gen/clock_gettime.c

   1 /*
   2  * Copyright (c) 2016 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <errno.h>
  25 #include <stdatomic.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <stdint.h>
  29 #include <string.h>
  30 #include <time.h>
  31 #include <unistd.h>
  32 #include <sys/time.h>
  33 #include <sys/types.h>
  34 #include <sys/sysctl.h>
  35 #include <mach/mach_error.h>
  36 #include <mach/mach_time.h>
  37 #include <os/base_private.h>
  38
  39 extern uint64_t __thread_selfusage(void);
  40
  41 #define timeval2nsec(tv) (tv.tv_sec * NSEC_PER_SEC + tv.tv_usec * NSEC_PER_USEC)
  42
  43 static uint64_t
  44 _boottime_fallback_usec(void)
  45 {
  46     struct timeval tv;
  47     size_t len = sizeof(tv);
  48     int ret = sysctlbyname("kern.boottime", &tv, &len, NULL, 0);
  49     if (ret == -1) return 0;
  50     return (uint64_t)tv.tv_sec * USEC_PER_SEC + (uint64_t)tv.tv_usec;
  51 }
  52
  53 static int
  54 _mach_boottime_usec(uint64_t *boottime, struct timeval *realtime)
  55 {
  56     uint64_t bt1 = 0, bt2 = 0;
  57     int ret;
  58     do {
  59         bt1 = mach_boottime_usec();
  60         if (os_slowpath(bt1 == 0)) bt1 = _boottime_fallback_usec();
  61
  62         atomic_thread_fence(memory_order_seq_cst);
  63
  64         ret = gettimeofday(realtime, NULL);
  65         if (ret != 0) return ret;
  66
  67         atomic_thread_fence(memory_order_seq_cst);
  68
  69         bt2 = mach_boottime_usec();
  70         if (os_slowpath(bt2 == 0)) bt2 = _boottime_fallback_usec();
  71     } while (os_slowpath(bt1 != bt2));
  72     *boottime = bt1;
  73     return 0;
  74 }
  75
  76 uint64_t
  77 clock_gettime_nsec_np(clockid_t clock_id)
  78 {
  79     switch(clock_id){
  80     case CLOCK_REALTIME: {
  81         struct timeval tv;
  82         int ret = gettimeofday(&tv, NULL);
  83         if (ret) return 0;
  84         return timeval2nsec(tv);
  85     }
  86     case CLOCK_MONOTONIC: {
  87         struct timeval tv;
  88         uint64_t boottime;
  89         int ret = _mach_boottime_usec(&boottime, &tv);
  90         if (ret) return 0;
  91         boottime *= NSEC_PER_USEC;
  92         return timeval2nsec(tv) - boottime;
  93     }
  94     case CLOCK_PROCESS_CPUTIME_ID: {
  95         struct rusage ru;
  96         int ret = getrusage(RUSAGE_SELF, &ru);
  97         if (ret) return 0;
  98         return timeval2nsec(ru.ru_utime) + timeval2nsec(ru.ru_stime);
  99     }
 100     default:
 101         // calls that use mach_absolute_time units fall through into a common path
 102         break;
 103     }
 104
 105     // Mach Absolute Time unit-based calls
 106     mach_timebase_info_data_t tb_info;
 107     if (mach_timebase_info(&tb_info)) return 0;
 108     uint64_t mach_time;
 109
 110     switch(clock_id){
 111     case CLOCK_MONOTONIC_RAW:
 112         mach_time = mach_continuous_time();
 113         break;
 114     case CLOCK_MONOTONIC_RAW_APPROX:
 115         mach_time = mach_continuous_approximate_time();
 116         break;
 117     case CLOCK_UPTIME_RAW:
 118         mach_time = mach_absolute_time();
 119         break;
