diff options
Diffstat (limited to 'libcxx/src/chrono.cpp')
| -rw-r--r-- | libcxx/src/chrono.cpp | 120 |
1 files changed, 31 insertions, 89 deletions
diff --git a/libcxx/src/chrono.cpp b/libcxx/src/chrono.cpp index 9d448b6a985b..f0a5d50ddf77 100644 --- a/libcxx/src/chrono.cpp +++ b/libcxx/src/chrono.cpp @@ -9,36 +9,32 @@ #include "chrono" #include "cerrno" // errno #include "system_error" // __throw_system_error -#include <time.h> // clock_gettime, CLOCK_MONOTONIC and CLOCK_REALTIME +#include <time.h> // clock_gettime and CLOCK_{MONOTONIC,REALTIME,MONOTONIC_RAW} #include "include/apple_availability.h" -#if !defined(__APPLE__) +#if __has_include(<unistd.h>) +#include <unistd.h> +#endif + +#if !defined(__APPLE__) && _POSIX_TIMERS > 0 #define _LIBCPP_USE_CLOCK_GETTIME -#endif // __APPLE__ +#endif #if defined(_LIBCPP_WIN32API) -#define WIN32_LEAN_AND_MEAN -#define VC_EXTRA_LEAN -#include <windows.h> -#if _WIN32_WINNT >= _WIN32_WINNT_WIN8 -#include <winapifamily.h> -#endif +# define WIN32_LEAN_AND_MEAN +# define VC_EXTRA_LEAN +# include <windows.h> +# if _WIN32_WINNT >= _WIN32_WINNT_WIN8 +# include <winapifamily.h> +# endif #else -#if !defined(CLOCK_REALTIME) || !defined(_LIBCPP_USE_CLOCK_GETTIME) -#include <sys/time.h> // for gettimeofday and timeval -#endif // !defined(CLOCK_REALTIME) +# if !defined(CLOCK_REALTIME) +# include <sys/time.h> // for gettimeofday and timeval +# endif // !defined(CLOCK_REALTIME) #endif // defined(_LIBCPP_WIN32API) -#if !defined(_LIBCPP_HAS_NO_MONOTONIC_CLOCK) -#if __APPLE__ -#include <mach/mach_time.h> // mach_absolute_time, mach_timebase_info_data_t -#elif !defined(_LIBCPP_WIN32API) && !defined(CLOCK_MONOTONIC) -#error "Monotonic clock not implemented" -#endif -#endif - #if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB) -#pragma comment(lib, "rt") +# pragma comment(lib, "rt") #endif _LIBCPP_BEGIN_NAMESPACE_STD @@ -78,7 +74,7 @@ system_clock::now() _NOEXCEPT static_cast<__int64>(ft.dwLowDateTime)}; return time_point(duration_cast<duration>(d - nt_to_unix_epoch)); #else -#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_REALTIME) +#if defined(CLOCK_REALTIME) struct timespec tp; if (0 != clock_gettime(CLOCK_REALTIME, &tp)) __throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed"); @@ -87,7 +83,7 @@ system_clock::now() _NOEXCEPT timeval tv; gettimeofday(&tv, 0); return time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec)); -#endif // _LIBCPP_USE_CLOCK_GETTIME && CLOCK_REALTIME +#endif // CLOCK_REALTIME #endif } @@ -114,71 +110,24 @@ const bool steady_clock::is_steady; #if defined(__APPLE__) -// Darwin libc versions >= 1133 provide ns precision via CLOCK_UPTIME_RAW -#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_UPTIME_RAW) +#if !defined(CLOCK_MONOTONIC_RAW) +# error "Building libc++ on Apple platforms requires CLOCK_MONOTONIC_RAW" +#endif + +// On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or +// mach_absolute_time are able to time functions in the nanosecond range. +// Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it +// also counts cycles when the system is asleep. Thus, it is the only +// acceptable implementation of steady_clock. steady_clock::time_point steady_clock::now() _NOEXCEPT { struct timespec tp; - if (0 != clock_gettime(CLOCK_UPTIME_RAW, &tp)) - __throw_system_error(errno, "clock_gettime(CLOCK_UPTIME_RAW) failed"); + if (0 != clock_gettime(CLOCK_MONOTONIC_RAW, &tp)) + __throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC_RAW) failed"); return time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec)); } -#else -// mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of -// nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom -// are run time constants supplied by the OS. This clock has no relationship -// to the Gregorian calendar. It's main use is as a high resolution timer. - -// MachInfo.numer / MachInfo.denom is often 1 on the latest equipment. Specialize -// for that case as an optimization. - -static -steady_clock::rep -steady_simplified() -{ - return static_cast<steady_clock::rep>(mach_absolute_time()); -} - -static -double -compute_steady_factor() -{ - mach_timebase_info_data_t MachInfo; - mach_timebase_info(&MachInfo); - return static_cast<double>(MachInfo.numer) / MachInfo.denom; -} - -static -steady_clock::rep -steady_full() -{ - static const double factor = compute_steady_factor(); - return static_cast<steady_clock::rep>(mach_absolute_time() * factor); -} - -typedef steady_clock::rep (*FP)(); - -static -FP -init_steady_clock() -{ - mach_timebase_info_data_t MachInfo; - mach_timebase_info(&MachInfo); - if (MachInfo.numer == MachInfo.denom) - return &steady_simplified; - return &steady_full; -} - -steady_clock::time_point -steady_clock::now() _NOEXCEPT -{ - static FP fp = init_steady_clock(); - return time_point(duration(fp())); -} -#endif // defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_UPTIME_RAW) - #elif defined(_LIBCPP_WIN32API) // https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says: @@ -206,13 +155,6 @@ steady_clock::now() _NOEXCEPT #elif defined(CLOCK_MONOTONIC) -// On Apple platforms only CLOCK_UPTIME_RAW or mach_absolute_time are able to -// time functions in the nanosecond range. Thus, they are the only acceptable -// implementations of steady_clock. -#ifdef __APPLE__ -#error "Never use CLOCK_MONOTONIC for steady_clock::now on Apple platforms" -#endif - steady_clock::time_point steady_clock::now() _NOEXCEPT { @@ -223,7 +165,7 @@ steady_clock::now() _NOEXCEPT } #else -#error "Monotonic clock not implemented" +# error "Monotonic clock not implemented" #endif #endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK |