path: root/contrib/restricted/abseil-cpp-tstring/y_absl/time/duration.cc

// Copyright 2017 The Abseil Authors. 
// 
// Licensed under the Apache License, Version 2.0 (the "License"); 
// you may not use this file except in compliance with the License. 
// You may obtain a copy of the License at 
// 
//      https://www.apache.org/licenses/LICENSE-2.0 
// 
// Unless required by applicable law or agreed to in writing, software 
// distributed under the License is distributed on an "AS IS" BASIS, 
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
// See the License for the specific language governing permissions and 
// limitations under the License. 
 
// The implementation of the y_absl::Duration class, which is declared in
// //y_absl/time.h.  This class behaves like a numeric type; it has no public
// methods and is used only through the operators defined here. 
// 
// Implementation notes: 
// 
// An y_absl::Duration is represented as
// 
//   rep_hi_ : (int64_t)  Whole seconds 
//   rep_lo_ : (uint32_t) Fractions of a second 
// 
// The seconds value (rep_hi_) may be positive or negative as appropriate. 
// The fractional seconds (rep_lo_) is always a positive offset from rep_hi_. 
// The API for Duration guarantees at least nanosecond resolution, which 
// means rep_lo_ could have a max value of 1B - 1 if it stored nanoseconds. 
// However, to utilize more of the available 32 bits of space in rep_lo_, 
// we instead store quarters of a nanosecond in rep_lo_ resulting in a max 
// value of 4B - 1.  This allows us to correctly handle calculations like 
// 0.5 nanos + 0.5 nanos = 1 nano.  The following example shows the actual 
// Duration rep using quarters of a nanosecond. 
// 
//    2.5 sec = {rep_hi_=2,  rep_lo_=2000000000}  // lo = 4 * 500000000 
//   -2.5 sec = {rep_hi_=-3, rep_lo_=2000000000} 
// 
// Infinite durations are represented as Durations with the rep_lo_ field set 
// to all 1s. 
// 
//   +InfiniteDuration: 
//     rep_hi_ : kint64max 
//     rep_lo_ : ~0U 
// 
//   -InfiniteDuration: 
//     rep_hi_ : kint64min 
//     rep_lo_ : ~0U 
// 
// Arithmetic overflows/underflows to +/- infinity and saturates. 
 
#if defined(_MSC_VER) 
#include <winsock2.h>  // for timeval 
#endif 
 
#include <algorithm> 
#include <cassert> 
#include <cctype> 
#include <cerrno> 
#include <cmath> 
#include <cstdint> 
#include <cstdlib> 
#include <cstring> 
#include <ctime> 
#include <functional> 
#include <limits> 
#include <util/generic/string.h>
 
#include "y_absl/base/casts.h"
#include "y_absl/base/macros.h"
#include "y_absl/numeric/int128.h"
#include "y_absl/strings/string_view.h"
#include "y_absl/strings/strip.h"
#include "y_absl/time/time.h"
 
namespace y_absl {
ABSL_NAMESPACE_BEGIN
 
namespace { 
 
using time_internal::kTicksPerNanosecond; 
using time_internal::kTicksPerSecond; 
 
constexpr int64_t kint64max = std::numeric_limits<int64_t>::max(); 
constexpr int64_t kint64min = std::numeric_limits<int64_t>::min(); 
 
// Can't use std::isinfinite() because it doesn't exist on windows. 
inline bool IsFinite(double d) { 
  if (std::isnan(d)) return false; 
  return d != std::numeric_limits<double>::infinity() && 
         d != -std::numeric_limits<double>::infinity(); 
} 
 
inline bool IsValidDivisor(double d) { 
  if (std::isnan(d)) return false; 
  return d != 0.0; 
} 
 
// Can't use std::round() because it is only available in C++11. 
// Note that we ignore the possibility of floating-point over/underflow. 
template <typename Double> 
inline double Round(Double d) { 
  return d < 0 ? std::ceil(d - 0.5) : std::floor(d + 0.5); 
} 
 
// *sec may be positive or negative.  *ticks must be in the range 
// -kTicksPerSecond < *ticks < kTicksPerSecond.  If *ticks is negative it 
// will be normalized to a positive value by adjusting *sec accordingly. 
inline void NormalizeTicks(int64_t* sec, int64_t* ticks) { 
  if (*ticks < 0) { 
    --*sec; 
    *ticks += kTicksPerSecond; 
  } 
} 
 
// Makes a uint128 from the absolute value of the given scalar. 
inline uint128 MakeU128(int64_t a) { 
  uint128 u128 = 0; 
  if (a < 0) { 
    ++u128; 
    ++a;  // Makes it safe to negate 'a' 
    a = -a; 
  } 
  u128 += static_cast<uint64_t>(a); 
  return u128; 
} 
 
