54aa552af7
Moved files: - duration.hh - duration.cc - concrete_types.hh Fixes: #22110 This is a cleanup, no need to backport Closes scylladb/scylladb#25088
130 lines
4.5 KiB
C++
130 lines
4.5 KiB
C++
/*
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* Copyright (C) 2017-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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*/
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#pragma once
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#include <seastar/core/sstring.hh>
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#include <cstdint>
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#include <string_view>
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#include <ostream>
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#include <stdexcept>
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// Wrapper for a value with a type-tag for differentiating instances.
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template <class Value, class Tag>
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class cql_duration_counter final {
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public:
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using value_type = Value;
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explicit constexpr cql_duration_counter(value_type count) noexcept : _count(count) {}
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constexpr operator value_type() const noexcept { return _count; }
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private:
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value_type _count;
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};
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using months_counter = cql_duration_counter<int32_t, struct month_tag>;
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using days_counter = cql_duration_counter<int32_t, struct day_tag>;
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using nanoseconds_counter = cql_duration_counter<int64_t, struct nanosecond_tag>;
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class cql_duration_error : public std::invalid_argument {
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public:
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explicit cql_duration_error(std::string_view what) : std::invalid_argument(what.data()) {}
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virtual ~cql_duration_error() = default;
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};
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//
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// A duration of time.
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//
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// Three counters represent the time: the number of months, of days, and of nanoseconds. This is necessary because
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// the number hours in a day can vary during daylight savings and because the number of days in a month vary.
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//
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// As a consequence of this representation, there can exist no total ordering relation on durations. To see why,
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// consider a duration `1mo5s` (1 month and 5 seconds). In a month with 30 days, this represents a smaller duration of
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// time than in a month with 31 days.
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//
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// The primary use of this type is to manipulate absolute time-stamps with relative offsets. For example,
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// `"Jan. 31 2005 at 23:15" + 3mo5d`.
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//
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class cql_duration final {
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public:
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using common_counter_type = int64_t;
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static_assert(
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(sizeof(common_counter_type) >= sizeof(months_counter::value_type)) &&
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(sizeof(common_counter_type) >= sizeof(days_counter::value_type)) &&
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(sizeof(common_counter_type) >= sizeof(nanoseconds_counter::value_type)),
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"The common counter type is smaller than one of the component counter types.");
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// A zero-valued duration.
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constexpr cql_duration() noexcept = default;
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// Construct a duration with explicit values for its three counters.
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constexpr cql_duration(months_counter m, days_counter d, nanoseconds_counter n) noexcept :
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months(m),
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days(d),
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nanoseconds(n) {}
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//
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// Parse a duration string.
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//
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// Three formats for durations are supported:
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//
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// 1. "Standard" format. This consists of one or more pairs of a count and a unit specifier. Examples are "23d1mo"
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// and "5h23m10s". Components of the total duration must be written in decreasing order. That is, "5h2y" is
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// an invalid duration string.
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//
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// The allowed units are:
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// - "y": years
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// - "mo": months
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// - "w": weeks
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// - "d": days
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// - "h": hours
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// - "m": minutes
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// - "s": seconds
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// - "ms": milliseconds
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// - "us" or "µs": microseconds
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// - "ns": nanoseconds
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//
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// Units are case-insensitive.
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//
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// 2. ISO-8601 format. "P[n]Y[n]M[n]DT[n]H[n]M[n]S" or "P[n]W". All specifiers are optional. Examples are
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// "P23Y1M" or "P10W".
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//
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// 3. ISO-8601 alternate format. "P[YYYY]-[MM]-[DD]T[hh]:[mm]:[ss]". All specifiers are mandatory. An example is
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// "P2000-10-14T07:22:30".
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//
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// For all formats, a negative duration is indicated by beginning the string with the '-' symbol. For example,
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// "-2y10ns".
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//
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// Throws `cql_duration_error` in the event of a parsing error.
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//
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explicit cql_duration(std::string_view s);
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months_counter::value_type months{0};
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days_counter::value_type days{0};
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nanoseconds_counter::value_type nanoseconds{0};
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//
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// Note that equality comparison is based on exact counter matches. It is not valid to expect equivalency across
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// counters like months and days. See the documentation for `duration` for more.
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//
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friend bool operator==(const cql_duration&, const cql_duration&) noexcept = default;
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};
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//
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// Pretty-print a duration using the standard format.
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//
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// Durations are simplified during printing so that `duration(24, 0, 0)` is printed as "2y".
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//
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std::ostream& operator<<(std::ostream& os, const cql_duration& d);
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// See above.
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seastar::sstring to_string(const cql_duration&);
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