Viewing file:  ex14.c (2.74 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/* Test of POSIX barriers. */
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define NTHREADS 20
#define ROUNDS 20
static pthread_barrier_t barriers[NTHREADS];
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static int counters[NTHREADS];
static int serial[NTHREADS];
static void *
worker (void *arg)
{
void *result = NULL;
int nr = (long int) arg;
int i;
for (i = 0; i < ROUNDS; ++i)
{
int j;
int retval;
if (nr == 0)
{
memset (counters, '\0', sizeof (counters));
memset (serial, '\0', sizeof (serial));
}
retval = pthread_barrier_wait (&barriers[NTHREADS - 1]);
if (retval != 0 && retval != PTHREAD_BARRIER_SERIAL_THREAD)
{
printf ("thread %d failed to wait for all the others\n", nr);
result = (void *) 1;
}
for (j = nr; j < NTHREADS; ++j)
{
/* Increment the counter for this round. */
pthread_mutex_lock (&lock);
++counters[j];
pthread_mutex_unlock (&lock);
/* Wait for the rest. */
retval = pthread_barrier_wait (&barriers[j]);
/* Test the result. */
if (nr == 0 && counters[j] != j + 1)
{
printf ("barrier in round %d released but count is %d\n",
j, counters[j]);
result = (void *) 1;
}
if (retval != 0)
{
if (retval != PTHREAD_BARRIER_SERIAL_THREAD)
{
printf ("thread %d in round %d has nonzero return value != PTHREAD_BARRIER_SERIAL_THREAD\n",
nr, j);
result = (void *) 1;
}
else
{
pthread_mutex_lock (&lock);
++serial[j];
pthread_mutex_unlock (&lock);
}
}
/* Wait for the rest again. */
retval = pthread_barrier_wait (&barriers[j]);
/* Now we can check whether exactly one thread was serializing. */
if (nr == 0 && serial[j] != 1)
{
printf ("not exactly one serial thread in round %d\n", j);
result = (void *) 1;
}
}
}
return result;
}
#define TEST_FUNCTION do_test ()
#define TIMEOUT 60
static int
do_test (void)
{
pthread_t threads[NTHREADS];
int i;
void *res;
int result = 0;
/* Initialized the barrier variables. */
for (i = 0; i < NTHREADS; ++i)
if (pthread_barrier_init (&barriers[i], NULL, i + 1) != 0)
{
printf ("Failed to initialize barrier %d\n", i);
exit (1);
}
/* Start the threads. */
for (i = 0; i < NTHREADS; ++i)
if (pthread_create (&threads[i], NULL, worker, (void *) (long int) i) != 0)
{
printf ("Failed to start thread %d\n", i);
exit (1);
}
/* And wait for them. */
for (i = 0; i < NTHREADS; ++i)
if (pthread_join (threads[i], &res) != 0 || res != NULL)
{
printf ("thread %d returned a failure\n", i);
result = 1;
}
if (result == 0)
puts ("all OK");
return result;
}
#include "../test-skeleton.c"
|