Kotlin coroutine update.

[rozza]

The Flow interface is not stable for inheritance in 3rd party libraries. Updated code to use the AbstractFlow as recommended instead via the sealed MongoAbstractFlow class.

JAVA-4950

[stIncMale]

I looked at the changes, and I don't have objections, which is expected, given that I don't know Kotlin. However, I also can't reasonably approve the PR, so I will stay a bystander.

[rozza]

Hi @zigzago - just wanted to double check you are happy with this PR

[vsct-jburet]

Hi @zigzago - just wanted to double check you are happy with this PR

If you look at the implementation of MongoAbstractFlow, it adds some behaviour

public final override suspend fun collect(collector: FlowCollector<T>) {
        val safeCollector = SafeCollector(collector, coroutineContext)
        try {
            collectSafely(safeCollector)
        } finally {
            safeCollector.releaseIntercepted()
        }
    }

Also in the doc of AbstractFlow (https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/-abstract-flow/):

"Base class for stateful implementations of Flow". I'm not sure that mongo flows are stateful.

I don't say your implementation will not work, but it would be cleaner for my point of view to use the kotlin delegate pattern:

class AggregateFlow<T : Any>(private val wrapped: AggregatePublisher<T>) : Flow<T> by wrapped.asFlow()

Then you rely completely on Publisher.asFlow() kotlin implementation (which is safe).

HTH

Julien

[rozza]

Hi @vsct-jburet,

Good points, they are stateful in that they contain the cursor state, but that is all managed by the Publisher and not the Flow.

Will update to MongoFlow and delegate instead. Will revert and delegate instead.

Ross