src/thread/sem_timedwait.c

   1 #include <semaphore.h>
   2 #include <limits.h>
   3 #include "pthread_impl.h"
   4
   5 static void cleanup(void *p)
   6 {
   7         a_dec(p);
   8 }
   9
  10 int sem_timedwait(sem_t *restrict sem, const struct timespec *restrict at)
  11 {
  12         pthread_testcancel();
  13
  14         if (!sem_trywait(sem)) return 0;
  15
  16         int spins = 100;
  17         while (spins-- && !(sem->__val[0] & SEM_VALUE_MAX) && !sem->__val[1])
  18                 a_spin();
  19
  20         while (sem_trywait(sem)) {
  21                 int r, priv = sem->__val[2];
  22                 a_inc(sem->__val+1);
  23                 a_cas(sem->__val, 0, 0x80000000);
  24                 pthread_cleanup_push(cleanup, (void *)(sem->__val+1));
  25                 r = __timedwait_cp(sem->__val, 0x80000000, CLOCK_REALTIME, at, priv);
  26                 pthread_cleanup_pop(1);
  27                 if (r) {
  28                         errno = r;
  29                         return -1;
  30                 }
  31         }
  32         return 0;
  33 }