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 #if _WIN32_WINNT < _WIN32_WINNT_WIN8 67 68 namespace { 69 70 typedef void(WINAPI *GetSystemTimeAsFileTimePtr)(LPFILETIME); 71 72 class GetSystemTimeInit { 73 public: 74 GetSystemTimeInit() { 75 fp = (GetSystemTimeAsFileTimePtr)GetProcAddress( 76 GetModuleHandleW(L"kernel32.dll"), "GetSystemTimePreciseAsFileTime"); 77 if (fp == nullptr) 78 fp = GetSystemTimeAsFileTime; 79 } 80 GetSystemTimeAsFileTimePtr fp; 81 }; 82 83 GetSystemTimeInit GetSystemTimeAsFileTimeFunc _LIBCPP_INIT_PRIORITY_MAX; 84 } // namespace 85 86 #endif 87 88 static system_clock::time_point __libcpp_system_clock_now() { 89 // FILETIME is in 100ns units 90 using filetime_duration = 91 _VSTD::chrono::duration<__int64, 92 _VSTD::ratio_multiply<_VSTD::ratio<100, 1>, 93 nanoseconds::period>>; 94 95 // The Windows epoch is Jan 1 1601, the Unix epoch Jan 1 1970. 96 static _LIBCPP_CONSTEXPR const seconds nt_to_unix_epoch{11644473600}; 97 98 FILETIME ft; 99 #if (_WIN32_WINNT >= _WIN32_WINNT_WIN8 && WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)) || \ 100 (_WIN32_WINNT >= _WIN32_WINNT_WIN10) 101 GetSystemTimePreciseAsFileTime(&ft); 102 #elif !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) 103 GetSystemTimeAsFileTime(&ft); 104 #else 105 GetSystemTimeAsFileTimeFunc.fp(&ft); 106 #endif 107 108 filetime_duration d{(static_cast<__int64>(ft.dwHighDateTime) << 32) | 109 static_cast<__int64>(ft.dwLowDateTime)}; 110 return system_clock::time_point(duration_cast<system_clock::duration>(d - nt_to_unix_epoch)); 111 } 112 113 #elif defined(CLOCK_REALTIME) && defined(_LIBCPP_USE_CLOCK_GETTIME) 114 115 static system_clock::time_point __libcpp_system_clock_now() { 116 struct timespec tp; 117 if (0 != clock_gettime(CLOCK_REALTIME, &tp)) 118 __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed"); 119 return system_clock::time_point(seconds(tp.tv_sec) + microseconds(tp.tv_nsec / 1000)); 120 } 121 122 #else 123 124 static system_clock::time_point __libcpp_system_clock_now() { 125 timeval tv; 126 gettimeofday(&tv, 0); 127 return system_clock::time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec)); 128 } 129 130 #endif 131 132 const bool system_clock::is_steady; 133 134 system_clock::time_point 135 system_clock::now() noexcept 136 { 137 return __libcpp_system_clock_now(); 138 } 139 140 time_t 141 system_clock::to_time_t(const time_point& t) noexcept 142 { 143 return time_t(duration_cast<seconds>(t.time_since_epoch()).count()); 144 } 145 146 system_clock::time_point 147 system_clock::from_time_t(time_t t) noexcept 148 { 149 return system_clock::time_point(seconds(t)); 150 } 151 152 // 153 // steady_clock 154 // 155 // Warning: If this is not truly steady, then it is non-conforming. It is 156 // better for it to not exist and have the rest of libc++ use system_clock 157 // instead. 158 // 159 160 #ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK 161 162 #if defined(__APPLE__) 163 164 // TODO(ldionne): 165 // This old implementation of steady_clock is retained until Chrome drops supports 166 // for macOS < 10.12. The issue is that they link libc++ statically into their 167 // application, which means that libc++ must support being built for such deployment 168 // targets. See https://llvm.org/D74489 for details. 169 #if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) || \ 170 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 171 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 172 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000) 173 # define _LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME 174 #endif 175 176 #if defined(_LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME) 177 178 // mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of 179 // nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom 180 // are run time constants supplied by the OS. This clock has no relationship 181 // to the Gregorian calendar. It's main use is as a high resolution timer. 