// Makes a uint128 count of ticks out of the absolute value of the Duration. 
inline uint128 MakeU128Ticks(Duration d) { 
  int64_t rep_hi = time_internal::GetRepHi(d); 
  uint32_t rep_lo = time_internal::GetRepLo(d); 
  if (rep_hi < 0) { 
    ++rep_hi; 
    rep_hi = -rep_hi; 
    rep_lo = kTicksPerSecond - rep_lo; 
  } 
  uint128 u128 = static_cast<uint64_t>(rep_hi); 
  u128 *= static_cast<uint64_t>(kTicksPerSecond); 
  u128 += rep_lo; 
  return u128; 
} 
 
// Breaks a uint128 of ticks into a Duration. 
inline Duration MakeDurationFromU128(uint128 u128, bool is_neg) { 
  int64_t rep_hi; 
  uint32_t rep_lo; 
  const uint64_t h64 = Uint128High64(u128); 
  const uint64_t l64 = Uint128Low64(u128); 
  if (h64 == 0) {  // fastpath 
    const uint64_t hi = l64 / kTicksPerSecond; 
    rep_hi = static_cast<int64_t>(hi); 
    rep_lo = static_cast<uint32_t>(l64 - hi * kTicksPerSecond); 
  } else { 
    // kMaxRepHi64 is the high 64 bits of (2^63 * kTicksPerSecond). 
    // Any positive tick count whose high 64 bits are >= kMaxRepHi64 
    // is not representable as a Duration.  A negative tick count can 
    // have its high 64 bits == kMaxRepHi64 but only when the low 64 
    // bits are all zero, otherwise it is not representable either. 
    const uint64_t kMaxRepHi64 = 0x77359400UL; 
    if (h64 >= kMaxRepHi64) { 
      if (is_neg && h64 == kMaxRepHi64 && l64 == 0) { 
        // Avoid trying to represent -kint64min below. 
        return time_internal::MakeDuration(kint64min); 
      } 
      return is_neg ? -InfiniteDuration() : InfiniteDuration(); 
    } 
    const uint128 kTicksPerSecond128 = static_cast<uint64_t>(kTicksPerSecond); 
    const uint128 hi = u128 / kTicksPerSecond128; 
    rep_hi = static_cast<int64_t>(Uint128Low64(hi)); 
    rep_lo = 
        static_cast<uint32_t>(Uint128Low64(u128 - hi * kTicksPerSecond128)); 
  } 
  if (is_neg) { 
    rep_hi = -rep_hi; 
    if (rep_lo != 0) { 
      --rep_hi; 
      rep_lo = kTicksPerSecond - rep_lo; 
    } 
  } 
  return time_internal::MakeDuration(rep_hi, rep_lo); 
} 
 
// Convert between int64_t and uint64_t, preserving representation. This 
// allows us to do arithmetic in the unsigned domain, where overflow has 
// well-defined behavior. See operator+=() and operator-=(). 
// 
// C99 7.20.1.1.1, as referenced by C++11 18.4.1.2, says, "The typedef 
// name intN_t designates a signed integer type with width N, no padding 
// bits, and a two's complement representation." So, we can convert to 
// and from the corresponding uint64_t value using a bit cast. 
inline uint64_t EncodeTwosComp(int64_t v) { 
  return y_absl::bit_cast<uint64_t>(v);
} 
inline int64_t DecodeTwosComp(uint64_t v) { return y_absl::bit_cast<int64_t>(v); }
 
// Note: The overflow detection in this function is done using greater/less *or 
// equal* because kint64max/min is too large to be represented exactly in a 
// double (which only has 53 bits of precision). In order to avoid assigning to 
// rep->hi a double value that is too large for an int64_t (and therefore is 
// undefined), we must consider computations that equal kint64max/min as a 
// double as overflow cases. 
inline bool SafeAddRepHi(double a_hi, double b_hi, Duration* d) { 
  double c = a_hi + b_hi; 
  if (c >= static_cast<double>(kint64max)) { 
    *d = InfiniteDuration(); 
    return false; 
  } 
  if (c <= static_cast<double>(kint64min)) { 
    *d = -InfiniteDuration(); 
    return false; 
  } 
  *d = time_internal::MakeDuration(c, time_internal::GetRepLo(*d)); 
  return true; 
} 
 
// A functor that's similar to std::multiplies<T>, except this returns the max 
// T value instead of overflowing. This is only defined for uint128. 
template <typename Ignored> 
struct SafeMultiply { 
  uint128 operator()(uint128 a, uint128 b) const { 
    // b hi is always zero because it originated as an int64_t. 
    assert(Uint128High64(b) == 0); 
    // Fastpath to avoid the expensive overflow check with division. 
    if (Uint128High64(a) == 0) { 
      return (((Uint128Low64(a) | Uint128Low64(b)) >> 32) == 0) 
                 ? static_cast<uint128>(Uint128Low64(a) * Uint128Low64(b)) 
                 : a * b; 
    } 
    return b == 0 ? b : (a > kuint128max / b) ? kuint128max : a * b; 
  } 
}; 
 
