Hi, is there a version of `SharedFlow` that caches values (like `replayCache`) but DOESN'T play them...

# coroutines

[Ivan Đorđević]

Hi, is there a version of SharedFlow that caches values (like replayCache) but DOESN'T play them back automatically to new subscribers?

[wbertan]

🤔 We use this:

fun <T> MutableSingleSharedFlow() = MutableSharedFlow<T>(
    replay = 1,
    extraBufferCapacity = 1,
    onBufferOverflow = BufferOverflow.DROP_OLDEST
)

Not sure it “DOESN’T play them back automatically” 🤔

[Ivan Đorđević]

Thanks! Although it seems like it would, because replay = 1 so it seems it would replay one value

[bezrukov]

use replay = 0, and extraBufferCapacity=desired buffer size to achieve this

[Ivan Đorđević]

@bezrukov I tried that, but then I can't access the cache since replayCache.size() == 0 still even after emitting something

[bezrukov]

ah I see, you still need to have a direct access to the buffer. So I don't think there is a good built-in way to achieve this.
You probably can play with flow.drop(flow.replayCache.size()) but I don't think it's robust because of different locks (I mean let's say replayCache contains [A,B,C] when you called it, but when you subscribed to it, A is dropped, and replay cache is [B, C, D], so you won't receive D).

[Dominaezzz]

You could subscribe to the SharedFlow early and maintain a list of n items emitted. Maybe even share the shared flow subscription, then you can use the new replay cache. (Although I don't think I'd call this a cache).