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diff --git a/absl/time/time.h b/absl/time/time.h new file mode 100644 index 000000000000..302c76037e6f --- /dev/null +++ b/absl/time/time.h @@ -0,0 +1,1181 @@ +// 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 +// +// http://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. +// +// ----------------------------------------------------------------------------- +// File: time.h +// ----------------------------------------------------------------------------- +// +// This header file defines abstractions for computing with absolute points +// in time, durations of time, and formatting and parsing time within a given +// time zone. The following abstractions are defined: +// +// * `absl::Time` defines an absolute, specific instance in time +// * `absl::Duration` defines a signed, fixed-length span of time +// * `absl::TimeZone` defines geopolitical time zone regions (as collected +// within the IANA Time Zone database (https://www.iana.org/time-zones)). +// +// Example: +// +// absl::TimeZone nyc; +// +// // LoadTimeZone may fail so it's always better to check for success. +// if (!absl::LoadTimeZone("America/New_York", &nyc)) { +// // handle error case +// } +// +// // My flight leaves NYC on Jan 2, 2017 at 03:04:05 +// absl::Time takeoff = absl::FromDateTime(2017, 1, 2, 3, 4, 5, nyc); +// absl::Duration flight_duration = absl::Hours(21) + absl::Minutes(35); +// absl::Time landing = takeoff + flight_duration; +// +// absl::TimeZone syd; +// if (!absl::LoadTimeZone("Australia/Sydney", &syd)) { +// // handle error case +// } +// std::string s = absl::FormatTime( +// "My flight will land in Sydney on %Y-%m-%d at %H:%M:%S", +// landing, syd); +// +#ifndef ABSL_TIME_TIME_H_ +#define ABSL_TIME_TIME_H_ + +#if !defined(_WIN32) +#include <sys/time.h> +#else +#include <winsock2.h> +#endif +#include <chrono> // NOLINT(build/c++11) +#include <cstdint> +#include <ctime> +#include <ostream> +#include <string> +#include <type_traits> +#include <utility> + +#include "absl/base/port.h" // Needed for string vs std::string +#include "cctz/time_zone.h" + +namespace absl { + +class Duration; // Defined below +class Time; // Defined below +class TimeZone; // Defined below + +namespace time_internal { +int64_t IDivDuration(bool satq, Duration num, Duration den, Duration* rem); +constexpr Time FromUnixDuration(Duration d); +constexpr Duration ToUnixDuration(Time t); +constexpr int64_t GetRepHi(Duration d); +constexpr uint32_t GetRepLo(Duration d); +constexpr Duration MakeDuration(int64_t hi, uint32_t lo); +constexpr Duration MakeDuration(int64_t hi, int64_t lo); +constexpr int64_t kTicksPerNanosecond = 4; +constexpr int64_t kTicksPerSecond = 1000 * 1000 * 1000 * kTicksPerNanosecond; +template <typename T> +using IsFloatingPoint = + typename std::enable_if<std::is_floating_point<T>::value, int>::type; +} // namespace time_internal + +// Duration +// +// The `absl::Duration` class represents a signed, fixed-length span of time. +// A `Duration` is generated using a unit-specific factory function, or is +// the result of subtracting one `absl::Time` from another. Durations behave +// like unit-safe integers and they support all the natural integer-like +// arithmetic operations. Arithmetic overflows and saturates at +/- infinity. +// `Duration` should be passed by value rather than const reference. +// +// Factory functions `Nanoseconds()`, `Microseconds()`, `Milliseconds()`, +// `Seconds()`, `Minutes()`, `Hours()` and `InfiniteDuration()` allow for +// creation of constexpr `Duration` values +// +// Examples: +// +// constexpr absl::Duration ten_ns = absl::Nanoseconds(10); +// constexpr absl::Duration min = absl::Minutes(1); +// constexpr absl::Duration hour = absl::Hours(1); +// absl::Duration dur = 60 * min; // dur == hour +// absl::Duration half_sec = absl::Milliseconds(500); +// absl::Duration quarter_sec = 0.25 * absl::Seconds(1); +// +// `Duration` values can be easily converted to an integral number of units +// using the division operator. +// +// Example: +// +// constexpr absl::Duration dur = absl::Milliseconds(1500); +// int64_t ns = dur / absl::Nanoseconds(1); // ns == 1500000000 +// int64_t ms = dur / absl::Milliseconds(1); // ms == 1500 +// int64_t sec = dur / absl::Seconds(1); // sec == 1 (subseconds truncated) +// int64_t min = dur / absl::Minutes(1); // min == 0 +// +// See the `IDivDuration()` and `FDivDuration()` functions below for details on +// how to access the fractional parts of the quotient. +// +// Alternatively, conversions can be performed using helpers such as +// `ToInt64Microseconds()` and `ToDoubleSeconds()`. +class Duration { + public: + // Value semantics. + constexpr Duration() : rep_hi_(0), rep_lo_(0) {} // zero-length duration + + // Compound assignment operators. + Duration& operator+=(Duration d); + Duration& operator-=(Duration d); + Duration& operator*=(int64_t r); + Duration& operator*=(double r); + Duration& operator/=(int64_t r); + Duration& operator/=(double r); + Duration& operator%=(Duration rhs); + + // Overloads that forward to either the int64_t or double overloads above. + template <typename T> + Duration& operator*=(T r) { + int64_t x = r; + return *this *= x; + } + template <typename T> + Duration& operator/=(T r) { + int64_t x = r; + return *this /= x; + } + Duration& operator*=(float r) { return *this *= static_cast<double>(r); } + Duration& operator/=(float r) { return *this /= static_cast<double>(r); } + + private: + friend constexpr int64_t time_internal::GetRepHi(Duration d); + friend constexpr uint32_t time_internal::GetRepLo(Duration d); + friend constexpr Duration time_internal::MakeDuration(int64_t hi, + uint32_t lo); + constexpr Duration(int64_t hi, uint32_t lo) : rep_hi_(hi), rep_lo_(lo) {} + int64_t rep_hi_; + uint32_t rep_lo_; +}; + +// Relational Operators +constexpr bool operator<(Duration lhs, Duration rhs); +constexpr bool operator>(Duration lhs, Duration rhs) { return rhs < lhs; } +constexpr bool operator>=(Duration lhs, Duration rhs) { return !(lhs < rhs); } +constexpr bool operator<=(Duration lhs, Duration rhs) { return !(rhs < lhs); } +constexpr bool operator==(Duration lhs, Duration rhs); +constexpr bool operator!=(Duration lhs, Duration rhs) { return !(lhs == rhs); } + +// Additive Operators +constexpr Duration operator-(Duration d); +inline Duration operator+(Duration lhs, Duration rhs) { return lhs += rhs; } +inline Duration operator-(Duration lhs, Duration rhs) { return lhs -= rhs; } + +// Multiplicative Operators +template <typename T> +inline Duration operator*(Duration lhs, T rhs) { + return lhs *= rhs; +} +template <typename T> +inline Duration operator*(T lhs, Duration rhs) { + return rhs *= lhs; +} +template <typename T> +inline Duration operator/(Duration lhs, T rhs) { + return lhs /= rhs; +} +inline int64_t operator/(Duration lhs, Duration rhs) { + return time_internal::IDivDuration(true, lhs, rhs, + &lhs); // trunc towards zero +} +inline Duration operator%(Duration lhs, Duration rhs) { return lhs %= rhs; } + +// IDivDuration() +// +// Divides a numerator `Duration` by a denominator `Duration`, returning the +// quotient and remainder. The remainder always has the same sign as the +// numerator. The returned quotient and remainder respect the identity: +// +// numerator = denominator * quotient + remainder +// +// Returned quotients are capped to the range of `int64_t`, with the difference +// spilling into the remainder to uphold the above identity. This means that the +// remainder returned could differ from the remainder returned by +// `Duration::operator%` for huge quotients. +// +// See also the notes on `InfiniteDuration()` below regarding the behavior of +// division involving zero and infinite durations. +// +// Example: +// +// constexpr absl::Duration a = +// absl::Seconds(std::numeric_limits<int64_t>::max()); // big +// constexpr absl::Duration b = absl::Nanoseconds(1); // small +// +// absl::Duration rem = a % b; +// // rem == absl::ZeroDuration() +// +// // Here, q would overflow int64_t, so rem accounts for the difference. +// int64_t q = absl::IDivDuration(a, b, &rem); +// // q == std::numeric_limits<int64_t>::max(), rem == a - b * q +inline int64_t IDivDuration(Duration num, Duration den, Duration* rem) { + return time_internal::IDivDuration(true, num, den, + rem); // trunc towards zero +} + +// FDivDuration() +// +// Divides a `Duration` numerator into a fractional number of units of a +// `Duration` denominator. +// +// See also the notes on `InfiniteDuration()` below regarding the behavior of +// division involving zero and infinite durations. +// +// Example: +// +// double d = absl::FDivDuration(absl::Milliseconds(1500), absl::Seconds(1)); +// // d == 1.5 +double FDivDuration(Duration num, Duration den); + +// ZeroDuration() +// +// Returns a zero-length duration. This function behaves just like the default +// constructor, but the name helps make the semantics clear at call sites. +constexpr Duration ZeroDuration() { return Duration(); } + +// AbsDuration() +// +// Returns the absolute value of a duration. +inline Duration AbsDuration(Duration d) { + return (d < ZeroDuration()) ? -d : d; +} + +// Trunc() +// +// Truncates a duration (toward zero) to a multiple of a non-zero unit. +// +// Example: +// +// absl::Duration d = absl::Nanoseconds(123456789); +// absl::Duration a = absl::Trunc(d, absl::Microseconds(1)); // 123456us +Duration Trunc(Duration d, Duration unit); + +// Floor() +// +// Floors a duration using the passed duration unit to its largest value not +// greater than the duration. +// +// Example: +// +// absl::Duration d = absl::Nanoseconds(123456789); +// absl::Duration b = absl::Floor(d, absl::Microseconds(1)); // 123456us +Duration Floor(Duration d, Duration unit); + +// Ceil() +// +// Returns the ceiling of a duration using the passed duration unit to its +// smallest value not less than the duration. +// +// Example: +// +// absl::Duration d = absl::Nanoseconds(123456789); +// absl::Duration c = absl::Ceil(d, absl::Microseconds(1)); // 123457us +Duration Ceil(Duration d, Duration unit); + +// Nanoseconds() +// Microseconds() +// Milliseconds() +// Seconds() +// Minutes +// Hours() +// +// Factory functions for constructing `Duration` values from an integral number +// of the unit indicated by the factory function's name. +// +// Note: no "Days()" factory function exists because "a day" is ambiguous. Civil +// days are not always 24 hours long, and a 24-hour duration often does not +// correspond with a civil day. If a 24-hour duration is needed, use +// `absl::Hours(24)`. +// +// +// Example: +// +// absl::Duration a = absl::Seconds(60); +// absl::Duration b = absl::Minutes(1); // b == a +constexpr Duration Nanoseconds(int64_t n); +constexpr Duration Microseconds(int64_t n); +constexpr Duration Milliseconds(int64_t n); +constexpr Duration Seconds(int64_t n); +constexpr Duration Minutes(int64_t n); +constexpr Duration Hours(int64_t n); + +// Factory overloads for constructing `Duration` values from a floating-point +// number of the unit indicated by the factory function's name. These