// Scales (i.e., multiplies or divides, depending on the Operation template) 
// the Duration d by the int64_t r. 
template <template <typename> class Operation> 
inline Duration ScaleFixed(Duration d, int64_t r) { 
  const uint128 a = MakeU128Ticks(d); 
  const uint128 b = MakeU128(r); 
  const uint128 q = Operation<uint128>()(a, b); 
  const bool is_neg = (time_internal::GetRepHi(d) < 0) != (r < 0); 
  return MakeDurationFromU128(q, is_neg); 
} 
 
// Scales (i.e., multiplies or divides, depending on the Operation template) 
// the Duration d by the double r. 
template <template <typename> class Operation> 
inline Duration ScaleDouble(Duration d, double r) { 
  Operation<double> op; 
  double hi_doub = op(time_internal::GetRepHi(d), r); 
  double lo_doub = op(time_internal::GetRepLo(d), r); 
 
  double hi_int = 0; 
  double hi_frac = std::modf(hi_doub, &hi_int); 
 
  // Moves hi's fractional bits to lo. 
  lo_doub /= kTicksPerSecond; 
  lo_doub += hi_frac; 
 
  double lo_int = 0; 
  double lo_frac = std::modf(lo_doub, &lo_int); 
 
  // Rolls lo into hi if necessary. 
  int64_t lo64 = Round(lo_frac * kTicksPerSecond); 
 
  Duration ans; 
  if (!SafeAddRepHi(hi_int, lo_int, &ans)) return ans; 
  int64_t hi64 = time_internal::GetRepHi(ans); 
  if (!SafeAddRepHi(hi64, lo64 / kTicksPerSecond, &ans)) return ans; 
  hi64 = time_internal::GetRepHi(ans); 
  lo64 %= kTicksPerSecond; 
  NormalizeTicks(&hi64, &lo64); 
  return time_internal::MakeDuration(hi64, lo64); 
} 
 
// Tries to divide num by den as fast as possible by looking for common, easy 
// cases. If the division was done, the quotient is in *q and the remainder is 
// in *rem and true will be returned. 
inline bool IDivFastPath(const Duration num, const Duration den, int64_t* q, 
                         Duration* rem) { 
  // Bail if num or den is an infinity. 
  if (time_internal::IsInfiniteDuration(num) || 
      time_internal::IsInfiniteDuration(den)) 
    return false; 
 
  int64_t num_hi = time_internal::GetRepHi(num); 
  uint32_t num_lo = time_internal::GetRepLo(num); 
  int64_t den_hi = time_internal::GetRepHi(den); 
  uint32_t den_lo = time_internal::GetRepLo(den); 
 
  if (den_hi == 0 && den_lo == kTicksPerNanosecond) { 
    // Dividing by 1ns 
    if (num_hi >= 0 && num_hi < (kint64max - kTicksPerSecond) / 1000000000) { 
      *q = num_hi * 1000000000 + num_lo / kTicksPerNanosecond; 
      *rem = time_internal::MakeDuration(0, num_lo % den_lo); 
      return true; 
    } 
  } else if (den_hi == 0 && den_lo == 100 * kTicksPerNanosecond) { 
    // Dividing by 100ns (common when converting to Universal time) 
    if (num_hi >= 0 && num_hi < (kint64max - kTicksPerSecond) / 10000000) { 
      *q = num_hi * 10000000 + num_lo / (100 * kTicksPerNanosecond); 
      *rem = time_internal::MakeDuration(0, num_lo % den_lo); 
      return true; 
    } 
  } else if (den_hi == 0 && den_lo == 1000 * kTicksPerNanosecond) { 
    // Dividing by 1us 
    if (num_hi >= 0 && num_hi < (kint64max - kTicksPerSecond) / 1000000) { 
      *q = num_hi * 1000000 + num_lo / (1000 * kTicksPerNanosecond); 
      *rem = time_internal::MakeDuration(0, num_lo % den_lo); 
      return true; 
    } 
  } else if (den_hi == 0 && den_lo == 1000000 * kTicksPerNanosecond) { 
    // Dividing by 1ms 
    if (num_hi >= 0 && num_hi < (kint64max - kTicksPerSecond) / 1000) { 
      *q = num_hi * 1000 + num_lo / (1000000 * kTicksPerNanosecond); 
      *rem = time_internal::MakeDuration(0, num_lo % den_lo); 
      return true; 
    } 
  } else if (den_hi > 0 && den_lo == 0) { 
    // Dividing by positive multiple of 1s 
    if (num_hi >= 0) { 
      if (den_hi == 1) { 
        *q = num_hi; 
        *rem = time_internal::MakeDuration(0, num_lo); 
        return true; 
      } 
      *q = num_hi / den_hi; 
      *rem = time_internal::MakeDuration(num_hi % den_hi, num_lo); 
      return true; 
    } 
    if (num_lo != 0) { 
      num_hi += 1; 
    } 
    int64_t quotient = num_hi / den_hi; 
    int64_t rem_sec = num_hi % den_hi; 
    if (rem_sec > 0) { 
      rem_sec -= den_hi; 
      quotient += 1; 
    } 
    if (num_lo != 0) { 
      rem_sec -= 1; 
    } 
    *q = quotient; 
    *rem = time_internal::MakeDuration(rem_sec, num_lo); 
    return true; 
  } 
 
