1 //===------------------------- chrono.cpp ---------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #if defined(__MVS__) 10 // As part of monotonic clock support on z/OS we need macro _LARGE_TIME_API 11 // to be defined before any system header to include definition of struct timespec64. 12 #define _LARGE_TIME_API 13 #endif 14 15 #include "chrono" 16 #include "cerrno" // errno 17 #include "system_error" // __throw_system_error 18 19 #if defined(__MVS__) 20 #include <__support/ibm/gettod_zos.h> // gettimeofdayMonotonic 21 #endif 22 23 #include <time.h> // clock_gettime and CLOCK_{MONOTONIC,REALTIME,MONOTONIC_RAW} 24 #include "include/apple_availability.h" 25 26 #if __has_include(<unistd.h>) 27 # include <unistd.h> 28 #endif 29 30 #if __has_include(<sys/time.h>) 31 # include <sys/time.h> // for gettimeofday and timeval 32 #endif 33 34 #if !defined(__APPLE__) && defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0 35 # define _LIBCPP_USE_CLOCK_GETTIME 36 #endif 37 38 #if defined(_LIBCPP_WIN32API) 39 # define WIN32_LEAN_AND_MEAN 40 # define VC_EXTRA_LEAN 41 # include <windows.h> 42 # if _WIN32_WINNT >= _WIN32_WINNT_WIN8 43 # include <winapifamily.h> 44 # endif 45 #endif // defined(_LIBCPP_WIN32API) 46 47 #if __has_include(<mach/mach_time.h>) 48 # include <mach/mach_time.h> 49 #endif 50 51 #if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB) 52 # pragma comment(lib, "rt") 53 #endif 54 55 _LIBCPP_BEGIN_NAMESPACE_STD 56 57 namespace chrono 58 { 59 60 // 61 // system_clock 62 // 63 64 #if defined(_LIBCPP_WIN32API) 65 66 static system_clock::time_point __libcpp_system_clock_now() { 67 // FILETIME is in 100ns units 68 using filetime_duration = 69 _VSTD::chrono::duration<__int64, 70 _VSTD::ratio_multiply<_VSTD::ratio<100, 1>, 71 nanoseconds::period>>; 72 73 // The Windows epoch is Jan 1 1601, the Unix epoch Jan 1 1970. 74 static _LIBCPP_CONSTEXPR const seconds nt_to_unix_epoch{11644473600}; 75 76 FILETIME ft; 77 #if _WIN32_WINNT >= _WIN32_WINNT_WIN8 && WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) 78 GetSystemTimePreciseAsFileTime(&ft); 79 #else 80 GetSystemTimeAsFileTime(&ft); 81 #endif 82 83 filetime_duration d{(static_cast<__int64>(ft.dwHighDateTime) << 32) | 84 static_cast<__int64>(ft.dwLowDateTime)}; 85 return system_clock::time_point(duration_cast<system_clock::duration>(d - nt_to_unix_epoch)); 86 } 87 88 #elif defined(CLOCK_REALTIME) && defined(_LIBCPP_USE_CLOCK_GETTIME) 89 90 static system_clock::time_point __libcpp_system_clock_now() { 91 struct timespec tp; 92 if (0 != clock_gettime(CLOCK_REALTIME, &tp)) 93 __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed"); 94 return system_clock::time_point(seconds(tp.tv_sec) + microseconds(tp.tv_nsec / 1000)); 95 } 96 97 #else 98 99 static system_clock::time_point __libcpp_system_clock_now() { 100 timeval tv; 101 gettimeofday(&tv, 0); 102 return system_clock::time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec)); 103 } 104 105 #endif 106 107 const bool system_clock::is_steady; 108 109 system_clock::time_point 110 system_clock::now() noexcept 111 { 112 return __libcpp_system_clock_now(); 113 } 114 115 time_t 116 system_clock::to_time_t(const time_point& t) noexcept 117 { 118 return time_t(duration_cast<seconds>(t.time_since_epoch()).count()); 119 } 120 121 system_clock::time_point 122 system_clock::from_time_t(time_t t) noexcept 123 { 124 return system_clock::time_point(seconds(t)); 125 } 126 127 // 128 // steady_clock 129 // 130 // Warning: If this is not truly steady, then it is non-conforming. It is 131 // better for it to not exist and have the rest of libc++ use system_clock 132 // instead. 133 // 134 135 #ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK 136 137 #if defined(__APPLE__) 138 139 // TODO(ldionne): 140 // This old implementation of steady_clock is retained until Chrome drops supports 141 // for macOS < 10.12. The issue is that they link libc++ statically into their 142 // application, which means that libc++ must support being built for such deployment 143 // targets. See https://llvm.org/D74489 for details. 