How can I refactor this to instead use

kotlin.time.Duration

? I thought this would be simple (it probably still is) but my first attempt didnt result in the behavior I was expecting, and Im not 100% clear on why that is (code for that in 🧵).

fun round(
    duration: Long,
    period: Long = 1000,
): Long {
    val half = period / 2
    return (duration + half) / period * period
}

in your original function with duration as Long,

(duration + half) / period

uses Long division meaning that entire decimal section is cut out, so that for example

(9800 + 500) / 1000

gives 10, whereas

Duration / Duration

uses double division meaning above example would give 10.3. If you want version with

Duration

to give same results as the one with

Long

you may for example use

floor

to ignore decimal part of division:

floor((duration + half) / period) * period

It uses Long (not double) division, but represents the durations in nanoseconds. So, one way to do it is this:

val periodNanos = period.inWholeNanoseconds
    return ((duration + period / 2).inWholeNanoseconds / periodNanos * periodNanos).nanoseconds

@Klitos Kyriacou I'm pretty sure it uses double division unless I'm missing something https://github.com/JetBrains/kotlin/blob/30788566012c571aa1d3590912468d1ebe59983d/libraries/stdlib/src/kotlin/time/Duration.kt#L626

@Szymon Jeziorski you're right. I was looking at

Duration.div(Int)

instead. So it uses Long division for

val half = period / 2

but indeed it uses Double division for dividing by

period

.

Thank you both, that makes perfect sense! 🙏🏽