 120     case CLOCK_UPTIME_RAW_APPROX:
 121         mach_time = mach_approximate_time();
 122         break;
 123     case CLOCK_THREAD_CPUTIME_ID:
 124         mach_time = __thread_selfusage();
 125         break;
 126     default:
 127         errno = EINVAL;
 128         return 0;
 129     }
 130
 131     return (mach_time * tb_info.numer) / tb_info.denom;
 132 }
 133
 134 int
 135 clock_gettime(clockid_t clk_id, struct timespec *tp)
 136 {
 137     switch(clk_id){
 138     case CLOCK_REALTIME: {
 139         struct timeval tv;
 140         int ret = gettimeofday(&tv, NULL);
 141         TIMEVAL_TO_TIMESPEC(&tv, tp);
 142         return ret;
 143     }
 144     case CLOCK_MONOTONIC: {
 145         struct timeval tv;
 146         uint64_t boottime_usec;
 147         int ret = _mach_boottime_usec(&boottime_usec, &tv);
 148         struct timeval boottime = {
 149             .tv_sec = boottime_usec / USEC_PER_SEC,
 150             .tv_usec = boottime_usec % USEC_PER_SEC
 151         };
 152         timersub(&tv, &boottime, &tv);
 153         TIMEVAL_TO_TIMESPEC(&tv, tp);
 154         return ret;
 155     }
 156     case CLOCK_PROCESS_CPUTIME_ID: {
 157         struct rusage ru;
 158         int ret = getrusage(RUSAGE_SELF, &ru);
 159         timeradd(&ru.ru_utime, &ru.ru_stime, &ru.ru_utime);
 160         TIMEVAL_TO_TIMESPEC(&ru.ru_utime, tp);
 161         return ret;
 162     }
 163     case CLOCK_MONOTONIC_RAW:
 164     case CLOCK_MONOTONIC_RAW_APPROX:
 165     case CLOCK_UPTIME_RAW:
 166     case CLOCK_UPTIME_RAW_APPROX:
 167     case CLOCK_THREAD_CPUTIME_ID: {
 168         uint64_t ns = clock_gettime_nsec_np(clk_id);
 169         if (!ns) return -1;
 170
 171         tp->tv_sec = ns/NSEC_PER_SEC;
 172         tp->tv_nsec = ns % NSEC_PER_SEC;
 173         return 0;
 174     }
 175     default:
 176         errno = EINVAL;
 177         return -1;
 178     }
 179 }
 180
 181 int
 182 clock_getres(clockid_t clk_id, struct timespec *res)
 183 {
 184     switch(clk_id){
 185     case CLOCK_REALTIME:
 186     case CLOCK_MONOTONIC:
 187     case CLOCK_PROCESS_CPUTIME_ID:
 188         res->tv_nsec = NSEC_PER_USEC;
 189         res->tv_sec = 0;
 190         return 0;
 191
 192     case CLOCK_MONOTONIC_RAW:
 193     case CLOCK_MONOTONIC_RAW_APPROX:
 194     case CLOCK_UPTIME_RAW:
 195     case CLOCK_UPTIME_RAW_APPROX:
 196     case CLOCK_THREAD_CPUTIME_ID: {
 197         mach_timebase_info_data_t tb_info;
 198         if (mach_timebase_info(&tb_info)){
 199             return -1;
 200         }
 201         res->tv_nsec = tb_info.numer / tb_info.denom + (tb_info.numer % tb_info.denom != 0);
 202         res->tv_sec = 0;
 203         return 0;
 204     }
 205
 206     default:
 207         errno = EINVAL;
 208         return -1;
 209     }
 210 }
 211
 212 int
 213 clock_settime(clockid_t clk_id, const struct timespec *tp)
 214 {
 215     switch(clk_id){
 216     case CLOCK_REALTIME: {
 217         struct timeval tv;
 218         TIMESPEC_TO_TIMEVAL(&tv,tp)
 219         return settimeofday(&tv, NULL);
 220     }
 221     default:
 222         errno = EINVAL;
 223         return -1;
 224     }
 225 }