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 <__system_error/system_error.h> 16 #include <cerrno> // errno 17 #include <chrono> 18 19 #if defined(__MVS__) 20 # include <__support/ibm/gettod_zos.h> // gettimeofdayMonotonic 21 #endif 22 23 #include "include/apple_availability.h" 24 #include <time.h> // clock_gettime and CLOCK_{MONOTONIC,REALTIME,MONOTONIC_RAW} 25 26 #if __has_include(<unistd.h>) 27 # include <unistd.h> // _POSIX_TIMERS 28 #endif 29 30 #if __has_include(<sys/time.h>) 31 # include <sys/time.h> // for gettimeofday and timeval 32 #endif 33 34 // OpenBSD does not have a fully conformant suite of POSIX timers, but 35 // it does have clock_gettime and CLOCK_MONOTONIC which is all we need. 36 #if defined(__APPLE__) || defined(__gnu_hurd__) || defined(__OpenBSD__) || (defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0) 37 # define _LIBCPP_HAS_CLOCK_GETTIME 38 #endif 39 40 #if defined(_LIBCPP_WIN32API) 41 # define WIN32_LEAN_AND_MEAN 42 # define VC_EXTRA_LEAN 43 # include <windows.h> 44 # if _WIN32_WINNT >= _WIN32_WINNT_WIN8 45 # include <winapifamily.h> 46 # endif 47 #endif // defined(_LIBCPP_WIN32API) 48 49 #if defined(__Fuchsia__) 50 # include <zircon/syscalls.h> 51 #endif 52 53 #if __has_include(<mach/mach_time.h>) 54 # include <mach/mach_time.h> 55 #endif 56 57 #if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB) 58 # pragma comment(lib, "rt") 59 #endif 60 61 _LIBCPP_BEGIN_NAMESPACE_STD 62 63 namespace chrono { 64 65 // 66 // system_clock 67 // 68 69 #if defined(_LIBCPP_WIN32API) 70 71 # if _WIN32_WINNT < _WIN32_WINNT_WIN8 72 73 namespace { 74 75 typedef void(WINAPI* GetSystemTimeAsFileTimePtr)(LPFILETIME); 76 77 class GetSystemTimeInit { 78 public: 79 GetSystemTimeInit() { 80 fp = 81 (GetSystemTimeAsFileTimePtr)GetProcAddress(GetModuleHandleW(L"kernel32.dll"), "GetSystemTimePreciseAsFileTime"); 82 if (fp == nullptr) 83 fp = GetSystemTimeAsFileTime; 84 } 85 GetSystemTimeAsFileTimePtr fp; 86 }; 87 88 // Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority 89 // attribute with a value that's reserved for the implementation (we're the implementation). 90 # include "chrono_system_time_init.h" 91 } // namespace 92 93 # endif 94 95 static system_clock::time_point __libcpp_system_clock_now() { 96 // FILETIME is in 100ns units 97 using filetime_duration = 98 std::chrono::duration<__int64, std::ratio_multiply<std::ratio<100, 1>, nanoseconds::period>>; 99 100 // The Windows epoch is Jan 1 1601, the Unix epoch Jan 1 1970. 101 static constexpr const seconds nt_to_unix_epoch{11644473600}; 102 103 FILETIME ft; 104 # if (_WIN32_WINNT >= _WIN32_WINNT_WIN8 && WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)) || \ 105 (_WIN32_WINNT >= _WIN32_WINNT_WIN10) 106 GetSystemTimePreciseAsFileTime(&ft); 107 # elif !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) 108 GetSystemTimeAsFileTime(&ft); 109 # else 110 GetSystemTimeAsFileTimeFunc.fp(&ft); 111 # endif 112 113 filetime_duration d{(static_cast<__int64>(ft.dwHighDateTime) << 32) | static_cast<__int64>(ft.dwLowDateTime)}; 114 return system_clock::time_point(duration_cast<system_clock::duration>(d - nt_to_unix_epoch)); 115 } 116 117 #elif defined(_LIBCPP_HAS_CLOCK_GETTIME) 118 119 static system_clock::time_point __libcpp_system_clock_now() { 120 struct timespec tp; 121 if (0 != clock_gettime(CLOCK_REALTIME, &tp)) 122 __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed"); 123 return system_clock::time_point(seconds(tp.tv_sec) + microseconds(tp.tv_nsec / 1000)); 124 } 125 126 #else 127 128 static system_clock::time_point __libcpp_system_clock_now() { 129 timeval tv; 130 gettimeofday(&tv, 0); 131 return system_clock::time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec)); 