  return false; 
} 
 
}  // namespace 
 
namespace time_internal { 
 
// The 'satq' argument indicates whether the quotient should saturate at the 
// bounds of int64_t.  If it does saturate, the difference will spill over to 
// the remainder.  If it does not saturate, the remainder remain accurate, 
// but the returned quotient will over/underflow int64_t and should not be used. 
int64_t IDivDuration(bool satq, const Duration num, const Duration den, 
                     Duration* rem) {
  int64_t q = 0; 
  if (IDivFastPath(num, den, &q, rem)) { 
    return q; 
  } 
 
  const bool num_neg = num < ZeroDuration(); 
  const bool den_neg = den < ZeroDuration(); 
  const bool quotient_neg = num_neg != den_neg; 
 
  if (time_internal::IsInfiniteDuration(num) || den == ZeroDuration()) { 
    *rem = num_neg ? -InfiniteDuration() : InfiniteDuration(); 
    return quotient_neg ? kint64min : kint64max; 
  } 
  if (time_internal::IsInfiniteDuration(den)) { 
    *rem = num; 
    return 0; 
  } 
 
  const uint128 a = MakeU128Ticks(num); 
  const uint128 b = MakeU128Ticks(den); 
  uint128 quotient128 = a / b; 
 
  if (satq) { 
    // Limits the quotient to the range of int64_t. 
    if (quotient128 > uint128(static_cast<uint64_t>(kint64max))) { 
      quotient128 = quotient_neg ? uint128(static_cast<uint64_t>(kint64min)) 
                                 : uint128(static_cast<uint64_t>(kint64max)); 
    } 
  } 
 
  const uint128 remainder128 = a - quotient128 * b; 
  *rem = MakeDurationFromU128(remainder128, num_neg); 
 
  if (!quotient_neg || quotient128 == 0) { 
    return Uint128Low64(quotient128) & kint64max; 
  } 
  // The quotient needs to be negated, but we need to carefully handle 
  // quotient128s with the top bit on. 
  return -static_cast<int64_t>(Uint128Low64(quotient128 - 1) & kint64max) - 1; 
} 
 
}  // namespace time_internal 
 
// 
// Additive operators. 
// 
 
Duration& Duration::operator+=(Duration rhs) { 
  if (time_internal::IsInfiniteDuration(*this)) return *this; 
  if (time_internal::IsInfiniteDuration(rhs)) return *this = rhs; 
  const int64_t orig_rep_hi = rep_hi_; 
  rep_hi_ = 
      DecodeTwosComp(EncodeTwosComp(rep_hi_) + EncodeTwosComp(rhs.rep_hi_)); 
  if (rep_lo_ >= kTicksPerSecond - rhs.rep_lo_) { 
    rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_) + 1); 
    rep_lo_ -= kTicksPerSecond; 
  } 
  rep_lo_ += rhs.rep_lo_; 
  if (rhs.rep_hi_ < 0 ? rep_hi_ > orig_rep_hi : rep_hi_ < orig_rep_hi) { 
    return *this = rhs.rep_hi_ < 0 ? -InfiniteDuration() : InfiniteDuration(); 
  } 
  return *this; 
} 
 
Duration& Duration::operator-=(Duration rhs) { 
  if (time_internal::IsInfiniteDuration(*this)) return *this; 
  if (time_internal::IsInfiniteDuration(rhs)) { 
    return *this = rhs.rep_hi_ >= 0 ? -InfiniteDuration() : InfiniteDuration(); 
  } 
  const int64_t orig_rep_hi = rep_hi_; 
  rep_hi_ = 
      DecodeTwosComp(EncodeTwosComp(rep_hi_) - EncodeTwosComp(rhs.rep_hi_)); 
  if (rep_lo_ < rhs.rep_lo_) { 
    rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_) - 1); 
    rep_lo_ += kTicksPerSecond; 
  } 
  rep_lo_ -= rhs.rep_lo_; 
  if (rhs.rep_hi_ < 0 ? rep_hi_ < orig_rep_hi : rep_hi_ > orig_rep_hi) { 
    return *this = rhs.rep_hi_ >= 0 ? -InfiniteDuration() : InfiniteDuration(); 
  } 
  return *this; 
} 
 
// 
// Multiplicative operators. 
// 
 
Duration& Duration::operator*=(int64_t r) { 
  if (time_internal::IsInfiniteDuration(*this)) { 
    const bool is_neg = (r < 0) != (rep_hi_ < 0); 
    return *this = is_neg ? -InfiniteDuration() : InfiniteDuration(); 
  } 
  return *this = ScaleFixed<SafeMultiply>(*this, r); 
} 
 
