1 //===----------------------------------------------------------------------===// 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 defined(__Fuchsia__) 48 # include <zircon/syscalls.h> 49 #endif 50 51 #if __has_include(<mach/mach_time.h>) 52 # include <mach/mach_time.h> 53 #endif 54 55 #if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB) 56 # pragma comment(lib, "rt") 57 #endif 58 59 _LIBCPP_BEGIN_NAMESPACE_STD 60 61 namespace chrono 62 { 63 64 // 65 // system_clock 66 // 67 68 #if defined(_LIBCPP_WIN32API) 69 70 #if _WIN32_WINNT < _WIN32_WINNT_WIN8 71 72 namespace { 73 74 typedef void(WINAPI *GetSystemTimeAsFileTimePtr)(LPFILETIME); 75 76 class GetSystemTimeInit { 77 public: 78 GetSystemTimeInit() { 79 fp = (GetSystemTimeAsFileTimePtr)GetProcAddress( 80 GetModuleHandleW(L"kernel32.dll"), "GetSystemTimePreciseAsFileTime"); 81 if (fp == nullptr) 82 fp = GetSystemTimeAsFileTime; 83 } 84 GetSystemTimeAsFileTimePtr fp; 85 }; 86 87 // Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority 88 // attribute with a value that's reserved for the implementation (we're the implementation). 89 #include "chrono_system_time_init.h" 90 } // namespace 91 92 #endif 93 94 static system_clock::time_point __libcpp_system_clock_now() { 95 // FILETIME is in 100ns units 96 using filetime_duration = 97 _VSTD::chrono::duration<__int64, 98 _VSTD::ratio_multiply<_VSTD::ratio<100, 1>, 99 nanoseconds::period>>; 100 101 // The Windows epoch is Jan 1 1601, the Unix epoch Jan 1 1970. 102 static _LIBCPP_CONSTEXPR const seconds nt_to_unix_epoch{11644473600}; 103 104 FILETIME ft; 105 #if (_WIN32_WINNT >= _WIN32_WINNT_WIN8 && WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)) || \ 106 (_WIN32_WINNT >= _WIN32_WINNT_WIN10) 107 GetSystemTimePreciseAsFileTime(&ft); 108 #elif !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) 109 GetSystemTimeAsFileTime(&ft); 110 #else 111 GetSystemTimeAsFileTimeFunc.fp(&ft); 112 #endif 113 114 filetime_duration d{(static_cast<__int64>(ft.dwHighDateTime) << 32) | 115 static_cast<__int64>(ft.dwLowDateTime)}; 116 return system_clock::time_point(duration_cast<system_clock::duration>(d - nt_to_unix_epoch)); 117 } 118 119 #elif defined(CLOCK_REALTIME) && defined(_LIBCPP_USE_CLOCK_GETTIME) 120 121 static system_clock::time_point __libcpp_system_clock_now() { 122 struct timespec tp; 123 if (0 != clock_gettime(CLOCK_REALTIME, &tp)) 124 __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed"); 125 return system_clock::time_point(seconds(tp.tv_sec) + microseconds(tp.tv_nsec / 1000)); 126 } 127 128 #else 129 130 static system_clock::time_point __libcpp_system_clock_now() { 131 timeval tv; 132 gettimeofday(&tv, 0); 133 return system_clock::time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec)); 134 } 135 136 #endif 137 138 const bool system_clock::is_steady; 139 140 system_clock::time_point 141 system_clock::now() noexcept 142 { 143 return __libcpp_system_clock_now(); 144 } 145 146 time_t 147 system_clock::to_time_t(const time_point& t) noexcept 148 { 149 return time_t(duration_cast<seconds>(t.time_since_epoch()).count()); 150 } 151 152 system_clock::time_point 153 system_clock::from_time_t(time_t t) noexcept 154 { 155 return system_clock::time_point(seconds(t)); 156 } 157 158 // 159 // steady_clock 160 // 161 // Warning: If this is not truly steady, then it is non-conforming. It is 162 // better for it to not exist and have the rest of libc++ use system_clock 163 // instead. 164 // 165 166 #ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK 167 168 #if defined(__APPLE__) 169 170 // TODO(ldionne): 171 // This old implementation of steady_clock is retained until Chrome drops supports 172 // for macOS < 10.12. The issue is that they link libc++ statically into their 173 // application, which means that libc++ must support being built for such deployment 174 // targets. See https://llvm.org/D74489 for details. 175 #if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) || \ 176 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 177 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) || \ 178 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000) 179 # define _LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME 180 #endif 181 182 #if defined(_LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME) 183 184 // mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of 185 // nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom 186 // are run time constants supplied by the OS. This clock has no relationship 187 // to the Gregorian calendar. It's main use is as a high resolution timer. 