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-rw-r--r-- | linuxthreads/Examples/ex14.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/linuxthreads/Examples/ex14.c b/linuxthreads/Examples/ex14.c new file mode 100644 index 0000000000..4e6e10d9f3 --- /dev/null +++ b/linuxthreads/Examples/ex14.c @@ -0,0 +1,132 @@ +/* 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 = (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 () +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 *) 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" |