functions +// exist for convenience, but they are not as efficient as the integral +// factories, which should be preferred. +// +// Example: +// auto a = absl::Seconds(1.5); // OK +// auto b = absl::Milliseconds(1500); // BETTER +template <typename T, time_internal::IsFloatingPoint<T> = 0> +Duration Nanoseconds(T n) { + return n * Nanoseconds(1); +} +template <typename T, time_internal::IsFloatingPoint<T> = 0> +Duration Microseconds(T n) { + return n * Microseconds(1); +} +template <typename T, time_internal::IsFloatingPoint<T> = 0> +Duration Milliseconds(T n) { + return n * Milliseconds(1); +} +template <typename T, time_internal::IsFloatingPoint<T> = 0> +Duration Seconds(T n) { + return n * Seconds(1); +} +template <typename T, time_internal::IsFloatingPoint<T> = 0> +Duration Minutes(T n) { + return n * Minutes(1); +} +template <typename T, time_internal::IsFloatingPoint<T> = 0> +Duration Hours(T n) { + return n * Hours(1); +} + +// ToInt64Nanoseconds() +// ToInt64Microseconds() +// ToInt64Milliseconds() +// ToInt64Seconds() +// ToInt64Minutes() +// ToInt64Hours() +// +// Helper functions that convert a Duration to an integral count of the +// indicated unit. These functions are shorthand for the `IDivDuration()` +// function above; see its documentation for details about overflow, etc. +// +// Example: +// +// absl::Duration d = absl::Milliseconds(1500); +// int64_t isec = ToInt64Seconds(d); // isec == 1 +int64_t ToInt64Nanoseconds(Duration d); +int64_t ToInt64Microseconds(Duration d); +int64_t ToInt64Milliseconds(Duration d); +int64_t ToInt64Seconds(Duration d); +int64_t ToInt64Minutes(Duration d); +int64_t ToInt64Hours(Duration d); + +// ToDoubleNanoSeconds() +// ToDoubleMicroseconds() +// ToDoubleMilliseconds() +// ToDoubleSeconds() +// ToDoubleMinutes() +// ToDoubleHours +// +// Helper functions that convert a Duration to a floating point count of the +// indicated unit. These functions are shorthand for the `FDivDuration()` +// function above; see its documentation for details about overflow, etc. +// +// Example: +// +// absl::Duration d = absl::Milliseconds(1500); +// double dsec = ToDoubleSeconds(d); // dsec == 1.5 +double ToDoubleNanoseconds(Duration d); +double ToDoubleMicroseconds(Duration d); +double ToDoubleMilliseconds(Duration d); +double ToDoubleSeconds(Duration d); +double ToDoubleMinutes(Duration d); +double ToDoubleHours(Duration d); + +// InfiniteDuration() +// +// Returns an infinite `Duration`. To get a `Duration` representing negative +// infinity, use `-InfiniteDuration()`. +// +// Duration arithmetic overflows to +/- infinity and saturates. In general, +// arithmetic with `Duration` infinities is similar to IEEE 754 infinities +// except where IEEE 754 NaN would be involved, in which case +/- +// `InfiniteDuration()` is used in place of a "nan" Duration. +// +// Examples: +// +// constexpr absl::Duration inf = absl::InfiniteDuration(); +// const absl::Duration d = ... any finite duration ... +// +// inf == inf + inf +// inf == inf + d +// inf == inf - inf +// -inf == d - inf +// +// inf == d * 1e100 +// inf == inf / 2 +// 0 == d / inf +// INT64_MAX == inf / d +// +// // Division by zero returns infinity, or INT64_MIN/MAX where appropriate. +// inf == d / 0 +// INT64_MAX == d / absl::ZeroDuration() +// +// The examples involving the `/` operator above also apply to `IDivDuration()` +// and `FDivDuration()`. +constexpr Duration InfiniteDuration(); + +// FormatDuration() +// +// Returns a std::string representing the duration in the form "72h3m0.5s". +// Returns "inf" or "-inf" for +/- `InfiniteDuration()`. +std::string FormatDuration(Duration d); + +// Output stream operator. +inline std::ostream& operator<<(std::ostream& os, Duration d) { + return os << FormatDuration(d); +} + +// ParseDuration() +// +// Parses a duration std::string consisting of a possibly signed sequence +// of decimal numbers, each with an optional fractional part and a +// unit suffix. The valid suffixes are "ns", "us" "ms", "s", "m", +// and "h". Simple examples include "300ms", "-1.5h", and "2h45m". +// Parses "inf" and "-inf" as +/- `InfiniteDuration()`. +bool ParseDuration(const std::string& dur_string, Duration* d); + +// Flag Support +// TODO(b/63899288) copybara strip once dependencies are removed. + +// ParseFlag() +// +bool ParseFlag(const std::string& text, Duration* dst, std::string* error); + +// UnparseFlag() +// +std::string UnparseFlag(Duration d); + +// Time +// +// An `absl::Time` represents a specific instant in time. Arithmetic operators +// are provided for naturally expressing time calculations. Instances are +// created using `absl::Now()` and the `absl::From*()` factory functions that +// accept the gamut of other time representations. Formatting and parsing +// functions are provided for conversion to and from strings. `absl::Time` +// should be passed by value rather than const reference. +// +// `absl::Time` assumes there are 60 seconds in a minute, which means the +// underlying time scales must be "smeared" to eliminate leap seconds. +// POSIX, for example, legislates that a `time_t` value of `536457599` shall +// correspond to "1986-12-31 23:59:59 +0000". +// +// +// Even though `absl::Time` supports a wide range of timestamps, exercise +// caution when using values in the distant past. `absl::Time` uses the +// Proleptic Gregorian calendar, which extends the Gregorian calendar backward +// to dates before its introduction in 1582. +// See https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar +// for more information. Use the ICU calendar