Duration& Duration::operator*=(double r) { 
  if (time_internal::IsInfiniteDuration(*this) || !IsFinite(r)) { 
    const bool is_neg = (std::signbit(r) != 0) != (rep_hi_ < 0); 
    return *this = is_neg ? -InfiniteDuration() : InfiniteDuration(); 
  } 
  return *this = ScaleDouble<std::multiplies>(*this, r); 
} 
 
Duration& Duration::operator/=(int64_t r) { 
  if (time_internal::IsInfiniteDuration(*this) || r == 0) { 
    const bool is_neg = (r < 0) != (rep_hi_ < 0); 
    return *this = is_neg ? -InfiniteDuration() : InfiniteDuration(); 
  } 
  return *this = ScaleFixed<std::divides>(*this, r); 
} 
 
Duration& Duration::operator/=(double r) { 
  if (time_internal::IsInfiniteDuration(*this) || !IsValidDivisor(r)) { 
    const bool is_neg = (std::signbit(r) != 0) != (rep_hi_ < 0); 
    return *this = is_neg ? -InfiniteDuration() : InfiniteDuration(); 
  } 
  return *this = ScaleDouble<std::divides>(*this, r); 
} 
 
Duration& Duration::operator%=(Duration rhs) { 
  time_internal::IDivDuration(false, *this, rhs, this); 
  return *this; 
} 
 
double FDivDuration(Duration num, Duration den) { 
  // Arithmetic with infinity is sticky. 
  if (time_internal::IsInfiniteDuration(num) || den == ZeroDuration()) { 
    return (num < ZeroDuration()) == (den < ZeroDuration()) 
               ? std::numeric_limits<double>::infinity() 
               : -std::numeric_limits<double>::infinity(); 
  } 
  if (time_internal::IsInfiniteDuration(den)) return 0.0; 
 
  double a = 
      static_cast<double>(time_internal::GetRepHi(num)) * kTicksPerSecond + 
      time_internal::GetRepLo(num); 
  double b = 
      static_cast<double>(time_internal::GetRepHi(den)) * kTicksPerSecond + 
      time_internal::GetRepLo(den); 
  return a / b; 
} 
 
// 
// Trunc/Floor/Ceil. 
// 
 
Duration Trunc(Duration d, Duration unit) { 
  return d - (d % unit); 
} 
 
Duration Floor(const Duration d, const Duration unit) { 
  const y_absl::Duration td = Trunc(d, unit);
  return td <= d ? td : td - AbsDuration(unit); 
} 
 
Duration Ceil(const Duration d, const Duration unit) { 
  const y_absl::Duration td = Trunc(d, unit);
  return td >= d ? td : td + AbsDuration(unit); 
} 
 
// 
// Factory functions. 
// 
 
Duration DurationFromTimespec(timespec ts) { 
  if (static_cast<uint64_t>(ts.tv_nsec) < 1000 * 1000 * 1000) { 
    int64_t ticks = ts.tv_nsec * kTicksPerNanosecond; 
    return time_internal::MakeDuration(ts.tv_sec, ticks); 
  } 
  return Seconds(ts.tv_sec) + Nanoseconds(ts.tv_nsec); 
} 
 
Duration DurationFromTimeval(timeval tv) { 
  if (static_cast<uint64_t>(tv.tv_usec) < 1000 * 1000) { 
    int64_t ticks = tv.tv_usec * 1000 * kTicksPerNanosecond; 
    return time_internal::MakeDuration(tv.tv_sec, ticks); 
  } 
  return Seconds(tv.tv_sec) + Microseconds(tv.tv_usec); 
} 
 
// 
// Conversion to other duration types. 
// 
 
int64_t ToInt64Nanoseconds(Duration d) { 
  if (time_internal::GetRepHi(d) >= 0 && 
      time_internal::GetRepHi(d) >> 33 == 0) { 
    return (time_internal::GetRepHi(d) * 1000 * 1000 * 1000) + 
           (time_internal::GetRepLo(d) / kTicksPerNanosecond); 
  } 
  return d / Nanoseconds(1); 
} 
int64_t ToInt64Microseconds(Duration d) { 
  if (time_internal::GetRepHi(d) >= 0 && 
      time_internal::GetRepHi(d) >> 43 == 0) { 
    return (time_internal::GetRepHi(d) * 1000 * 1000) + 
           (time_internal::GetRepLo(d) / (kTicksPerNanosecond * 1000)); 
  } 
  return d / Microseconds(1); 
} 
int64_t ToInt64Milliseconds(Duration d) { 
  if (time_internal::GetRepHi(d) >= 0 && 
      time_internal::GetRepHi(d) >> 53 == 0) { 
    return (time_internal::GetRepHi(d) * 1000) + 
           (time_internal::GetRepLo(d) / (kTicksPerNanosecond * 1000 * 1000)); 
  } 
  return d / Milliseconds(1); 
} 
int64_t ToInt64Seconds(Duration d) { 
  int64_t hi = time_internal::GetRepHi(d); 
  if (time_internal::IsInfiniteDuration(d)) return hi; 
  if (hi < 0 && time_internal::GetRepLo(d) != 0) ++hi; 
  return hi; 
} 
int64_t ToInt64Minutes(Duration d) { 
  int64_t hi = time_internal::GetRepHi(d); 
  if (time_internal::IsInfiniteDuration(d)) return hi; 
  if (hi < 0 && time_internal::GetRepLo(d) != 0) ++hi; 
  return hi / 60; 
} 
int64_t ToInt64Hours(Duration d) { 
  int64_t hi = time_internal::GetRepHi(d); 
  if (time_internal::IsInfiniteDuration(d)) return hi; 
  if (hi < 0 && time_internal::GetRepLo(d) != 0) ++hi; 
  return hi / (60 * 60); 
} 
 
