libc-top-half/musl/src/thread/sem_timedwait.c

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