Retrieve the current time from remote servers.

It works by requesting timestamps from twelve very popular hosts over https. As soon as it gets at least three responses, it takes the two that have the smallest difference in time. And from those two it picks the one that is the oldest. Finally it ensures that the time is monotonic.

go get -u github.com/tidwall/rtime

Get the remote time with rtime.Now().

tm := rtime.Now()
if tm.IsZero() {
    panic("internet offline")
}
println(tm.String())
// output: 2020-03-29 10:27:00 -0700 MST
}

The rtime.Now() will be a little slow, usually 200 ms or more, because it must make a round trip to three or more remote servers to determine the correct time.

You can make it fast like the built-in time.Now() by calling rtime.Sync() once at the start of your application.

if err := rtime.Sync(); err != nil {
    panic(err)
}
// All following rtime.Now() calls will now be quick and without the need for
// checking its result.
tm := rtime.Now()
println(tm.String())

It's a good idea to call rtime.Sync() at the top of the main() or init() functions.

Josh Baker @tidwall

Source code is available under the MIT License.