libcxx/src/chrono.cpp

   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 <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> // _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 //
  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 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(_LIBCPP_HAS_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 // On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or
 171 // mach_absolute_time are able to time functions in the nanosecond range.
 172 // Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it
 173 // also counts cycles when the system is asleep. Thus, it is the only
 174 // acceptable implementation of steady_clock.
 175 static steady_clock::time_point __libcpp_steady_clock_now() {
 176     struct timespec tp;
 177     if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp))
 178         __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed");
 179     return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
 180 }
 181
 182 #elif defined(_LIBCPP_WIN32API)
 183
 184 // https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says:
 185 //    If the function fails, the return value is zero. <snip>
 186 //    On systems that run Windows XP or later, the function will always succeed
 187 //      and will thus never return zero.
 188
 189 static LARGE_INTEGER
 190 __QueryPerformanceFrequency()
 191 {
 192     LARGE_INTEGER val;
 193     (void) QueryPerformanceFrequency(&val);
 194     return val;
 195 }
 196
 197 static steady_clock::time_point __libcpp_steady_clock_now() {
 198   static const LARGE_INTEGER freq = __QueryPerformanceFrequency();
 199
 200   LARGE_INTEGER counter;
 201   (void) QueryPerformanceCounter(&counter);
 202   auto seconds = counter.QuadPart / freq.QuadPart;
 203   auto fractions = counter.QuadPart % freq.QuadPart;
 204   auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart;
 205   return steady_clock::time_point(steady_clock::duration(dur));
 206 }
 207
 208 #elif defined(__MVS__)
 209
 210 static steady_clock::time_point __libcpp_steady_clock_now() {
 211   struct timespec64 ts;
 212   if (0 != gettimeofdayMonotonic(&ts))
 213     __throw_system_error(errno, "failed to obtain time of day");
 214
 215   return steady_clock::time_point(seconds(ts.tv_sec) + nanoseconds(ts.tv_nsec));
 216 }
 217
 218 #  elif defined(__Fuchsia__)
 219
 220 static steady_clock::time_point __libcpp_steady_clock_now() noexcept {
 221   // Implicitly link against the vDSO system call ABI without
 222   // requiring the final link to specify -lzircon explicitly when
 223   // statically linking libc++.
 224 #    pragma comment(lib, "zircon")
 225
 226   return steady_clock::time_point(nanoseconds(_zx_clock_get_monotonic()));
 227 }
 228
 229 #  elif defined(_LIBCPP_HAS_CLOCK_GETTIME)
 230
 231 static steady_clock::time_point __libcpp_steady_clock_now() {
 232     struct timespec tp;
 233     if (0 != clock_gettime(CLOCK_MONOTONIC, &tp))
 234         __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed");
 235     return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
 236 }
 237
 238 #  else
 239 #    error "Monotonic clock not implemented on this platform"
 240 #  endif
 241
 242 const bool steady_clock::is_steady;
 243
 244 steady_clock::time_point
 245 steady_clock::now() noexcept
 246 {
 247     return __libcpp_steady_clock_now();
 248 }
 249
 250 #endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK
 251
 252 }
 253
 254 _LIBCPP_END_NAMESPACE_STD