Time 
#include "co/time.h"

flag::parse is not required.

sleep is in the time namespace; the rest are in the co namespace.

#Current Time co::now

struct Now {
    static int64 ns();   // nanoseconds, may overflow in 2262
    static int64 us();   // microseconds
    static int64 ms();   // milliseconds
    static co::string str(const char* fmt="%Y-%m-%d %H:%M:%S");
};
  • ns() / us() / ms() return Unix epoch timestamps (UTC).
  • str() is based on strftime and returns a local time string.

#Monotonic Clock co::mono_time

struct MonoTime {
    static int64 ns();
    static int64 us();
    static int64 ms();
};
  • Based on std::chrono::steady_clock.
  • Monotonically increasing, suitable for measuring time differences.

#Timer co::timer

struct timer {
    timer();
    void restart();
    int64 ns() const;
    int64 us() const;
    int64 ms() const;
};
  • Records the start point on construction.
  • restart() resets the start point.
  • ns() / us() / ms() return the elapsed time from the start point to now.
  • Based on mono_time.

#Sleep time::sleep

void time::sleep(uint32 ms);
  • Unit is milliseconds.
  • Thread-level sleep, blocks the current thread.
  • Cannot be used in a coroutine; use co::sleep in coroutines.

#Example

#include "co/time.h"
#include "co/print.h"

int main() {
    co::println("now.ns() = ", co::now.ns());
    co::println("now.us() = ", co::now.us());
    co::println("now.ms() = ", co::now.ms());
    co::println("now.str() = ", co::now.str());
    co::println("now.str(%Y%m%d) = ", co::now.str("%Y%m%d"));

    co::println("mono.ns() = ", co::mono_time.ns());
    co::println("mono.us() = ", co::mono_time.us());
    co::println("mono.ms() = ", co::mono_time.ms());

    co::timer t;
    time::sleep(100);
    co::println("elapsed ns = ", t.ns());
    co::println("elapsed us = ", t.us());
    co::println("elapsed ms = ", t.ms());

    t.restart();
    time::sleep(50);
    co::println("after restart, ms = ", t.ms());
    return 0;
}