AuroraRuntime/Source/Time/Clock.cpp

322 lines
10 KiB
C++

/***
Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.
File: Clock.cpp
Date: 2021-6-13
Author: Reece
Note: Screw it, std::chrono has been widly shilled at C++11s answer to all these painful macros, asm linkage, and other shit youd have to do to pull clock
Semantics have changed over time. I remember when, in 2016 or something like this, msvcs implementation of chrono kept breaking things.
Every platform that remotely pretends to support a C++ toolchain has a chrono high performance clock. Any PC-like platform that uses clang and C++ more than likely uses a vendor hacked libc++ stl.
Seems portable enough. Worst case scenario, you're on a platform with a platform-specific high res clock function you could hack into here alongside portable timezone-unaware timegm/mktime functions somewhere else.
There is so much quirky shit one has to deal with when relying on instruction cycle counters and other such instructions, plus cycle to ~time pred, plus forced + direction only, atop non-standard [sometimes inline]
assembly, it's just not worth it to implement a CNTVCT_EL0 / RDSC / related userland client-app attempt of a high res clock.
I'll wave the white flag and use the STL in here for.now
***/
#include <Source/RuntimeInternal.hpp>
#include "Clock.hpp"
#if defined(AURORA_IS_MODERNNT_DERIVED)
// TODO (Reece): ....
// benchmarking:
// https://github.com/microsoft/STL/issues/2085
struct steady_clock_fast
{ // wraps QueryPerformanceCounter
using rep = long long;
using period = std::nano;
using duration = std::chrono::nanoseconds;
using time_point = _CHRONO time_point<steady_clock_fast>;
static constexpr bool is_steady = true;
_NODISCARD static time_point now() noexcept
{ // get current time
static const long long _Freq = _Query_perf_frequency(); // doesn't change after system boot
const long long _Ctr = _Query_perf_counter();
static_assert(period::num == 1, "This assumes period::num == 1.");
// Instead of just having "(_Ctr * period::den) / _Freq",
// the algorithm below prevents overflow when _Ctr is sufficiently large.
// It assumes that _Freq * period::den does not overflow, which is currently true for nano period.
// It is not realistic for _Ctr to accumulate to large values from zero with this assumption,
// but the initial value of _Ctr could be large.
// 10 MHz is a very common QPC frequency on modern PCs. Optimizing for
// this specific frequency can double the performance of this function by
// avoiding the expensive frequency conversion path.
if (_Freq == 10000000)
{
return time_point(duration(_Ctr * 100));
}
else
{
const long long _Whole = (_Ctr / _Freq) * period::den;
const long long _Part = (_Ctr % _Freq) * period::den / _Freq;
return time_point(duration(_Whole + _Part));
}
}
};
// ~3.0741 seconds
using high_res_clock = steady_clock_fast;
// holy fuck, we're keeping this
// ~2x improvement
#else
// ~6.07 seconds
using high_res_clock = std::chrono::high_resolution_clock;
#endif
using sys_clock = std::chrono::system_clock;
#if defined(AURORA_PLATFORM_WIN32)
#define timegm _mkgmtime
#endif
static sys_clock::duration gEpoch;
static sys_clock::duration gUnixDelta;
static auto InitEpoch()
{
std::tm start{0, 15, 10, 29, 7, 101, 0, 0, 0};
auto epoch = sys_clock::from_time_t(timegm(&start)).time_since_epoch();
std::tm unixStart{};
unixStart.tm_mday = 1;
unixStart.tm_year = 70;
// dont care what the spec says, you can't trust some ms stls
// sys_clock can have its own epoch for all we care
auto nixEpoch = sys_clock::from_time_t(timegm(&unixStart)).time_since_epoch();
gUnixDelta = epoch - nixEpoch;
gEpoch = epoch;
return 0;
}
static auto ___ = InitEpoch();
template<typename T>
static inline T NormalizeEpoch(T sysEpoch)
{
return sysEpoch - gEpoch;
}
template<typename T>
static inline T DecodeEpoch(T auroraEpoch)
{
return auroraEpoch + gEpoch;
}
template<typename Clock_t, typename Duration_t>
static auto TimeFromDurationSinceEpoch(Duration_t in)
{
auto duration = std::chrono::duration_cast<typename Clock_t::duration>(in);
return std::chrono::time_point<Clock_t>(DecodeEpoch(duration));
}
template<typename Duration_t>
static time_t CalculateTimeT(AuUInt64 in)
{
return sys_clock::to_time_t(TimeFromDurationSinceEpoch<sys_clock>(Duration_t(in)));
}
namespace Aurora::Time
{
AUKN_SYM time_t SToCTime(AuInt64 time)
{
