OpenMP-Examples/sources/Example_simple_lock.1.c

/*
* @@name:	simple_lock.1c
* @@type:	C
* @@compilable:	yes
* @@linkable:	yes
* @@expect:	success
*/
#include <stdio.h>
#include <omp.h>
void skip(int i) {}
void work(int i) {}
int main()
{
  omp_lock_t lck;
  int id;
  omp_init_lock(&lck);

  #pragma omp parallel shared(lck) private(id)
  {
    id = omp_get_thread_num();

    omp_set_lock(&lck);
    /*  only one thread at a time can execute this printf */
    printf("My thread id is %d.\n", id);
    omp_unset_lock(&lck);

    while (! omp_test_lock(&lck)) {
      skip(id);   /* we do not yet have the lock,
                     so we must do something else */
    }

    work(id);      /* we now have the lock
                      and can do the work */

    omp_unset_lock(&lck);
  }
  omp_destroy_lock(&lck);

  return 0;
}