Why coroutineScope { ...} function is not implicit inside suspend functions?

fvasco · January 15, 2020, 11:17am

Maybe this is the answer that are you looking for

github.com/Kotlin/kotlinx.coroutines

Provide abstraction for cold streams

opened 12:06PM - 21 Feb 18 UTC

closed 12:57PM - 13 Apr 19 UTC

elizarov

enhancement

All the currently provided channel abstractions in `kotlinx.coroutines` are _hot…_. The data is being produced regardless of the presence of subscriber. This is good for data sources and applications that are inherently hot, like incoming network and UI-events. However, hot streams are not an ideal solution for cases where data stream is produced on demand. Consider, for example, the following simple code that produces `ReceiveChannel<Int>`: ``` produce<Int> { while (true) { val x = computeNextValue() send(x) } } ``` One obvious downside is the `computeNextValue()` is invoked before `send`, so even when receiver is not ready, the next value gets computed. Of course, it gets suspended in `send` if there is no receiver, but it is not as lazy as you get with cold reactive Publisher/Observable/Flowable/Flux/Flow. We need the abstraction for cold streams in `kotlinx.coroutines` that is going to be just as lazy, computing data in "push" mode versus "pull" mode of hot channels that we have now. There are the following related discussions: * https://github.com/reactor/reactor-core/issues/979#issuecomment-351770494 describes preliminary performance test that indicates that "push" mode is much faster for same-thread cases. * https://github.com/Kotlin/kotlinx.coroutines/issues/113 (SPSC channels) seems to get superseded by the support of cold streams.

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Why coroutineScope { ...} function is not implicit inside suspend functions?

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