tests/utils/utils.c

   1 /*
   2  * Copyright (C) - 2015 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License as published by the
   6  * Free Software Foundation; version 2.1 of the License.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  16  */
  17
  18 #include <stdint.h>
  19 #include <time.h>
  20 #include <assert.h>
  21 #include <unistd.h>
  22 #include <stdio.h>
  23 #include <errno.h>
  24
  25 #define NSEC_PER_SEC 1000000000ULL
  26 #define NSEC_PER_USEC 1000ULL
  27
  28 static inline
  29 int64_t elapsed_time_ns(struct timespec *t1, struct timespec *t2)
  30 {
  31         struct timespec delta;
  32
  33         assert(t1 && t2);
  34         delta.tv_sec = t2->tv_sec - t1->tv_sec;
  35         delta.tv_nsec = t2->tv_nsec - t1->tv_nsec;
  36         return ((int64_t) NSEC_PER_SEC * (int64_t) delta.tv_sec) +
  37                         (int64_t) delta.tv_nsec;
  38 }
  39
  40 int usleep_safe(useconds_t usec)
  41 {
  42         int ret = 0;
  43         struct timespec t1, t2;
  44         int64_t time_remaining_ns = (int64_t) usec * (int64_t) NSEC_PER_USEC;
  45
  46         ret = clock_gettime(CLOCK_MONOTONIC, &t1);
  47         if (ret) {
  48                 ret = -1;
  49                 perror("clock_gettime");
  50                 goto end;
  51         }
  52
  53         while (time_remaining_ns > 0) {
  54                 ret = usleep(time_remaining_ns / (int64_t) NSEC_PER_USEC);
  55                 if (ret && errno != EINTR) {
  56                         perror("usleep");
  57                         goto end;
  58                 }
  59
  60                 ret = clock_gettime(CLOCK_MONOTONIC, &t2);
  61                 if (ret) {
  62                         perror("clock_gettime");
  63                         goto end;
  64                 }
  65
  66                 time_remaining_ns -= elapsed_time_ns(&t1, &t2);
  67         }
  68 end:
  69         return ret;
  70 }