182 183 // MachInfo.numer / MachInfo.denom is often 1 on the latest equipment. Specialize 184 // for that case as an optimization. 185 186 static steady_clock::rep steady_simplified() { 187 return static_cast<steady_clock::rep>(mach_absolute_time()); 188 } 189 static double compute_steady_factor() { 190 mach_timebase_info_data_t MachInfo; 191 mach_timebase_info(&MachInfo); 192 return static_cast<double>(MachInfo.numer) / MachInfo.denom; 193 } 194 195 static steady_clock::rep steady_full() { 196 static const double factor = compute_steady_factor(); 197 return static_cast<steady_clock::rep>(mach_absolute_time() * factor); 198 } 199 200 typedef steady_clock::rep (*FP)(); 201 202 static FP init_steady_clock() { 203 mach_timebase_info_data_t MachInfo; 204 mach_timebase_info(&MachInfo); 205 if (MachInfo.numer == MachInfo.denom) 206 return &steady_simplified; 207 return &steady_full; 208 } 209 210 static steady_clock::time_point __libcpp_steady_clock_now() { 211 static FP fp = init_steady_clock(); 212 return steady_clock::time_point(steady_clock::duration(fp())); 213 } 214 215 #else // vvvvv default behavior for Apple platforms vvvvv 216 217 // On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or 218 // mach_absolute_time are able to time functions in the nanosecond range. 219 // Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it 220 // also counts cycles when the system is asleep. Thus, it is the only 221 // acceptable implementation of steady_clock. 222 static steady_clock::time_point __libcpp_steady_clock_now() { 223 struct timespec tp; 224 if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp)) 225 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed"); 226 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 227 } 228 229 #endif 230 231 #elif defined(_LIBCPP_WIN32API) 232 233 // https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says: 234 // If the function fails, the return value is zero. <snip> 235 // On systems that run Windows XP or later, the function will always succeed 236 // and will thus never return zero. 237 238 static LARGE_INTEGER 239 __QueryPerformanceFrequency() 240 { 241 LARGE_INTEGER val; 242 (void) QueryPerformanceFrequency(&val); 243 return val; 244 } 245 246 static steady_clock::time_point __libcpp_steady_clock_now() { 247 static const LARGE_INTEGER freq = __QueryPerformanceFrequency(); 248 249 LARGE_INTEGER counter; 250 (void) QueryPerformanceCounter(&counter); 251 auto seconds = counter.QuadPart / freq.QuadPart; 252 auto fractions = counter.QuadPart % freq.QuadPart; 253 auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart; 254 return steady_clock::time_point(steady_clock::duration(dur)); 255 } 256 257 #elif defined(__MVS__) 258 259 static steady_clock::time_point __libcpp_steady_clock_now() { 260 struct timespec64 ts; 261 if (0 != gettimeofdayMonotonic(&ts)) 262 __throw_system_error(errno, "failed to obtain time of day"); 263 264 return steady_clock::time_point(seconds(ts.tv_sec) + nanoseconds(ts.tv_nsec)); 265 } 266 267 #elif defined(CLOCK_MONOTONIC) 268 269 static steady_clock::time_point __libcpp_steady_clock_now() { 270 struct timespec tp; 271 if (0 != clock_gettime(CLOCK_MONOTONIC, &tp)) 272 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed"); 273 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 274 } 275 276 #else 277 # error "Monotonic clock not implemented on this platform" 278 #endif 279 280 const bool steady_clock::is_steady; 281 282 steady_clock::time_point 283 steady_clock::now() noexcept 284 { 285 return __libcpp_steady_clock_now(); 286 } 287 288 #endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK 289 290 } 291 292 _LIBCPP_END_NAMESPACE_STD 293