double ToDoubleNanoseconds(Duration d) { 
  return FDivDuration(d, Nanoseconds(1)); 
} 
double ToDoubleMicroseconds(Duration d) { 
  return FDivDuration(d, Microseconds(1)); 
} 
double ToDoubleMilliseconds(Duration d) { 
  return FDivDuration(d, Milliseconds(1)); 
} 
double ToDoubleSeconds(Duration d) { 
  return FDivDuration(d, Seconds(1)); 
} 
double ToDoubleMinutes(Duration d) { 
  return FDivDuration(d, Minutes(1)); 
} 
double ToDoubleHours(Duration d) { 
  return FDivDuration(d, Hours(1)); 
} 
 
timespec ToTimespec(Duration d) { 
  timespec ts; 
  if (!time_internal::IsInfiniteDuration(d)) { 
    int64_t rep_hi = time_internal::GetRepHi(d); 
    uint32_t rep_lo = time_internal::GetRepLo(d); 
    if (rep_hi < 0) { 
      // Tweak the fields so that unsigned division of rep_lo 
      // maps to truncation (towards zero) for the timespec. 
      rep_lo += kTicksPerNanosecond - 1; 
      if (rep_lo >= kTicksPerSecond) { 
        rep_hi += 1; 
        rep_lo -= kTicksPerSecond; 
      } 
    } 
    ts.tv_sec = rep_hi; 
    if (ts.tv_sec == rep_hi) {  // no time_t narrowing 
      ts.tv_nsec = rep_lo / kTicksPerNanosecond; 
      return ts; 
    } 
  } 
  if (d >= ZeroDuration()) { 
    ts.tv_sec = std::numeric_limits<time_t>::max(); 
    ts.tv_nsec = 1000 * 1000 * 1000 - 1; 
  } else { 
    ts.tv_sec = std::numeric_limits<time_t>::min(); 
    ts.tv_nsec = 0; 
  } 
  return ts; 
} 
 
timeval ToTimeval(Duration d) { 
  timeval tv; 
  timespec ts = ToTimespec(d); 
  if (ts.tv_sec < 0) { 
    // Tweak the fields so that positive division of tv_nsec 
    // maps to truncation (towards zero) for the timeval. 
    ts.tv_nsec += 1000 - 1; 
    if (ts.tv_nsec >= 1000 * 1000 * 1000) { 
      ts.tv_sec += 1; 
      ts.tv_nsec -= 1000 * 1000 * 1000; 
    } 
  } 
  tv.tv_sec = ts.tv_sec; 
  if (tv.tv_sec != ts.tv_sec) {  // narrowing 
    if (ts.tv_sec < 0) { 
      tv.tv_sec = std::numeric_limits<decltype(tv.tv_sec)>::min(); 
      tv.tv_usec = 0; 
    } else { 
      tv.tv_sec = std::numeric_limits<decltype(tv.tv_sec)>::max(); 
      tv.tv_usec = 1000 * 1000 - 1; 
    } 
    return tv; 
  } 
  tv.tv_usec = static_cast<int>(ts.tv_nsec / 1000);  // suseconds_t 
  return tv; 
} 
 
std::chrono::nanoseconds ToChronoNanoseconds(Duration d) { 
  return time_internal::ToChronoDuration<std::chrono::nanoseconds>(d); 
} 
std::chrono::microseconds ToChronoMicroseconds(Duration d) { 
  return time_internal::ToChronoDuration<std::chrono::microseconds>(d); 
} 
std::chrono::milliseconds ToChronoMilliseconds(Duration d) { 
  return time_internal::ToChronoDuration<std::chrono::milliseconds>(d); 
} 
std::chrono::seconds ToChronoSeconds(Duration d) { 
  return time_internal::ToChronoDuration<std::chrono::seconds>(d); 
} 
std::chrono::minutes ToChronoMinutes(Duration d) { 
  return time_internal::ToChronoDuration<std::chrono::minutes>(d); 
} 
std::chrono::hours ToChronoHours(Duration d) { 
  return time_internal::ToChronoDuration<std::chrono::hours>(d); 
} 
 
// 
// To/From string formatting. 
// 
 
namespace { 
 
// Formats a positive 64-bit integer in the given field width.  Note that 
// it is up to the caller of Format64() to ensure that there is sufficient 
// space before ep to hold the conversion. 
char* Format64(char* ep, int width, int64_t v) { 
  do { 
    --width; 
    *--ep = '0' + (v % 10);  // contiguous digits 
  } while (v /= 10); 
  while (--width >= 0) *--ep = '0';  // zero pad 
  return ep; 
} 
 
// Helpers for FormatDuration() that format 'n' and append it to 'out' 
// followed by the given 'unit'.  If 'n' formats to "0", nothing is 
// appended (not even the unit). 
 
