48 lines
2.5 KiB
C++
48 lines
2.5 KiB
C++
#pragma once
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namespace ro {
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// need to define my own time types:
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typedef time_t time_t; // is always time in seconds past the epoch modulo 2 ^ 64
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// equivalent to regular old time_t
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// except in environments where time_t is seconds past the epoch
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// modulo 2 ^ 32
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ro::time_t time();
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// equivalent to regular old time(nullptr);
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// except in environments where time_t is seconds past the epoch modulo 2 ^ 32
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typedef std::chrono::duration<int64_t, std::ratio<1, 1> > sec;
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typedef std::chrono::time_point<std::chrono::system_clock, ro::sec > sec_t;
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ro::sec_t system_time_now();
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// Also equivalent to plain old time_t, except with modern C++14 type distinction
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// between time points and time durations
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std::string iso_utc_time(ro::time_t t);
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std::string iso_utc_time(ro::sec_t t);
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// which is a string expressing the utc time
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std::string iso_local_time(ro::time_t t);
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std::string iso_local_time(ro::sec_t t);
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// which is a string expressing the local time
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typedef std::chrono::duration<uint32_t, std::ratio<1, 1000> > msec;
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// duration past startup time modulo 2^32 Rolls over every forty eight days, making
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// durations longer than twenty four days of unclear sign
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msec msec_since_epoch(void);
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// Obliterates chrono's elegant but pain in the ass distinction between time points and
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// durations. Which type distinction in practice gets in the way off all sorts of things
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// that just need to be done.
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// In truth, it is a distinction that only matters, and is indeed only meaningful, with
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// respect to shared global consensus time, universal coordinated time. It is not
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// meaningful for steady time or high precision time, which means that all sorts of stuff
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// gets assigned to the wrong type, a duration when you need it to be a time point, or a
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// time point when you need it to be a duration.
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//
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// A time point is just a duration relative to some globally agreed consensus time point,
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// and if you don't have such a consensus, forget it. And when you are measuring
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// millisecond times, you do not have such a consensus.
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//
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// millisecond clocks are not expected to be synchronized between systems, nor to
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// measure milliseconds exactly nor to be exactly the same time unit between systems,
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// but they are expected to advance similarly on both systems for the life of any
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// connection, making the distinction between time points and durations problematic.
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// We expect to compare the change in time on one system, with the change in time
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// on another system, in which case the time point class gets in the way.
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}
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