return CalculateTimeT<std::chrono::seconds>(time);
}
AUKN_SYM time_t NSToCTime(AuInt64 time)
{
return CalculateTimeT<std::chrono::nanoseconds>(time);
}
AUKN_SYM time_t MSToCTime(AuInt64 time)
{
return CalculateTimeT<std::chrono::milliseconds>(time);
}
AUKN_SYM AuUInt64 CurrentClock()
{
return NormalizeEpoch(sys_clock::now().time_since_epoch()).count();
}
AUKN_SYM AuUInt64 CurrentClockMS()
{
return std::chrono::duration_cast<std::chrono::milliseconds>(NormalizeEpoch(sys_clock::now().time_since_epoch())).count();
}
AUKN_SYM AuUInt64 CurrentClockNS()
{
return std::chrono::duration_cast<std::chrono::nanoseconds>(NormalizeEpoch(sys_clock::now().time_since_epoch())).count();
}
AUKN_SYM AuInt64 CTimeToMS(time_t time)
{
return std::chrono::duration_cast<std::chrono::milliseconds>(NormalizeEpoch(sys_clock::from_time_t(time).time_since_epoch())).count();
}
AUKN_SYM AuUInt64 CurrentInternalClock()
{
return high_res_clock::now().time_since_epoch().count();
}
AUKN_SYM AuUInt64 CurrentInternalClockMS()
{
return std::chrono::duration_cast<std::chrono::milliseconds>(high_res_clock::now().time_since_epoch()).count();
}
AUKN_SYM AuUInt64 CurrentInternalClockNS()
{
return std::chrono::duration_cast<std::chrono::nanoseconds>(high_res_clock::now().time_since_epoch()).count();
}
AUKN_SYM AuInt64 ConvertAuroraToUnixMS(AuInt64 in)
{
return std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::milliseconds(in) + gUnixDelta).count();
}
AUKN_SYM AuInt64 ConvertAuroraToUnixNS(AuInt64 in)
{
return std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::nanoseconds(in) + gUnixDelta).count();
}
AUKN_SYM AuInt64 ConvertUnixToAuroraMS(AuInt64 in)
{
return std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::milliseconds(in) - gUnixDelta).count();
}
AUKN_SYM AuInt64 ConvertUnixToAuroraNS(AuInt64 in)
{
return std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::nanoseconds(in) - gUnixDelta).count();
}
AUKN_SYM AuUInt64 ConvertInternalToAuroraEpochMS(AuUInt64 in)
{
static AuInt64 epochDelta = 0;
if (epochDelta == 0)
{
epochDelta = CurrentClockMS() - CurrentInternalClockMS();
}
return epochDelta + in;
}
AUKN_SYM AuUInt64 ConvertInternalToAuroraEpochNS(AuUInt64 in)
{
static AuInt64 epochDelta = 0;
if (epochDelta == 0)
{
epochDelta = CurrentClockNS() - CurrentInternalClockNS();
}
return epochDelta + in;
}
AUKN_SYM double CPUFrequencyDeltaNS()
{
static double frequency = 0;
if (frequency != 0)
{
return frequency;
}
return frequency = (static_cast<double>(high_res_clock::period::num) / static_cast<double>(high_res_clock::period::den) * 1'000'000'000.f);
}
AUKN_SYM double CPUFrequencyDeltaMS()
{
static double frequency = 0;
if (frequency != 0)
{
return frequency;
}
return frequency = (static_cast<double>(high_res_clock::period::num) / static_cast<double>(high_res_clock::period::den) * 1'000.f);
}
AUKN_SYM AuUInt64 ClockJiffies()
{
static AuUInt64 frequency = 0;
if (frequency != 0)
{
return frequency;
}
return frequency = static_cast<double>(high_res_clock::period::den) / static_cast<double>(high_res_clock::period::num);
}
AUKN_SYM tm ToCivilTime(AuInt64 time, bool UTC)
{
std::tm ret {};
auto timet = MSToCTime(time);
if (UTC)
{
#if defined(AURORA_COMPILER_MSVC)
auto tm = gmtime_s(&ret, &timet);
#else
auto tm = gmtime_r(&timet, &ret);
#endif
#if defined(AURORA_COMPILER_MSVC)
SysAssert(!tm, "couldn't convert civil time");
#else
SysAssert(tm, "couldn't convert civil time");
#endif
}
else
{
#if defined(AURORA_COMPILER_MSVC)
if (localtime_s(&ret, &timet))
#else
if (!localtime_r(&timet, &ret))
#endif
{
AuLogWarn("Couldn't convert local civil time");
return ToCivilTime(time, true);
}
}
tm _;
_.CopyFrom(ret);
return _;
}
AUKN_SYM AuInt64 FromCivilTime(const tm &time, bool UTC)
{
::tm tm;
time_t timet;
time.CopyTo(tm);
if (UTC)
{
tm.tm_isdst = 0;
timet = timegm(&tm);
}
else
{
tm.tm_isdst = -1; // out of the 2 crts i've bothered to check, out of 3, this is legal
timet = mktime(&tm);
}
if ((timet == 0) || (timet == -1))
{
return 0;
}
return std::chrono::duration_cast<std::chrono::milliseconds>(NormalizeEpoch(std::chrono::system_clock::from_time_t(timet).time_since_epoch())).count();
}
AUKN_SYM tm NormalizeCivilTimezone(const Time::tm &time, ETimezoneShift shift)
{
if ((time.tm_isdst == 0) && (shift == ETimezoneShift::eUTC))
{
return time;
}
return ToCivilTime(FromCivilTime(time, shift == ETimezoneShift::eUTC));
}
}