Supposing I am building a flow operator that uses channel flow, and I know the upstream flow is also...

# coroutines

[Patrick Steiger]

Supposing I am building a flow operator that uses channel flow, and I know the upstream flow is also a channel flow, can I make them fuse?

AFAIK this won’t fuse:

channelFlow {
  channelFlow {
    send(1)
  }.collect { send(it) }
}

[Patrick Steiger]

… to be clear, I don’t think not fusing in this case is a problem since it’s just a perf optimization as far as I understand. Just curious if there’s a publicly exposed way (since FusibleFlow, ChannelFlowOperator, etc are internal)

[Daniel Pitts]

It doesn't look like there is a way to do that. I don't even think it's an optimization really. The thing that "fusing" does is combine the configuration of buffer/context of the flow.

[Daniel Pitts]

Though it seems like this would be better structured as

channelFlow {
   send(1)
}.map { it }

[Patrick Steiger]

Example is contrived, actual code needs to populate the downstream channel from multiple coroutines, where 1 of them is collecting from upstream channel flow and sending to downstream channel flow

[Patrick Steiger]

Thanks for answering though, I think it’s indeed not possible

[Patrick Steiger]

Also you’re right fusing is not (just?) for optimization purposes, since fusing has its own logic for somehow combines the configs (either overriding, or summing, etc