classes to convert a date in +// some other calendar (http://userguide.icu-project.org/datetime/calendar). +// +// Similarly, standardized time zones are a reasonably recent innovation, with +// the Greenwich prime meridian being established in 1884. The TZ database +// itself does not profess accurate offsets for timestamps prior to 1970. The +// breakdown of future timestamps is subject to the whim of regional +// governments. +// +// The `absl::Time` class represents an instant in time as a count of clock +// ticks of some granularity (resolution) from some starting point (epoch). +// +// +// `absl::Time` uses a resolution that is high enough to avoid loss in +// precision, and a range that is wide enough to avoid overflow, when +// converting between tick counts in most Google time scales (i.e., precision +// of at least one nanosecond, and range +/-100 billion years). Conversions +// between the time scales are performed by truncating (towards negative +// infinity) to the nearest representable point. +// +// Examples: +// +// absl::Time t1 = ...; +// absl::Time t2 = t1 + absl::Minutes(2); +// absl::Duration d = t2 - t1; // == absl::Minutes(2) +// absl::Time::Breakdown bd = t1.In(absl::LocalTimeZone()); +// +class Time { + public: + // Value semantics. + + // Returns the Unix epoch. However, those reading your code may not know + // or expect the Unix epoch as the default value, so make your code more + // readable by explicitly initializing all instances before use. + // + // Example: + // absl::Time t = absl::UnixEpoch(); + // absl::Time t = absl::Now(); + // absl::Time t = absl::TimeFromTimeval(tv); + // absl::Time t = absl::InfinitePast(); + constexpr Time() {} + + // Assignment operators. + Time& operator+=(Duration d) { rep_ += d; return *this; } + Time& operator-=(Duration d) { rep_ -= d; return *this; } + + // Time::Breakdown + // + // The calendar and wall-clock (aka "civil time") components of a + // `absl::Time` in a certain `absl::TimeZone`. This struct is not + // intended to represent an instant in time. So, rather than passing + // a `Time::Breakdown` to a function, pass an `absl::Time` and an + // `absl::TimeZone`. + struct Breakdown { + int64_t year; // year (e.g., 2013) + int month; // month of year [1:12] + int day; // day of month [1:31] + int hour; // hour of day [0:23] + int minute; // minute of hour [0:59] + int second; // second of minute [0:59] + Duration subsecond; // [Seconds(0):Seconds(1)) if finite + int weekday; // 1==Mon, ..., 7=Sun + int yearday; // day of year [1:366] + + // Note: The following fields exist for backward compatibility + // with older APIs. Accessing these fields directly is a sign of + // imprudent logic in the calling code. Modern time-related code + // should only access this data indirectly by way of FormatTime(). + // These fields are undefined for InfiniteFuture() and InfinitePast(). + int offset; // seconds east of UTC + bool is_dst; // is offset non-standard? + const char* zone_abbr; // time-zone abbreviation (e.g., "PST") + }; + + // Time::In() + // + // Returns the breakdown of this instant in the given TimeZone. + Breakdown In(TimeZone tz) const; + + private: + friend constexpr Time time_internal::FromUnixDuration(Duration d); + friend constexpr Duration time_internal::ToUnixDuration(Time t); + friend constexpr bool operator<(Time lhs, Time rhs); + friend constexpr bool operator==(Time lhs, Time rhs); + friend Duration operator-(Time lhs, Time rhs); + friend constexpr Time UniversalEpoch(); + friend constexpr Time InfiniteFuture(); + friend constexpr Time InfinitePast(); + constexpr explicit Time(Duration rep) : rep_(rep) {} + Duration rep_; +}; + +// Relational Operators +constexpr bool operator<(Time lhs, Time rhs) { return lhs.rep_ < rhs.rep_; } +constexpr bool operator>(Time lhs, Time rhs) { return rhs < lhs; } +constexpr bool operator>=(Time lhs, Time rhs) { return !(lhs < rhs); } +constexpr bool operator<=(Time lhs, Time rhs) { return !(rhs < lhs); } +constexpr bool operator==(Time lhs, Time rhs) { return lhs.rep_ == rhs.rep_; } +constexpr bool operator!=(Time lhs, Time rhs) { return !(lhs == rhs); } + +// Additive Operators +inline Time operator+(Time lhs, Duration rhs) { return lhs += rhs; } +inline Time operator+(Duration lhs, Time rhs) { return rhs += lhs; } +inline Time operator-(Time lhs, Duration rhs) { return lhs -= rhs; } +inline Duration operator-(Time lhs, Time rhs) { return lhs.rep_ - rhs.rep_; } + +// UnixEpoch() +// +// Returns the `absl::Time` representing "1970-01-01 00:00:00.0 +0000". +constexpr Time UnixEpoch() { + return Time(); +} + +// UniversalEpoch() +// +// Returns the `absl::Time` representing "0001-01-01 00:00:00.0 +0000", the +// epoch of the ICU Universal Time Scale. +constexpr Time UniversalEpoch() { + // 719162 is the number of days from 0001-01-01 to 1970-01-01, + // assuming the Gregorian calendar. + return Time(time_internal::MakeDuration(-24 * 719162 * int64_t{3600}, 0U)); +} + +// InfiniteFuture() +// +// Returns an `absl::Time` that is infinitely far in the future. +constexpr Time InfiniteFuture() { + return Time( + time_internal::MakeDuration(std::numeric_limits<int64_t>::max(), ~0U)); +} + +// InfinitePast() +// +// Returns an `absl::Time` that is infinitely far in the past. +constexpr Time InfinitePast() { + return Time( + time_internal::MakeDuration(std::numeric_limits<int64_t>::min(), ~0U)); +} + +// TimeConversion +// +// An `absl::TimeConversion` represents the conversion of year, month, day, +// hour, minute, and second values (i.e., a civil time), in a particular +// `absl::TimeZone`, to a time instant (an absolute time), as returned by +// `absl::ConvertDateTime()`. (Subseconds must be handled separately.) +// +// It is possible, though, for a caller to try to convert values that +// do not represent an actual or unique instant in time (due to a shift +// in UTC offset in the `absl::TimeZone`, which results in a discontinuity in +// the civil-time components). For example, a daylight-saving-time +// transition skips or repeats civil times---in the United States, March +// 13, 2011 02:15 never occurred, while November 6, 2011 01:15 occurred +// twice---so requests for such times are not well-defined. +// +// To account for these possibilities, `absl::TimeConversion` is richer +// than just a single `absl::Time`. When the civil time is skipped or +// repeated, `absl::ConvertDateTime()` returns times calculated using the +// pre-transition and post-transition UTC offsets, plus the transition +// time itself. +// +// Examples: +// +// absl::TimeZone lax; +// if (!absl::LoadTimeZone("America/Los_Angeles", &lax)) { ... } +// +// // A unique civil time +// absl::TimeConversion jan01 = +// absl::ConvertDateTime(2011, 1, 1, 0, 0, 0, lax); +// // jan01.kind == TimeConversion::UNIQUE +// // jan01.pre is 2011/01/01 00:00:00 -0800 +// // jan01.trans is 2011/01/01 00:00:00 -0800 +// // jan01.post is 2011/01/01 00:00:00 -0800 +// +// // A Spring DST transition, when there is a gap in civil time +// absl::TimeConversion mar13 = +// absl::ConvertDateTime(2011, 3, 13, 2, 15, 0, lax); +// // mar13.kind == TimeConversion::SKIPPED +// // mar13.pre is 2011/03/13 03:15:00 -0700 +// // mar13.trans is 2011/03/13 03:00:00 -0700 +// // mar13.post is 2011/03/13 01:15:00 -0800 +// +// // A Fall DST transition, when civil times are repeated +// absl::TimeConversion nov06 = +// absl::ConvertDateTime(2011, 11, 6, 1, 15, 0, lax); +// // nov06.kind == TimeConversion::REPEATED +// // nov06.pre is 2011/11/06 01:15:00 -0700 +// // nov06.trans is 2011/11/06 01:00:00 -0800 +// // nov06.post is 2011/11/06 01:15:00 -0800 +// +// The input month, day, hour, minute, and second values can also be +// outside of their valid ranges, in which case they will be "normalized" +// during the conversion. +// +// Example: +// +// // "October 32" normalizes to "November 1". +// absl::TimeZone tz = absl::LocalTimeZone(); +// absl::TimeConversion tc = +// absl::ConvertDateTime(2013, 10, 32, 8, 30, 0, tz); +// // tc.kind == TimeConversion::UNIQUE && tc.normalized == true +// // tc.pre.In(tz).month == 11 && tc.pre.In(tz).day == 1 +struct TimeConversion { + Time pre; // time calculated using the pre-transition offset + Time trans; // when the civil-time discontinuity occurred + Time post; // time calculated using the post-transition offset + + enum Kind { + UNIQUE, // the civil time was singular (pre == trans == post) + SKIPPED, // the civil time did not exist + REPEATED, // the civil time was ambiguous + }; + Kind kind; + + bool normalized; // input values were outside their valid ranges +}; + +// ConvertDateTime() +// +// The full generality of a civil time to absl::Time conversion. +TimeConversion ConvertDateTime(int64_t year, int mon, int day, int hour, + int min, int sec, TimeZone tz); + +// FromDateTime() +// +// A convenience wrapper for `absl::ConvertDateTime()` that simply returns the +// "pre" `absl::Time`. That is, the unique result, or the instant that +// is correct using the pre-transition offset (as if the transition +// never happened). This is typically the answer that humans expected when +// faced with non-unique times, such as near daylight-saving time transitions. +// +// Example: +// +// absl::TimeZone seattle; +// if (!absl::LoadTimeZone("America/Los_Angeles", &seattle)) { ... } +// absl::Time t = absl::FromDateTime(2017, 9, 26, 9, 30, 0, seattle); +Time FromDateTime(int64_t year, int mon, int day, int hour, int min, int sec, + TimeZone tz); + +// FromTM() +// +// Converts the `tm_year`, `tm_mon`, `tm_mday`, `tm_hour`, `tm_min`, and +// `tm_sec` fields to an `absl::Time` using the given time zone. See ctime(3) +// for a description of the expected values of the tm fields. IFF the indicated +// time instant is not unique (see `absl::ConvertDateTime()` above), the +// `tm_isdst` field is consulted to select the desired instant (`tm_isdst` > 0 +// means DST, `tm_isdst` == 0 means no DST, `tm_isdst` < 0 means use the default +// like `absl::FromDateTime()`). +Time FromTM(const struct tm& tm, TimeZone tz); + +// ToTM() +// +// Converts the given `absl::Time` to a struct tm using the given time zone. +// See ctime(3) for a description of the values of the tm fields. +struct tm ToTM(Time t, TimeZone tz); + +// FromUnixNanos() +// FromUnixMicros() +// FromUnixMillis() +// FromUnixSeconds() +// FromTimeT() +// FromUDate() +// FromUniversal() +// +// Creates an `absl::Time` from a variety of other representations. +constexpr Time FromUnixNanos(int64_t ns); +constexpr Time FromUnixMicros(int64_t us); +constexpr Time FromUnixMillis(int64_t ms); +constexpr Time FromUnixSeconds(int64_t s); +constexpr Time FromTimeT(time_t t); +Time FromUDate(double udate); +Time FromUniversal(int64_t universal); + +// ToUnixNanos() +// ToUnixMicros() +// ToUnixMillis() +// ToUnixSeconds() +// ToTimeT() +// ToUDate() +// ToUniversal() +// +// Converts an `absl::Time` to a variety of other representations. Note that +// these operations round down toward negative infinity where necessary to +// adjust to the resolution of the result type. Beware of possible time_t +// over/underflow in