src/shims/time.h

   1 /*
   2  * Copyright (c) 2008-2013 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_APACHE_LICENSE_HEADER_START@
   5  *
   6  * Licensed under the Apache License, Version 2.0 (the "License");
   7  * you may not use this file except in compliance with the License.
   8  * You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  *
  18  * @APPLE_APACHE_LICENSE_HEADER_END@
  19  */
  20
  21 /*
  22  * IMPORTANT: This header file describes INTERNAL interfaces to libdispatch
  23  * which are subject to change in future releases of Mac OS X. Any applications
  24  * relying on these interfaces WILL break.
  25  */
  26
  27 #ifndef __DISPATCH_SHIMS_TIME__
  28 #define __DISPATCH_SHIMS_TIME__
  29
  30 #ifndef __DISPATCH_INDIRECT__
  31 #error "Please #include <dispatch/dispatch.h> instead of this file directly."
  32 #endif
  33
  34 #if TARGET_OS_WIN32
  35 static inline unsigned int
  36 sleep(unsigned int seconds)
  37 {
  38         Sleep(seconds * 1000); // milliseconds
  39         return 0;
  40 }
  41 #endif
  42
  43 typedef enum {
  44         DISPATCH_CLOCK_WALL,
  45         DISPATCH_CLOCK_MACH,
  46 #define DISPATCH_CLOCK_COUNT  (DISPATCH_CLOCK_MACH + 1)
  47 } dispatch_clock_t;
  48
  49 void _dispatch_time_init(void);
  50
  51 #if defined(__i386__) || defined(__x86_64__) || !HAVE_MACH_ABSOLUTE_TIME
  52 #define DISPATCH_TIME_UNIT_USES_NANOSECONDS 1
  53 #else
  54 #define DISPATCH_TIME_UNIT_USES_NANOSECONDS 0
  55 #endif
  56
  57 #if DISPATCH_TIME_UNIT_USES_NANOSECONDS
  58 // x86 currently implements mach time in nanoseconds
  59 // this is NOT likely to change
  60 DISPATCH_ALWAYS_INLINE
  61 static inline uint64_t
  62 _dispatch_time_mach2nano(uint64_t machtime)
  63 {
  64         return machtime;
  65 }
  66
  67 DISPATCH_ALWAYS_INLINE
  68 static inline uint64_t
  69 _dispatch_time_nano2mach(uint64_t nsec)
  70 {
  71         return nsec;
  72 }
  73 #else
  74 #define DISPATCH_USE_HOST_TIME 1
  75 extern uint64_t (*_dispatch_host_time_mach2nano)(uint64_t machtime);
  76 extern uint64_t (*_dispatch_host_time_nano2mach)(uint64_t nsec);
  77 static inline uint64_t
  78 _dispatch_time_mach2nano(uint64_t machtime)
  79 {
  80         return _dispatch_host_time_mach2nano(machtime);
  81 }
  82
  83 static inline uint64_t
  84 _dispatch_time_nano2mach(uint64_t nsec)
  85 {
  86         return _dispatch_host_time_nano2mach(nsec);
  87 }
  88 #endif // DISPATCH_USE_HOST_TIME
  89
  90 /* XXXRW: Some kind of overflow detection needed? */
  91 #define _dispatch_timespec_to_nano(ts) \
  92                 ((uint64_t)(ts).tv_sec * NSEC_PER_SEC + (uint64_t)(ts).tv_nsec)
  93 #define _dispatch_timeval_to_nano(tv) \
  94                 ((uint64_t)(tv).tv_sec * NSEC_PER_SEC + \
  95                                 (uint64_t)(tv).tv_usec * NSEC_PER_USEC)
  96
  97 static inline uint64_t
  98 _dispatch_get_nanoseconds(void)
  99 {
 100         dispatch_static_assert(sizeof(NSEC_PER_SEC) == 8);
 101         dispatch_static_assert(sizeof(USEC_PER_SEC) == 8);
 102
 103 #if TARGET_OS_MAC
 104         return clock_gettime_nsec_np(CLOCK_REALTIME);
 105 #elif HAVE_DECL_CLOCK_REALTIME
 106         struct timespec ts;
 107         dispatch_assume_zero(clock_gettime(CLOCK_REALTIME, &ts));
 108         return _dispatch_timespec_to_nano(ts);
 109 #elif TARGET_OS_WIN32
 110         // FILETIME is 100-nanosecond intervals since January 1, 1601 (UTC).
