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