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-rw-r--r--linuxthreads/Examples/ex14.c133
1 files changed, 133 insertions, 0 deletions
diff --git a/linuxthreads/Examples/ex14.c b/linuxthreads/Examples/ex14.c
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+++ b/linuxthreads/Examples/ex14.c
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+/* 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"