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 <common/compat/time.h>
  20 #include <common/time.h>
  21 #include <assert.h>
  22 #include <unistd.h>
  23 #include <stdio.h>
  24 #include <errno.h>
  25
  26 static inline
  27 int64_t elapsed_time_ns(struct timespec *t1, struct timespec *t2)
  28 {
  29         struct timespec delta;
  30
  31         assert(t1 && t2);
  32         delta.tv_sec = t2->tv_sec - t1->tv_sec;
  33         delta.tv_nsec = t2->tv_nsec - t1->tv_nsec;
  34         return ((int64_t) NSEC_PER_SEC * (int64_t) delta.tv_sec) +
  35                         (int64_t) delta.tv_nsec;
  36 }
  37
  38 int usleep_safe(useconds_t usec)
  39 {
  40         int ret = 0;
  41         struct timespec t1, t2;
  42         int64_t time_remaining_ns = (int64_t) usec * (int64_t) NSEC_PER_USEC;
  43
  44         ret = lttng_clock_gettime(CLOCK_MONOTONIC, &t1);
  45         if (ret) {
  46                 ret = -1;
  47                 perror("clock_gettime");
  48                 goto end;
  49         }
  50
  51         while (time_remaining_ns > 0) {
  52                 ret = usleep(time_remaining_ns / (int64_t) NSEC_PER_USEC);
  53                 if (ret && errno != EINTR) {
  54                         perror("usleep");
  55                         goto end;
  56                 }
  57
  58                 ret = clock_gettime(CLOCK_MONOTONIC, &t2);
  59                 if (ret) {
  60                         perror("clock_gettime");
  61                         goto end;
  62                 }
  63
  64                 time_remaining_ns -= elapsed_time_ns(&t1, &t2);
  65         }
  66 end:
  67         return ret;
  68 }