Hey all. I have a problem I’m stumped by. I have a block of code that I invoke once, but it runs twice. If anyone has some guidance/intuition/experience with a similar problem, I’d love the assist. Code is here:

suspend fun <E: Event> dispatch(command: Command): Effect<WorkflowError, E> {
    log.debug("BEFORE EFFECT")
    return effect {
      log.debug("START EFFECT")
      ensureNotNull(commandHandlers[command::class]) {
        MissingHandler("No handler for command $command")
      }.let {
        it.invoke(command) as E
      }
    }
  }

The signature of the

invoke

method, if this helps:

context(EffectScope<WorkflowError>)
  final override suspend fun invoke(request: R): E {

Log output:

2023-03-22T21:07:07.106-04:00 DEBUG 38879 --- [-5 @coroutine#7] i.l.common.workflow.WorkflowDispatcher   : BEFORE EFFECT
2023-03-22T21:07:07.107-04:00 DEBUG 38879 --- [-5 @coroutine#7] i.l.common.workflow.WorkflowDispatcher   : START EFFECT
...
2023-03-22T21:07:07.175-04:00 DEBUG 38879 --- [-3 @coroutine#7] i.l.common.workflow.WorkflowDispatcher   : START EFFECT

Where is the code that consumes the effect though? I think you might be invoking the effect itself twice

Oh interesting. I’ll investigate that. Thx for the insight

Oh yeah, that makes sense. Effect "basically" returns an Either, and so what happened is that you were recomputing that either twice, thus producing side effects.

Thx for the assist!