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#include "dynlib.h"
#include "fasttime.h"
#include <util/generic/singleton.h>
#include <util/generic/yexception.h>
#include <utility>
#include <util/thread/singleton.h>
#if defined(_win_) || defined(_arm32_) || defined(_cygwin_)
ui64 InterpolatedMicroSeconds() {
return MicroSeconds();
}
#else
#include <dlfcn.h>
#include <sys/time.h>
#if defined(_musl_)
#include <util/generic/hash.h>
#include <util/generic/vector.h>
#include <util/generic/string.h>
#include <contrib/libs/linuxvdso/interface.h>
#endif
namespace {
using TTime = ui64;
struct TSymbols {
using TFunc = int (*)(struct timeval*, struct timezone*);
inline TSymbols()
: Func(nullptr)
{
// not DEFAULT, cause library/cpp/gettimeofday
Func = reinterpret_cast<TFunc>(dlsym(RTLD_NEXT, "gettimeofday"));
#if defined(_musl_)
if (!Func) {
Func = reinterpret_cast<TFunc>(NVdso::Function("__vdso_gettimeofday", "LINUX_2.6"));
}
#endif
if (!Func) {
Func = reinterpret_cast<TFunc>(Libc()->Sym("gettimeofday"));
}
}
inline TTime SystemTime() {
timeval tv;
Zero(tv);
Func(&tv, nullptr);
return (((TTime)1000000) * (TTime)tv.tv_sec) + (TTime)tv.tv_usec;
}
static inline THolder<TDynamicLibrary> OpenLibc() {
const char* libs[] = {
"/lib/libc.so.8",
"/lib/libc.so.7",
"/lib/libc.so.6",
};
for (auto& lib : libs) {
try {
return MakeHolder<TDynamicLibrary>(lib);
} catch (...) {
// ¯\_(ツ)_/¯
}
}
ythrow yexception() << "can not load libc";
}
inline TDynamicLibrary* Libc() {
if (!Lib) {
Lib = OpenLibc();
}
return Lib.Get();
}
THolder<TDynamicLibrary> Lib;
TFunc Func;
};
static inline TTime SystemTime() {
return Singleton<TSymbols>()->SystemTime();
}
struct TInitialTimes {
inline TInitialTimes()
: ITime(TimeBase())
, IProc(RdtscBase())
{
}
static TTime RdtscBase() {
return GetCycleCount() / (TTime)1000;
}
static TTime TimeBase() {
return SystemTime();
}
inline TTime Rdtsc() {
return RdtscBase() - IProc;
}
inline TTime Time() {
return TimeBase() - ITime;
}
const TTime ITime;
const TTime IProc;
};
template <size_t N, class A, class B>
class TLinePredictor {
public:
using TSample = std::pair<A, B>;
inline TLinePredictor()
: C_(0)
, A_(0)
, B_(0)
{
}
inline void Add(const A& a, const B& b) noexcept {
Add(TSample(a, b));
}
inline void Add(const TSample& s) noexcept {
S_[(C_++) % N] = s;
if (C_ > 1) {
ReCalc();
}
}
inline B Predict(A a) const noexcept {
return A_ + a * B_;
}
inline size_t Size() const noexcept {
return C_;
}
inline bool Enough() const noexcept {
return Size() >= N;
}
inline A LastX() const noexcept {
return S_[(C_ - 1) % N].first;
}
private:
inline void ReCalc() noexcept {
const size_t n = Min(N, C_);
double sx = 0;
double sy = 0;
double sxx = 0;
double sxy = 0;
for (size_t i = 0; i < n; ++i) {
const double x = S_[i].first;
const double y = S_[i].second;
sx += x;
sy += y;
sxx += x * x;
sxy += x * y;
}
B_ = (n * sxy - sx * sy) / (n * sxx - sx * sx);
A_ = (sy - B_ * sx) / n;
}
private:
size_t C_;
TSample S_[N];
double A_;
double B_;
};
class TTimePredictor: public TInitialTimes {
public:
inline TTimePredictor()
: Next_(1)
{
}
inline TTime Get() {
return GetBase() + ITime;
}
private:
inline TTime GetBase() {
const TTime x = Rdtsc();
if (TimeToSync(x)) {
const TTime y = Time();
P_.Add(x, y);
return y;
}
if (P_.Enough()) {
return P_.Predict(x);
}
return Time();
}
inline bool TimeToSync(TTime x) {
if (x > Next_) {
Next_ = Min(x + x / 10, x + 1000000);
return true;
}
return false;
}
private:
TLinePredictor<16, TTime, TTime> P_;
TTime Next_;
};
}
ui64 InterpolatedMicroSeconds() {
return FastTlsSingleton<TTimePredictor>()->Get();
}
#endif
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