tests/cond_timed.c

   1 #include <assert.h>
   2 #include <pthread.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include <unistd.h>
   7 #include <stdbool.h>
   8 #include <errno.h>
   9 #include <sys/time.h>
  10 #include <libkern/OSAtomic.h>
  11 #include <dispatch/dispatch.h>
  12
  13 struct context {
  14         pthread_cond_t cond;
  15         pthread_mutex_t mutex;
  16         long udelay;
  17         long count;
  18 };
  19
  20 void *wait_thread(void *ptr) {
  21         int res;
  22         struct context *context = ptr;
  23
  24         int i = 0;
  25         char *str;
  26
  27         bool loop = true;
  28         while (loop) {
  29                 struct timespec ts;
  30                 struct timeval tv;
  31                 gettimeofday(&tv, NULL);
  32                 uint64_t ns = tv.tv_usec * NSEC_PER_USEC + context->udelay * NSEC_PER_USEC;
  33                 ts.tv_nsec = ns >= NSEC_PER_SEC ? ns % NSEC_PER_SEC : ns;
  34                 ts.tv_sec = tv.tv_sec + (ns >= NSEC_PER_SEC ? ns / NSEC_PER_SEC : 0);
  35
  36                 res = pthread_mutex_lock(&context->mutex);
  37                 if (res) {
  38                         fprintf(stderr, "[%ld] pthread_mutex_lock: %s\n", context->count, strerror(res));
  39                         abort();
  40                 }
  41
  42                 if (context->count > 0) {
  43                         res = pthread_cond_timedwait(&context->cond, &context->mutex, &ts);
  44                         if (res != ETIMEDOUT) {
  45                                 fprintf(stderr, "[%ld] pthread_cond_timedwait: %s\n", context->count, strerror(res));
  46                                 abort();
  47                         }
  48                         --context->count;
  49                 } else {
  50                         loop = false;
  51                 }
  52
  53                 res = pthread_mutex_unlock(&context->mutex);
  54                 if (res) {
  55                         fprintf(stderr, "[%ld] pthread_mutex_unlock: %s\n", context->count, strerror(res));
  56                         abort();
  57                 }
  58         }
  59
  60         return NULL;
  61 }
  62
  63 int main(int argc, char *argv[])
  64 {
  65         const int threads = 8;
  66         struct context context = {
  67                 .cond = PTHREAD_COND_INITIALIZER,
  68                 .mutex = PTHREAD_MUTEX_INITIALIZER,
  69                 .udelay = 5000,
  70                 .count = 8000,
  71         };
  72         int i;
  73         int res;
  74
  75         uint64_t uexpected = (context.udelay * context.count) / threads;
  76         printf("waittime expected: %llu us\n", uexpected);
  77         struct timeval start, end;
  78         gettimeofday(&start, NULL);
  79
  80         pthread_t p[threads];
  81         for (i = 0; i < threads; ++i) {
  82                 res = pthread_create(&p[i], NULL, wait_thread, &context);
  83                 assert(res == 0);
  84         }
  85
  86         usleep(uexpected);
  87         bool loop = true;
  88         while (loop) {
  89                 res = pthread_mutex_lock(&context.mutex);
  90                 if (res) {
  91                         fprintf(stderr, "[%ld] pthread_mutex_lock: %s\n", context.count, strerror(res));
  92                         abort();
  93                 }
  94                 if (context.count <= 0) {
  95                         loop = false;
  96                 }
  97                 res = pthread_mutex_unlock(&context.mutex);
  98                 if (res) {
  99                         fprintf(stderr, "[%ld] pthread_mutex_unlock: %s\n", context.count, strerror(res));
 100                         abort();
 101                 }
 102         }
 103
 104         for (i = 0; i < threads; ++i) {
 105                 res = pthread_join(p[i], NULL);
 106                 assert(res == 0);
 107         }
 108
 109         gettimeofday(&end, NULL);
 110         uint64_t uelapsed = (end.tv_sec * USEC_PER_SEC + end.tv_usec) -
 111                         (start.tv_sec * USEC_PER_SEC + start.tv_usec);
 112         printf("waittime actual:   %llu us\n", uelapsed);
 113
 114         return 0;
 115 }