// A type that encapsulates how to display a value of a particular unit. For 
// values that are displayed with fractional parts, the precision indicates 
// where to round the value. The precision varies with the display unit because 
// a Duration can hold only quarters of a nanosecond, so displaying information 
// beyond that is just noise. 
// 
// For example, a microsecond value of 42.00025xxxxx should not display beyond 5 
// fractional digits, because it is in the noise of what a Duration can 
// represent. 
struct DisplayUnit { 
  y_absl::string_view abbr;
  int prec; 
  double pow10; 
}; 
ABSL_CONST_INIT const DisplayUnit kDisplayNano = {"ns", 2, 1e2};
ABSL_CONST_INIT const DisplayUnit kDisplayMicro = {"us", 5, 1e5};
ABSL_CONST_INIT const DisplayUnit kDisplayMilli = {"ms", 8, 1e8};
ABSL_CONST_INIT const DisplayUnit kDisplaySec = {"s", 11, 1e11};
ABSL_CONST_INIT const DisplayUnit kDisplayMin = {"m", -1, 0.0};  // prec ignored
ABSL_CONST_INIT const DisplayUnit kDisplayHour = {"h", -1,
                                                  0.0};  // prec ignored
 
void AppendNumberUnit(TString* out, int64_t n, DisplayUnit unit) {
  char buf[sizeof("2562047788015216")];  // hours in max duration 
  char* const ep = buf + sizeof(buf); 
  char* bp = Format64(ep, 0, n); 
  if (*bp != '0' || bp + 1 != ep) { 
    out->append(bp, ep - bp); 
    out->append(unit.abbr.data(), unit.abbr.size());
  } 
} 
 
// Note: unit.prec is limited to double's digits10 value (typically 15) so it 
// always fits in buf[]. 
void AppendNumberUnit(TString* out, double n, DisplayUnit unit) {
  constexpr int kBufferSize = std::numeric_limits<double>::digits10;
  const int prec = std::min(kBufferSize, unit.prec);
  char buf[kBufferSize];  // also large enough to hold integer part
  char* ep = buf + sizeof(buf); 
  double d = 0; 
  int64_t frac_part = Round(std::modf(n, &d) * unit.pow10); 
  int64_t int_part = d; 
  if (int_part != 0 || frac_part != 0) { 
    char* bp = Format64(ep, 0, int_part);  // always < 1000 
    out->append(bp, ep - bp); 
    if (frac_part != 0) { 
      out->push_back('.'); 
      bp = Format64(ep, prec, frac_part); 
      while (ep[-1] == '0') --ep; 
      out->append(bp, ep - bp); 
    } 
    out->append(unit.abbr.data(), unit.abbr.size());
  } 
} 
 
}  // namespace 
 
// From Go's doc at https://golang.org/pkg/time/#Duration.String 
//   [FormatDuration] returns a string representing the duration in the 
//   form "72h3m0.5s". Leading zero units are omitted.  As a special 
//   case, durations less than one second format use a smaller unit 
//   (milli-, micro-, or nanoseconds) to ensure that the leading digit 
//   is non-zero.
// Unlike Go, we format the zero duration as 0, with no unit.
TString FormatDuration(Duration d) {
  const Duration min_duration = Seconds(kint64min); 
  if (d == min_duration) { 
    // Avoid needing to negate kint64min by directly returning what the 
    // following code should produce in that case. 
    return "-2562047788015215h30m8s"; 
  } 
  TString s;
  if (d < ZeroDuration()) { 
    s.append("-"); 
    d = -d; 
  } 
  if (d == InfiniteDuration()) { 
    s.append("inf"); 
  } else if (d < Seconds(1)) { 
    // Special case for durations with a magnitude < 1 second.  The duration 
    // is printed as a fraction of a single unit, e.g., "1.2ms". 
    if (d < Microseconds(1)) { 
      AppendNumberUnit(&s, FDivDuration(d, Nanoseconds(1)), kDisplayNano); 
    } else if (d < Milliseconds(1)) { 
      AppendNumberUnit(&s, FDivDuration(d, Microseconds(1)), kDisplayMicro); 
    } else { 
      AppendNumberUnit(&s, FDivDuration(d, Milliseconds(1)), kDisplayMilli); 
    } 
  } else { 
    AppendNumberUnit(&s, IDivDuration(d, Hours(1), &d), kDisplayHour); 
    AppendNumberUnit(&s, IDivDuration(d, Minutes(1), &d), kDisplayMin); 
    AppendNumberUnit(&s, FDivDuration(d, Seconds(1)), kDisplaySec); 
  } 
  if (s.empty() || s == "-") { 
    s = "0"; 
  } 
  return s; 
} 
 