ToTime{T,val,spec}() on 32-bit platforms. +int64_t ToUnixNanos(Time t); +int64_t ToUnixMicros(Time t); +int64_t ToUnixMillis(Time t); +int64_t ToUnixSeconds(Time t); +time_t ToTimeT(Time t); +double ToUDate(Time t); +int64_t ToUniversal(Time t); + +// DurationFromTimespec() +// DurationFromTimeval() +// ToTimespec() +// ToTimeval() +// TimeFromTimespec() +// TimeFromTimeval() +// ToTimespec() +// ToTimeval() +// +// Some APIs use a timespec or a timeval as a Duration (e.g., nanosleep(2) +// and select(2)), while others use them as a Time (e.g. clock_gettime(2) +// and gettimeofday(2)), so conversion functions are provided for both cases. +// The "to timespec/val" direction is easily handled via overloading, but +// for "from timespec/val" the desired type is part of the function name. +Duration DurationFromTimespec(timespec ts); +Duration DurationFromTimeval(timeval tv); +timespec ToTimespec(Duration d); +timeval ToTimeval(Duration d); +Time TimeFromTimespec(timespec ts); +Time TimeFromTimeval(timeval tv); +timespec ToTimespec(Time t); +timeval ToTimeval(Time t); + +// RFC3339_full +// RFC3339_sec +// +// FormatTime()/ParseTime() format specifiers for RFC3339 date/time strings, +// with trailing zeros trimmed or with fractional seconds omitted altogether. +// +// Note that RFC3339_sec[] matches an ISO 8601 extended format for date +// and time with UTC offset. +extern const char RFC3339_full[]; // %Y-%m-%dT%H:%M:%E*S%Ez +extern const char RFC3339_sec[]; // %Y-%m-%dT%H:%M:%S%Ez + +// RFC1123_full +// RFC1123_no_wday +// +// FormatTime()/ParseTime() format specifiers for RFC1123 date/time strings. +extern const char RFC1123_full[]; // %a, %d %b %E4Y %H:%M:%S %z +extern const char RFC1123_no_wday[]; // %d %b %E4Y %H:%M:%S %z + +// FormatTime() +// +// Formats the given `absl::Time` in the `absl::TimeZone` according to the +// provided format std::string. Uses strftime()-like formatting options, with +// the following extensions: +// +// - %Ez - RFC3339-compatible numeric time zone (+hh:mm or -hh:mm) +// - %E#S - Seconds with # digits of fractional precision +// - %E*S - Seconds with full fractional precision (a literal '*') +// - %E#f - Fractional seconds with # digits of precision +// - %E*f - Fractional seconds with full precision (a literal '*') +// - %E4Y - Four-character years (-999 ... -001, 0000, 0001 ... 9999) +// +// Note that %E0S behaves like %S, and %E0f produces no characters. In +// contrast %E*f always produces at least one digit, which may be '0'. +// +// Note that %Y produces as many characters as it takes to fully render the +// year. A year outside of [-999:9999] when formatted with %E4Y will produce +// more than four characters, just like %Y. +// +// We recommend that format strings include %Ez so that the result uniquely +// identifies a time instant. +// +// Example: +// +// absl::TimeZone lax; +// if (!absl::LoadTimeZone("America/Los_Angeles", &lax)) { ... } +// absl::Time t = absl::FromDateTime(2013, 1, 2, 3, 4, 5, lax); +// +// std::string f = absl::FormatTime("%H:%M:%S", t, lax); // "03:04:05" +// f = absl::FormatTime("%H:%M:%E3S", t, lax); // "03:04:05.000" +// +// Note: If the given `absl::Time` is `absl::InfiniteFuture()`, the returned +// std::string will be exactly "infinite-future". If the given `absl::Time` is +// `absl::InfinitePast()`, the returned std::string will be exactly "infinite-past". +// In both cases the given format std::string and `absl::TimeZone` are ignored. +// +std::string FormatTime(const std::string& format, Time t, TimeZone tz); + +// Convenience functions that format the given time using the RFC3339_full +// format. The first overload uses the provided TimeZone, while the second +// uses LocalTimeZone(). +std::string FormatTime(Time t, TimeZone tz); +std::string FormatTime(Time t); + +// Output stream operator. +inline std::ostream& operator<<(std::ostream& os, Time t) { + return os << FormatTime(t); +} + +// ParseTime() +// +// Parses an input std::string according to the provided format std::string and +// returns the corresponding `absl::Time`. Uses strftime()-like formatting +// options, with the same extensions as FormatTime(), but with the +// exceptions that %E#S is interpreted as %E*S, and %E#f as %E*f. +// +// %Y consumes as many numeric characters as it can, so the matching data +// should always be terminated with a non-numeric. %E4Y always consumes +// exactly four characters, including any sign. +// +// Unspecified fields are taken from the default date and time of ... +// +// "1970-01-01 00:00:00.0 +0000" +// +// For example, parsing a std::string of "15:45" (%H:%M) will return a absl::Time +// that represents "1970-01-01 15:45:00.0 +0000". Note: Since ParseTime() +// returns time instants, it makes the most sense to parse fully-specified +// date/time strings that include a UTC offset (%z/%Ez), such as those +// matching RFC3339_full above. +// +// Note also that `absl::ParseTime()` only heeds the fields year, month, day, +// hour, minute, (fractional) second, and UTC offset. Other fields, like +// weekday (%a or %A), while parsed for syntactic validity, are ignored +// in the conversion. +// +// Date and time fields that are out-of-range will be treated as errors +// rather than normalizing them like `absl::FromDateTime()` does. For example, +// it is an error to parse the date "Oct 32, 2013" because 32 is out of range. +// +// A leap second of ":60" is normalized to ":00" of the following minute +// with fractional seconds discarded. The following table shows how the +// given seconds and subseconds will be parsed: +// +// "59.x" -> 59.x // exact +// "60.x" -> 00.0 // normalized +// "00.x" -> 00.x // exact +// +// Errors are indicated by returning false and assigning an error message +// to the "err" out param if it is non-null. +// +// Note: If the input std::string is exactly "infinite-future", the returned +// `absl::Time` will be `absl::InfiniteFuture()` and `true` will be returned. +// If the input std::string is "infinite-past", the returned `absl::Time` will be +// `absl::InfinitePast()` and `true` will be returned. +// +bool ParseTime(const std::string& format, const std::string& input, + Time* time, std::string* err); + +// Like ParseTime() above, but if the format std::string does not contain a UTC +// offset specification (%z/%Ez) then the input is interpreted in the given +// TimeZone. This means that the input, by itself, does not identify a +// unique instant. Being time-zone dependent, it also admits the possibility +// of ambiguity or non-existence, in which case the "pre" time (as defined +// for ConvertDateTime()) is returned. For these reasons we recommend that +// all date/time strings include a UTC offset so they're context independent. +bool ParseTime(const std::string& format, const std::string& input, TimeZone tz, + Time* time, std::string* err); + +// TODO(b/63899288) copybara strip once dependencies are removed. + +// ParseFlag() +// UnparseFlag() +// +// Support for flag values of type Time. Time flags must be specified in a +// format that matches absl::RFC3339_full. For example: +// +// --start_time=2016-01-02T03:04:05.678+08:00 +// +// Note: A UTC offset (or 'Z' indicating a zero-offset from UTC) is required. +// If your application doesn't have a UTC offset to specify, perhaps you're +// really specifying a Civil Time +// Additionally, if you'd like to specify a time as a count of +// seconds/milliseconds/etc from the Unix epoch, use a absl::Duration flag and +// add that duration to absl::UnixEpoch() to get a absl::Time. +bool ParseFlag(const std::string& text, Time* t, std::string* error); +std::string UnparseFlag(Time t); + +// TimeZone +// +// The `absl::TimeZone` is an opaque, small, value-type class representing a +// geo-political region within which particular rules are used for converting +// between absolute and civil times (see https://git.io/v59Ly). `absl::TimeZone` +// values are named using the TZ identifiers from the IANA Time Zone Database, +// such as "America/Los_Angeles" or "Australia/Sydney". `absl::TimeZone` values +// are created from factory functions such as `absl::LoadTimeZone()`. Note: +// strings like "PST" and "EDT" are not valid TZ identifiers. Prefer to pass by +// value rather than const reference. +// +// For more on the fundamental concepts of time zones, absolute times, and civil +// times, see https://github.com/google/cctz#fundamental-concepts +// +// Examples: +// +// absl::TimeZone utc = absl::UTCTimeZone(); +// absl::TimeZone pst = absl::FixedTimeZone(-8 * 60 * 60); +// absl::TimeZone loc = absl::LocalTimeZone(); +// absl::TimeZone lax; +// if (!absl::LoadTimeZone("America/Los_Angeles", &lax)) { ... } +// +// See also: +// - https://github.com/google/cctz +// - http://www.iana.org/time-zones +// - http://en.wikipedia.org/wiki/Zoneinfo +// TimeZone backing data with your binary. +class TimeZone { + public: + explicit TimeZone(cctz::time_zone tz) : cz_(tz) {} + TimeZone() = default; // UTC, but prefer UTCTimeZone() to be explicit. + TimeZone(const TimeZone&) = default; + TimeZone& operator=(const TimeZone&) = default; + + explicit operator cctz::time_zone() const { return cz_; } + + std::string name() const { return cz_.name(); } + + private: + friend bool operator==(TimeZone a, TimeZone b) { return a.cz_ == b.cz_; } + friend bool operator!=(TimeZone a, TimeZone b) { return a.cz_ != b.cz_; } + friend std::ostream& operator<<(std::ostream& os, TimeZone tz) { + return os << tz.name(); + } + + cctz::time_zone cz_; +}; + +// LoadTimeZone() +// +// Loads the named zone. May perform I/O on the initial load of the named +// zone. If the name is invalid, or some other kind of error occurs, returns +// `false` and `*tz` is set to the UTC time zone. +inline bool LoadTimeZone(const std::string& name, TimeZone* tz) { + if (name == "localtime") { + *tz = TimeZone(cctz::local_time_zone()); + return true; + } + cctz::time_zone cz; + const bool b = cctz::load_time_zone(name, &cz); + *tz = TimeZone(cz); + return b; +} + +// FixedTimeZone() +// +// Returns a TimeZone that is a fixed offset (seconds east) from UTC. +// Note: If the absolute value of the offset is greater than 24 hours +// you'll get UTC (i.e., no offset) instead. +inline TimeZone FixedTimeZone(int seconds) { + return TimeZone(cctz::fixed_time_zone(std::chrono::seconds(seconds))); +} + +// UTCTimeZone() +// +// Convenience method returning the UTC time zone. +inline TimeZone UTCTimeZone() { return TimeZone(cctz::utc_time_zone()); } + +// LocalTimeZone() +// +// Convenience method returning the local time zone, or UTC if there is +// no configured local zone. Warning: Be wary of using LocalTimeZone(), +// and particularly so in a server process, as the zone configured for the +// local machine should be irrelevant. Prefer an explicit zone name. +inline TimeZone LocalTimeZone() { return TimeZone(cctz::local_time_zone()); } + +// ============================================================================ +// Implementation Details Follow +// ============================================================================ + +namespace time_internal { + +// Creates a Duration with a given representation. +// REQUIRES: hi,lo is a valid representation of a Duration as specified +// in time/duration.cc. +constexpr Duration MakeDuration(int64_t hi, uint32_t lo = 0) { + return Duration(hi, lo); +} + +constexpr Duration MakeDuration(int64_t hi, int64_t lo) { + return time_internal::MakeDuration(hi, static_cast<uint32_t>(lo)); +} + +// Creates a normalized Duration from an almost-normalized (sec,ticks) +// pair. 