is there any way to achieve something similiar with the `throttle` operator using coroutines?

# coroutines

[igorvd]

is there any way to achieve something similiar with the throttle operator using coroutines?

[Vsevolod Tolstopyatov [JB]]

It’s easy to implement with incoming delay channel (https://github.com/Kotlin/kotlinx.coroutines/issues/327)

fun <T> Publisher<T>.throttle(intervalMs: Long) = publish<T> {
    val delayChannel = DelayChannel(intervalMs)
    openSubscription().use { channel ->
        var shouldSend = true
        whileSelect {

            delayChannel.onReceive {
                shouldSend = true
                true
            }

            channel.onReceiveOrNull {
                when {
                    it == null -> false
                    shouldSend -> {
                        shouldSend = false
                        send(it)
                        true
                    }
                    else -> true
                }
            }
        }
    }
}

[igorvd]

OK I'll try it. Thank you!

[bj0]

You don't really need a delayChannel, you can just use an onTimeout in the select claus

[Vsevolod Tolstopyatov [JB]]

@bj0 It’s not true, onTimeout has different semantics, it’s rescheduled (delayed) on every onReceiveOrNull selection, while DelayChannel#onReceive is not

[bj0]

isn't that how throttle works in rx?

[Vsevolod Tolstopyatov [JB]]

No.
In my example for something like
rangeWithDelay(1, 10, 100ms).throttle(200ms).consumeEach{println(it)}
1 3 5 7 9 will be printed.
If I’ll replace DelayChannel with onTimeout, only 1 will be printed

[bj0]

http://www.introtorx.com/content/v1.0.10621.0/13_TimeShiftedSequences.html#Throttle

[bj0]

throttle resets its window when it receives a new value

[bj0]

or it did last time i used rx

[Vsevolod Tolstopyatov [JB]]

we were talking about different things 🙂
http://reactivex.io/documentation/operators/sample.html I’ve implemented throttleFirst.
In case of throttle from rx1, onTimeout should be used