namespace { 
 
// A helper for ParseDuration() that parses a leading number from the given 
// string and stores the result in *int_part/*frac_part/*frac_scale.  The 
// given string pointer is modified to point to the first unconsumed char. 
bool ConsumeDurationNumber(const char** dpp, const char* ep, int64_t* int_part,
                           int64_t* frac_part, int64_t* frac_scale) { 
  *int_part = 0; 
  *frac_part = 0; 
  *frac_scale = 1;  // invariant: *frac_part < *frac_scale 
  const char* start = *dpp; 
  for (; *dpp != ep; *dpp += 1) {
    const int d = **dpp - '0';  // contiguous digits 
    if (d < 0 || 10 <= d) break;

    if (*int_part > kint64max / 10) return false; 
    *int_part *= 10; 
    if (*int_part > kint64max - d) return false; 
    *int_part += d; 
  } 
  const bool int_part_empty = (*dpp == start); 
  if (*dpp == ep || **dpp != '.') return !int_part_empty;

  for (*dpp += 1; *dpp != ep; *dpp += 1) {
    const int d = **dpp - '0';  // contiguous digits 
    if (d < 0 || 10 <= d) break;
    if (*frac_scale <= kint64max / 10) { 
      *frac_part *= 10; 
      *frac_part += d; 
      *frac_scale *= 10; 
    } 
  } 
  return !int_part_empty || *frac_scale != 1; 
} 
 
// A helper for ParseDuration() that parses a leading unit designator (e.g., 
// ns, us, ms, s, m, h) from the given string and stores the resulting unit 
// in "*unit".  The given string pointer is modified to point to the first 
// unconsumed char. 
bool ConsumeDurationUnit(const char** start, const char* end, Duration* unit) {
  size_t size = end - *start;
  switch (size) {
    case 0:
      return false;
    default:
      switch (**start) {
        case 'n':
          if (*(*start + 1) == 's') {
            *start += 2;
            *unit = Nanoseconds(1);
            return true;
          }
          break;
        case 'u':
          if (*(*start + 1) == 's') {
            *start += 2;
            *unit = Microseconds(1);
            return true;
          }
          break;
        case 'm':
          if (*(*start + 1) == 's') {
            *start += 2;
            *unit = Milliseconds(1);
            return true;
          }
          break;
        default:
          break;
      }
      ABSL_FALLTHROUGH_INTENDED;
    case 1:
      switch (**start) {
        case 's':
          *unit = Seconds(1);
          *start += 1;
          return true;
        case 'm':
          *unit = Minutes(1);
          *start += 1;
          return true;
        case 'h':
          *unit = Hours(1);
          *start += 1;
          return true;
        default:
          return false;
      }
  } 
} 
 
}  // namespace 
 
// From Go's doc at https://golang.org/pkg/time/#ParseDuration 
//   [ParseDuration] parses a duration string. A duration string is 
//   a possibly signed sequence of decimal numbers, each with optional 
//   fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m". 
//   Valid time units are "ns", "us" "ms", "s", "m", "h". 
bool ParseDuration(y_absl::string_view dur_sv, Duration* d) {
  int sign = 1; 
  if (y_absl::ConsumePrefix(&dur_sv, "-")) {
    sign = -1;
  } else {
    y_absl::ConsumePrefix(&dur_sv, "+");
  } 
  if (dur_sv.empty()) return false;
 
  // Special case for a string of "0".
  if (dur_sv == "0") {
    *d = ZeroDuration(); 
    return true; 
  } 
 
  if (dur_sv == "inf") {
    *d = sign * InfiniteDuration(); 
    return true; 
  } 
 
  const char* start = dur_sv.data();
  const char* end = start + dur_sv.size();

  Duration dur; 
  while (start != end) {
    int64_t int_part; 
    int64_t frac_part; 
    int64_t frac_scale; 
    Duration unit; 
    if (!ConsumeDurationNumber(&start, end, &int_part, &frac_part,
                               &frac_scale) ||
        !ConsumeDurationUnit(&start, end, &unit)) {
      return false; 
    } 
    if (int_part != 0) dur += sign * int_part * unit; 
    if (frac_part != 0) dur += sign * frac_part * unit / frac_scale; 
  } 
  *d = dur; 
  return true; 
} 
 
bool AbslParseFlag(y_absl::string_view text, Duration* dst, TString*) {
  return ParseDuration(text, dst);
} 
 
TString AbslUnparseFlag(Duration d) { return FormatDuration(d); }
bool ParseFlag(const TString& text, Duration* dst, TString* ) {
  return ParseDuration(text, dst); 
} 
 
TString UnparseFlag(Duration d) { return FormatDuration(d); }
 
ABSL_NAMESPACE_END
}  // namespace y_absl