    atomic_inc_return(a)
  17 #  define gitrc_dec(a)    atomic_dec_and_test(a)
  18 #  define gitrc_free(a)   (void)0
  19
  20 # else
  21 typedef struct { git_lck lock; int counter; } git_refcnt;
  22
  23 /** Initialize to 0.  No memory barrier is issued. */
  24 GIT_INLINE(void) gitrc_init(git_refcnt *p)
  25 {
  26         gitlck_init(&p->lock);
  27         p->counter = 0;
  28 }
  29
  30 /**
  31  * Increment.
  32  *
  33  * Atomically increments @p by 1.  A memory barrier is also
  34  * issued before and after the operation.
  35  *
  36  * @param p pointer of type git_refcnt
  37  */
  38 GIT_INLINE(void) gitrc_inc(git_refcnt *p)
  39 {
  40         gitlck_lock(&p->lock);
  41         p->counter++;
  42         gitlck_unlock(&p->lock);
  43 }
  44
  45 /**
  46  * Decrement and test.
  47  *
  48  * Atomically decrements @p by 1 and returns true if the
  49  * result is 0, or false for all other cases.  A memory
  50  * barrier is also issued before and after the operation.
  51  *
  52  * @param p pointer of type git_refcnt
  53  */
  54 GIT_INLINE(int) gitrc_dec(git_refcnt *p)
  55 {
  56         int c;
  57         gitlck_lock(&p->lock);
  58         c = --p->counter;
  59         gitlck_unlock(&p->lock);
  60         return !c;
  61 }
  62
  63 /** Free any resources associated with the counter. */
  64 #  define gitrc_free(p) gitlck_free(&(p)->lock)
  65
  66 # endif
  67
  68 #elif defined(GIT_THREADS)
  69 # error GIT_THREADS but no git_lck implementation
  70
  71 #else
  72 typedef struct { int dummy; } git_lck;
  73 # define GIT_MUTEX_INIT   {}
  74 # define gitlck_init(a)   (void)0
  75 # define gitlck_lock(a)   (void)0
  76 # define gitlck_unlock(a) (void)0
  77 # define gitlck_free(a)   (void)0
  78
  79 typedef struct { int counter; } git_refcnt;
  80 # define gitrc_init(a)   ((a)->counter = 0)
  81 # define gitrc_inc(a)    ((a)->counter++)
  82 # define gitrc_dec(a)    (--(a)->counter == 0)
  83 # define gitrc_free(a)   (void)0
  84
  85 #endif
  86
  87 GIT_EXTERN(int) git_online_cpus(void);
  88
  89 #endif /* INCLUDE_thread_utils_h__ */