Which is the best way to measure elapsed time in e...

# getting-started

[Nicola]

Which is the best way to measure elapsed time in executing a function?
Now I would go with something like this

val start = System.nanoTime()
execute_my_function()
val duration = System.nanoTime() - start

Would it be ok or are there better ways?

[mkrussel]

Kotlin has some built in functions measureTime , measureTimeInNanos, measureTimedValue.

You pass a block into the measure functions and they will return how long it took.

[Vampire]

val duration = measureTime {
    execute_my_function()
}

[Nicola]

Thanks, but does it work even when the function returns a value to the caller?
eg

val startTime = System.nanoTime()
val response = execute_my_function()
val duration = System.nanoTime() - startTime

[Nicola]

(forgot this detail)

[Nicola]

i'll try

[Nicola]

Ah but that api needs opt-in experimental feature, doesn'it ?

[mkrussel]

The one that returns a Duration needs an opt in. The measureTimeInNanos don't. To get a value, use the one that has value in the name.

[Vampire]

It does, if you don't like that, use measureTimeMillis

[Vampire]

Or to also support return value measureTimedValue

[mkrussel]

Actually I can only find a Value version for the experimental time.

[Vampire]

yes

[Nicola]

measureTimeMillis

ok thanks a lot!

[Vampire]

For non-experimental, you can just set the result property in the lambda that you defined before like shown in the docs

[Vampire]

val result: Int
val timeInMillis = measureTimeMillis {
    result = 1
}

[nkiesel]

I personally would opt-in to measureTimedValue : unlikely to change, and nicer to use that breaking up definition and assignment. And if you want to control the potential impact, then create your own wrapper and use that in your code.