 111         FILETIME ft;
 112         ULARGE_INTEGER li;
 113         GetSystemTimeAsFileTime(&ft);
 114         li.LowPart = ft.dwLowDateTime;
 115         li.HighPart = ft.dwHighDateTime;
 116         return li.QuadPart * 100ull;
 117 #else
 118         struct timeval tv;
 119         dispatch_assert_zero(gettimeofday(&tv, NULL));
 120         return _dispatch_timeval_to_nano(tv);
 121 #endif
 122 }
 123
 124 static inline uint64_t
 125 _dispatch_absolute_time(void)
 126 {
 127 #if HAVE_MACH_ABSOLUTE_TIME
 128         return mach_absolute_time();
 129 #elif HAVE_DECL_CLOCK_UPTIME && !defined(__linux__)
 130         struct timespec ts;
 131         dispatch_assume_zero(clock_gettime(CLOCK_UPTIME, &ts));
 132         return _dispatch_timespec_to_nano(ts);
 133 #elif HAVE_DECL_CLOCK_MONOTONIC
 134         struct timespec ts;
 135         dispatch_assume_zero(clock_gettime(CLOCK_MONOTONIC, &ts));
 136         return _dispatch_timespec_to_nano(ts);
 137 #elif TARGET_OS_WIN32
 138         LARGE_INTEGER now;
 139         return QueryPerformanceCounter(&now) ? now.QuadPart : 0;
 140 #else
 141 #error platform needs to implement _dispatch_absolute_time()
 142 #endif
 143 }
 144
 145 DISPATCH_ALWAYS_INLINE
 146 static inline uint64_t
 147 _dispatch_approximate_time(void)
 148 {
 149 #if HAVE_MACH_APPROXIMATE_TIME
 150         return mach_approximate_time();
 151 #elif HAVE_DECL_CLOCK_UPTIME_FAST && !defined(__linux__)
 152         struct timespec ts;
 153         dispatch_assume_zero(clock_gettime(CLOCK_UPTIME_FAST, &ts));
 154         return _dispatch_timespec_to_nano(ts);
 155 #elif defined(__linux__)
 156         struct timespec ts;
 157         dispatch_assume_zero(clock_gettime(CLOCK_REALTIME_COARSE, &ts));
 158         return _dispatch_timespec_to_nano(ts);
 159 #else
 160         return _dispatch_absolute_time();
 161 #endif
 162 }
 163
 164 DISPATCH_ALWAYS_INLINE
 165 static inline uint64_t
 166 _dispatch_time_now(dispatch_clock_t clock)
 167 {
 168         switch (clock) {
 169         case DISPATCH_CLOCK_MACH:
 170                 return _dispatch_absolute_time();
 171         case DISPATCH_CLOCK_WALL:
 172                 return _dispatch_get_nanoseconds();
 173         }
 174         __builtin_unreachable();
 175 }
 176
 177 typedef struct {
 178         uint64_t nows[DISPATCH_CLOCK_COUNT];
 179 } dispatch_clock_now_cache_s, *dispatch_clock_now_cache_t;
 180
 181 DISPATCH_ALWAYS_INLINE
 182 static inline uint64_t
 183 _dispatch_time_now_cached(dispatch_clock_t clock,
 184                 dispatch_clock_now_cache_t cache)
 185 {
 186         if (likely(cache->nows[clock])) {
 187                 return cache->nows[clock];
 188         }
 189         return cache->nows[clock] = _dispatch_time_now(clock);
 190 }
 191
 192 #endif // __DISPATCH_SHIMS_TIME__