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 in the resulting Duration. +constexpr Duration MakeNormalizedDuration(int64_t sec, int64_t ticks) { + return (ticks < 0) + ? time_internal::MakeDuration(sec - 1, ticks + kTicksPerSecond) + : time_internal::MakeDuration(sec, ticks); +} +// Provide access to the Duration representation. +constexpr int64_t GetRepHi(Duration d) { return d.rep_hi_; } +constexpr uint32_t GetRepLo(Duration d) { return d.rep_lo_; } +constexpr bool IsInfiniteDuration(Duration d) { return GetRepLo(d) == ~0U; } + +// Returns an infinite Duration with the opposite sign. +// REQUIRES: IsInfiniteDuration(d) +constexpr Duration OppositeInfinity(Duration d) { + return GetRepHi(d) < 0 + ? MakeDuration(std::numeric_limits<int64_t>::max(), ~0U) + : MakeDuration(std::numeric_limits<int64_t>::min(), ~0U); +} + +// Returns (-n)-1 (equivalently -(n+1)) without overflowing on any input value. +constexpr int64_t NegateAndSubtractOne(int64_t n) { + return (n < 0) ? -(n + 1) : (-n) - 1; +} + +// Map between a Time and a Duration since the Unix epoch. Note that these +// functions depend on the above mentioned choice of the Unix epoch for the +// Time representation (and both need to be Time friends). Without this +// knowledge, we would need to add-in/subtract-out UnixEpoch() respectively. +constexpr Time FromUnixDuration(Duration d) { return Time(d); } +constexpr Duration ToUnixDuration(Time t) { return t.rep_; } +} // namespace time_internal + +constexpr bool operator<(Duration lhs, Duration rhs) { + return time_internal::GetRepHi(lhs) != time_internal::GetRepHi(rhs) + ? time_internal::GetRepHi(lhs) < time_internal::GetRepHi(rhs) + : time_internal::GetRepHi(lhs) == std::numeric_limits<int64_t>::min() + ? time_internal::GetRepLo(lhs) + 1 < + time_internal::GetRepLo(rhs) + 1 + : time_internal::GetRepLo(lhs) < + time_internal::GetRepLo(rhs); +} + +constexpr bool operator==(Duration lhs, Duration rhs) { + return time_internal::GetRepHi(lhs) == time_internal::GetRepHi(rhs) && + time_internal::GetRepLo(lhs) == time_internal::GetRepLo(rhs); +} + +constexpr Duration operator-(Duration d) { + // This is a little interesting because of the special cases. + // + // Infinities stay infinite, and just change direction. + // + // The maximum negative finite duration can't be negated (at least, not + // on a two's complement machine), so we return infinity for that case. + // Next we dispatch the case where rep_lo_ is zero, observing that it's + // safe to negate rep_hi_ in this case because it's not int64_t-min (or + // else we'd have handled it above, returning InfiniteDuration()). + // + // Finally we're in the case where rep_lo_ is non-zero, and we can borrow + // a second's worth of ticks and avoid overflow (as negating int64_t-min + 1 + // is safe). + return time_internal::IsInfiniteDuration(d) + ? time_internal::OppositeInfinity(d) + : (time_internal::GetRepHi(d) == + std::numeric_limits<int64_t>::min() && + time_internal::GetRepLo(d) == 0) + ? InfiniteDuration() + : (time_internal::GetRepLo(d) == 0) + ? time_internal::MakeDuration( + -time_internal::GetRepHi(d)) + : time_internal::MakeDuration( + time_internal::NegateAndSubtractOne( + time_internal::GetRepHi(d)), + time_internal::kTicksPerSecond - + time_internal::GetRepLo(d)); +} + +constexpr Duration Nanoseconds(int64_t n) { + return time_internal::MakeNormalizedDuration( + n / (1000 * 1000 * 1000), + n % (1000 * 1000 * 1000) * time_internal::kTicksPerNanosecond); +} + +constexpr Duration Microseconds(int64_t n) { + return time_internal::MakeNormalizedDuration( + n / (1000 * 1000), + n % (1000 * 1000) * (1000 * time_internal::kTicksPerNanosecond)); +} + +constexpr Duration Milliseconds(int64_t n) { + return time_internal::MakeNormalizedDuration( + n / 1000, n % 1000 * (1000 * 1000 * time_internal::kTicksPerNanosecond)); +} + +constexpr Duration Seconds(int64_t n) { return time_internal::MakeDuration(n); } + +constexpr Duration Minutes(int64_t n) { + return (n <= std::numeric_limits<int64_t>::max() / 60 && + n >= std::numeric_limits<int64_t>::min() / 60) + ? time_internal::MakeDuration(n * 60) + : n > 0 ? InfiniteDuration() : -InfiniteDuration(); +} + +constexpr Duration Hours(int64_t n) { + return (n <= std::numeric_limits<int64_t>::max() / 3600 && + n >= std::numeric_limits<int64_t>::min() / 3600) + ? time_internal::MakeDuration(n * 3600) + : n > 0 ? InfiniteDuration() : -InfiniteDuration(); +} + +constexpr Duration InfiniteDuration() { + return time_internal::MakeDuration(std::numeric_limits<int64_t>::max(), ~0U); +} + +constexpr Time FromUnixNanos(int64_t ns) { + return time_internal::FromUnixDuration(Nanoseconds(ns)); +} + +constexpr Time FromUnixMicros(int64_t us) { + return time_internal::FromUnixDuration(Microseconds(us)); +} + +constexpr Time FromUnixMillis(int64_t ms) { + return time_internal::FromUnixDuration(Milliseconds(ms)); +} + +constexpr Time FromUnixSeconds(int64_t s) { + return time_internal::FromUnixDuration(Seconds(s)); +} + +constexpr Time FromTimeT(time_t t) { + return time_internal::FromUnixDuration(Seconds(t)); +} + +} // namespace absl + +#endif // ABSL_TIME_TIME_H_ |