132 } 133 134 #endif 135 136 const bool system_clock::is_steady; 137 138 system_clock::time_point system_clock::now() noexcept { return __libcpp_system_clock_now(); } 139 140 time_t system_clock::to_time_t(const time_point& t) noexcept { 141 return time_t(duration_cast<seconds>(t.time_since_epoch()).count()); 142 } 143 144 system_clock::time_point system_clock::from_time_t(time_t t) noexcept { return system_clock::time_point(seconds(t)); } 145 146 // 147 // steady_clock 148 // 149 // Warning: If this is not truly steady, then it is non-conforming. It is 150 // better for it to not exist and have the rest of libc++ use system_clock 151 // instead. 152 // 153 154 #ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK 155 156 # if defined(__APPLE__) 157 158 // On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or 159 // mach_absolute_time are able to time functions in the nanosecond range. 160 // Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it 161 // also counts cycles when the system is asleep. Thus, it is the only 162 // acceptable implementation of steady_clock. 163 static steady_clock::time_point __libcpp_steady_clock_now() { 164 struct timespec tp; 165 if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp)) 166 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed"); 167 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 168 } 169 170 # elif defined(_LIBCPP_WIN32API) 171 172 // https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says: 173 // If the function fails, the return value is zero. <snip> 174 // On systems that run Windows XP or later, the function will always succeed 175 // and will thus never return zero. 176 177 static LARGE_INTEGER __QueryPerformanceFrequency() { 178 LARGE_INTEGER val; 179 (void)QueryPerformanceFrequency(&val); 180 return val; 181 } 182 183 static steady_clock::time_point __libcpp_steady_clock_now() { 184 static const LARGE_INTEGER freq = __QueryPerformanceFrequency(); 185 186 LARGE_INTEGER counter; 187 (void)QueryPerformanceCounter(&counter); 188 auto seconds = counter.QuadPart / freq.QuadPart; 189 auto fractions = counter.QuadPart % freq.QuadPart; 190 auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart; 191 return steady_clock::time_point(steady_clock::duration(dur)); 192 } 193 194 # elif defined(__MVS__) 195 196 static steady_clock::time_point __libcpp_steady_clock_now() { 197 struct timespec64 ts; 198 if (0 != gettimeofdayMonotonic(&ts)) 199 __throw_system_error(errno, "failed to obtain time of day"); 200 201 return steady_clock::time_point(seconds(ts.tv_sec) + nanoseconds(ts.tv_nsec)); 202 } 203 204 # elif defined(__Fuchsia__) 205 206 static steady_clock::time_point __libcpp_steady_clock_now() noexcept { 207 // Implicitly link against the vDSO system call ABI without 208 // requiring the final link to specify -lzircon explicitly when 209 // statically linking libc++. 210 # pragma comment(lib, "zircon") 211 212 return steady_clock::time_point(nanoseconds(_zx_clock_get_monotonic())); 213 } 214 215 # elif defined(_LIBCPP_HAS_CLOCK_GETTIME) 216 217 static steady_clock::time_point __libcpp_steady_clock_now() { 218 struct timespec tp; 219 if (0 != clock_gettime(CLOCK_MONOTONIC, &tp)) 220 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed"); 221 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); 222 } 223 224 # else 225 # error "Monotonic clock not implemented on this platform" 226 # endif 227 228 const bool steady_clock::is_steady; 229 230 steady_clock::time_point steady_clock::now() noexcept { return __libcpp_steady_clock_now(); } 231 232 #endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK 233 234 } // namespace chrono 235 236 _LIBCPP_END_NAMESPACE_STD 237