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:
GetSystemTimeInit()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 # 83 "chrono.cpp" 1 3
84 GetSystemTimeInit GetSystemTimeAsFileTimeFunc _LIBCPP_INIT_PRIORITY_MAX;
85 # 85 "chrono.cpp" 2
86 } // namespace
87
88 #endif
89
__libcpp_system_clock_now()90 static system_clock::time_point __libcpp_system_clock_now() {
91 // FILETIME is in 100ns units
92 using filetime_duration =
93 _VSTD::chrono::duration<__int64,
94 _VSTD::ratio_multiply<_VSTD::ratio<100, 1>,
95 nanoseconds::period>>;
96
97 // The Windows epoch is Jan 1 1601, the Unix epoch Jan 1 1970.
98 static _LIBCPP_CONSTEXPR const seconds nt_to_unix_epoch{11644473600};
99
100 FILETIME ft;
101 #if (_WIN32_WINNT >= _WIN32_WINNT_WIN8 && WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)) || \
102 (_WIN32_WINNT >= _WIN32_WINNT_WIN10)
103 GetSystemTimePreciseAsFileTime(&ft);
104 #elif !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
105 GetSystemTimeAsFileTime(&ft);
106 #else
107 GetSystemTimeAsFileTimeFunc.fp(&ft);
108 #endif
109
110 filetime_duration d{(static_cast<__int64>(ft.dwHighDateTime) << 32) |
111 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(CLOCK_REALTIME) && defined(_LIBCPP_USE_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
now()137 system_clock::now() noexcept
138 {
139 return __libcpp_system_clock_now();
140 }
141
142 time_t
to_time_t(const time_point & t)143 system_clock::to_time_t(const time_point& t) noexcept
144 {
145 return time_t(duration_cast<seconds>(t.time_since_epoch()).count());
146 }
147
148 system_clock::time_point
from_time_t(time_t t)149 system_clock::from_time_t(time_t t) noexcept
150 {
151 return system_clock::time_point(seconds(t));
152 }
153
154 //
155 // steady_clock
156 //
157 // Warning: If this is not truly steady, then it is non-conforming. It is
158 // better for it to not exist and have the rest of libc++ use system_clock
159 // instead.
160 //
161
162 #ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK
163
164 #if defined(__APPLE__)
165
166 // TODO(ldionne):
167 // This old implementation of steady_clock is retained until Chrome drops supports
168 // for macOS < 10.12. The issue is that they link libc++ statically into their
169 // application, which means that libc++ must support being built for such deployment
170 // targets. See https://llvm.org/D74489 for details.
171 #if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101200) || \
172 (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 100000) || \
173 (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 100000) || \
174 (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 30000)
175 # define _LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME
176 #endif
177
178 #if defined(_LIBCPP_USE_OLD_MACH_ABSOLUTE_TIME)
179
180 // mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of
181 // nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom
182 // are run time constants supplied by the OS. This clock has no relationship
183 // to the Gregorian calendar. It's main use is as a high resolution timer.
184
185 // MachInfo.numer / MachInfo.denom is often 1 on the latest equipment. Specialize
186 // for that case as an optimization.
187
steady_simplified()188 static steady_clock::rep steady_simplified() {
189 return static_cast<steady_clock::rep>(mach_absolute_time());
190 }
compute_steady_factor()191 static double compute_steady_factor() {
192 mach_timebase_info_data_t MachInfo;
193 mach_timebase_info(&MachInfo);
194 return static_cast<double>(MachInfo.numer) / MachInfo.denom;
195 }
196
steady_full()197 static steady_clock::rep steady_full() {
198 static const double factor = compute_steady_factor();
199 return static_cast<steady_clock::rep>(mach_absolute_time() * factor);
200 }
201
202 typedef steady_clock::rep (*FP)();
203
init_steady_clock()204 static FP init_steady_clock() {
205 mach_timebase_info_data_t MachInfo;
206 mach_timebase_info(&MachInfo);
207 if (MachInfo.numer == MachInfo.denom)
208 return &steady_simplified;
209 return &steady_full;
210 }
211
__libcpp_steady_clock_now()212 static steady_clock::time_point __libcpp_steady_clock_now() {
213 static FP fp = init_steady_clock();
214 return steady_clock::time_point(steady_clock::duration(fp()));
215 }
216
217 #else // vvvvv default behavior for Apple platforms vvvvv
218
219 // On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or
220 // mach_absolute_time are able to time functions in the nanosecond range.
221 // Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it
222 // also counts cycles when the system is asleep. Thus, it is the only
223 // acceptable implementation of steady_clock.
__libcpp_steady_clock_now()224 static steady_clock::time_point __libcpp_steady_clock_now() {
225 struct timespec tp;
226 if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp))
227 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed");
228 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
229 }
230
231 #endif
232
233 #elif defined(_LIBCPP_WIN32API)
234
235 // https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says:
236 // If the function fails, the return value is zero. <snip>
237 // On systems that run Windows XP or later, the function will always succeed
238 // and will thus never return zero.
239
240 static LARGE_INTEGER
__QueryPerformanceFrequency()241 __QueryPerformanceFrequency()
242 {
243 LARGE_INTEGER val;
244 (void) QueryPerformanceFrequency(&val);
245 return val;
246 }
247
__libcpp_steady_clock_now()248 static steady_clock::time_point __libcpp_steady_clock_now() {
249 static const LARGE_INTEGER freq = __QueryPerformanceFrequency();
250
251 LARGE_INTEGER counter;
252 (void) QueryPerformanceCounter(&counter);
253 auto seconds = counter.QuadPart / freq.QuadPart;
254 auto fractions = counter.QuadPart % freq.QuadPart;
255 auto dur = seconds * nano::den + fractions * nano::den / freq.QuadPart;
256 return steady_clock::time_point(steady_clock::duration(dur));
257 }
258
259 #elif defined(__MVS__)
260
__libcpp_steady_clock_now()261 static steady_clock::time_point __libcpp_steady_clock_now() {
262 struct timespec64 ts;
263 if (0 != gettimeofdayMonotonic(&ts))
264 __throw_system_error(errno, "failed to obtain time of day");
265
266 return steady_clock::time_point(seconds(ts.tv_sec) + nanoseconds(ts.tv_nsec));
267 }
268
269 #elif defined(CLOCK_MONOTONIC)
270
__libcpp_steady_clock_now()271 static steady_clock::time_point __libcpp_steady_clock_now() {
272 struct timespec tp;
273 if (0 != clock_gettime(CLOCK_MONOTONIC, &tp))
274 __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed");
275 return steady_clock::time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
276 }
277
278 #else
279 # error "Monotonic clock not implemented on this platform"
280 #endif
281
282 const bool steady_clock::is_steady;
283
284 steady_clock::time_point
now()285 steady_clock::now() noexcept
286 {
287 return __libcpp_steady_clock_now();
288 }
289
290 #endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK
291
292 }
293
294 _LIBCPP_END_NAMESPACE_STD
295