144 #if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) || \ 145 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 146 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 147 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000) 148 # define _LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME 149 #endif 150 151 #if defined(_LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME) 152 153 // mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of 154 // nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom 155 // are run time constants supplied by the OS. This clock has no relationship 156 // to the Gregorian calendar. It's main use is as a high resolution timer. 157 158 // MachInfo.numer / MachInfo.denom is often 1 on the latest equipment. Specialize 159 // for that case as an optimization. 160 161 static steady_clock::rep steady_simplified() { 162 return static_cast<steady_clock::rep>(mach_absolute_time()); 163 } 164 static double compute_steady_factor() { 165 mach_timebase_info_data_t MachInfo; 166 mach_timebase_info(&MachInfo); 167 return static_cast<double>(MachInfo.numer) / MachInfo.denom; 168 } 169 170 static steady_clock::rep steady_full() { 171 static const double factor = compute_steady_factor(); 172 return static_cast<steady_clock::rep>(mach_absolute_time() * factor); 173 } 174 175 typedef steady_clock::rep (*FP)(); 176 177 static FP init_steady_clock() { 178 mach_timebase_info_data_t MachInfo; 179 mach_timebase_info(&MachInfo); 180 if (MachInfo.numer == MachInfo.denom) 181 return &steady_simplified; 182 return &steady_full; 183 } 184 185 static steady_clock::time_point __libcpp_steady_clock_now() { 186 static FP fp = init_steady_clock(); 187 return steady_clock::time_point(steady_clock::duration(fp())); 188 } 189 190 #else // vvvvv default behavior for Apple platforms vvvvv 191 192 // On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or 193 // mach_absolute_time are able to time functions in the nanosecond range. 194 // Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it 195 // also counts cycles when the system is asleep. Thus, it is the only 196 // acceptable implementation of steady_clock. 197 static steady_clock::time_point __libcpp_steady_clock_now() { 198 struct timespec tp; 199 if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp)) 200 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed"); 201 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 202 } 203 204 #endif 205 206 #elif defined(_LIBCPP_WIN32API) 207 208 // https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says: 209 // If the function fails, the return value is zero. <snip> 210 // On systems that run Windows XP or later, the function will always succeed 211 // and will thus never return zero. 212 213 static LARGE_INTEGER 214 __QueryPerformanceFrequency() 215 { 216 LARGE_INTEGER val; 217 (void) QueryPerformanceFrequency(&val); 218 return val; 219 } 220 221 static steady_clock::time_point __libcpp_steady_clock_now() { 222 static const LARGE_INTEGER freq = __QueryPerformanceFrequency(); 223 224 LARGE_INTEGER counter; 225 (void) QueryPerformanceCounter(&counter); 226 auto seconds = counter.QuadPart / freq.QuadPart; 227 auto fractions = counter.QuadPart % freq.QuadPart; 228 auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart; 229 return steady_clock::time_point(steady_clock::duration(dur)); 230 } 231 232 #elif defined(__MVS__) 233 234 static steady_clock::time_point __libcpp_steady_clock_now() { 235 struct timespec64 ts; 236 if (0 != gettimeofdayMonotonic(&ts)) 237 __throw_system_error(errno, "failed to obtain time of day"); 238 239 return steady_clock::time_point(seconds(ts.tv_sec) + nanoseconds(ts.tv_nsec)); 240 } 241 242 #elif defined(CLOCK_MONOTONIC) 243 244 static steady_clock::time_point __libcpp_steady_clock_now() { 245 struct timespec tp; 246 if (0 != clock_gettime(CLOCK_MONOTONIC, &tp)) 247 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed"); 248 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 249 } 250 251 #else 252 # error "Monotonic clock not implemented on this platform" 253 #endif 254 255 const bool steady_clock::is_steady; 256 257 steady_clock::time_point 258 steady_clock::now() noexcept 259 { 260 return __libcpp_steady_clock_now(); 261 } 262 263 #endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK 264 265 } 266 267 _LIBCPP_END_NAMESPACE_STD 268