188 189 // MachInfo.numer / MachInfo.denom is often 1 on the latest equipment. Specialize 190 // for that case as an optimization. 191 192 static steady_clock::rep steady_simplified() { 193 return static_cast<steady_clock::rep>(mach_absolute_time()); 194 } 195 static double compute_steady_factor() { 196 mach_timebase_info_data_t MachInfo; 197 mach_timebase_info(&MachInfo); 198 return static_cast<double>(MachInfo.numer) / MachInfo.denom; 199 } 200 201 static steady_clock::rep steady_full() { 202 static const double factor = compute_steady_factor(); 203 return static_cast<steady_clock::rep>(mach_absolute_time() * factor); 204 } 205 206 typedef steady_clock::rep (*FP)(); 207 208 static FP init_steady_clock() { 209 mach_timebase_info_data_t MachInfo; 210 mach_timebase_info(&MachInfo); 211 if (MachInfo.numer == MachInfo.denom) 212 return &steady_simplified; 213 return &steady_full; 214 } 215 216 static steady_clock::time_point __libcpp_steady_clock_now() { 217 static FP fp = init_steady_clock(); 218 return steady_clock::time_point(steady_clock::duration(fp())); 219 } 220 221 #else // vvvvv default behavior for Apple platforms vvvvv 222 223 // On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or 224 // mach_absolute_time are able to time functions in the nanosecond range. 225 // Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it 226 // also counts cycles when the system is asleep. Thus, it is the only 227 // acceptable implementation of steady_clock. 228 static steady_clock::time_point __libcpp_steady_clock_now() { 229 struct timespec tp; 230 if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp)) 231 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed"); 232 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 233 } 234 235 #endif 236 237 #elif defined(_LIBCPP_WIN32API) 238 239 // https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says: 240 // If the function fails, the return value is zero. <snip> 241 // On systems that run Windows XP or later, the function will always succeed 242 // and will thus never return zero. 243 244 static LARGE_INTEGER 245 __QueryPerformanceFrequency() 246 { 247 LARGE_INTEGER val; 248 (void) QueryPerformanceFrequency(&val); 249 return val; 250 } 251 252 static steady_clock::time_point __libcpp_steady_clock_now() { 253 static const LARGE_INTEGER freq = __QueryPerformanceFrequency(); 254 255 LARGE_INTEGER counter; 256 (void) QueryPerformanceCounter(&counter); 257 auto seconds = counter.QuadPart / freq.QuadPart; 258 auto fractions = counter.QuadPart % freq.QuadPart; 259 auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart; 260 return steady_clock::time_point(steady_clock::duration(dur)); 261 } 262 263 #elif defined(__MVS__) 264 265 static steady_clock::time_point __libcpp_steady_clock_now() { 266 struct timespec64 ts; 267 if (0 != gettimeofdayMonotonic(&ts)) 268 __throw_system_error(errno, "failed to obtain time of day"); 269 270 return steady_clock::time_point(seconds(ts.tv_sec) + nanoseconds(ts.tv_nsec)); 271 } 272 273 # elif defined(__Fuchsia__) 274 275 static steady_clock::time_point __libcpp_steady_clock_now() noexcept { 276 // Implicitly link against the vDSO system call ABI without 277 // requiring the final link to specify -lzircon explicitly when 278 // statically linking libc++. 279 # pragma comment(lib, "zircon") 280 281 return steady_clock::time_point(nanoseconds(_zx_clock_get_monotonic())); 282 } 283 284 # elif defined(CLOCK_MONOTONIC) 285 286 static steady_clock::time_point __libcpp_steady_clock_now() { 287 struct timespec tp; 288 if (0 != clock_gettime(CLOCK_MONOTONIC, &tp)) 289 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed"); 290 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 291 } 292 293 # else 294 # error "Monotonic clock not implemented on this platform" 295 # endif 296 297 const bool steady_clock::is_steady; 298 299 steady_clock::time_point 300 steady_clock::now() noexcept 301 { 302 return __libcpp_steady_clock_now(); 303 } 304 305 #endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK 306 307 } 308 309 _LIBCPP_END_NAMESPACE_STD 310