I m trying to coerce Realm to work with coroutines but my `R

Question

I m trying to coerce Realm to work with coroutines but my `ReceiveChannel` is coming back already closed from this signature ``` ExperimentalCoroutinesApi override fun CoroutineScope messageUpdateProducer ReceiveChannel lt List lt Message gt gt = produce realm where RealmMessage class java findAll addChangeListener results gt offer results takeIf it isNotEmpty map it messageActual listOf ``` It looks like from the documentation that if the producer encounters an error it will close automatically but I m not sure what s generating an error in there I m handling all the null cases and my crashes are only generating a stack trace internal to the channel mechanism ``` kotlinx coroutines channels ClosedReceiveChannelException Channel was closed at kotlinx coroutines channels Closed getReceiveException AbstractChannel kt 1094 at kotlinx coroutines channels AbstractChannel$ReceiveSelect resumeReceiveClosed AbstractChannel kt 993 at kotlinx coroutines channels AbstractSendChannel helpClose AbstractChannel kt 332 at kotlinx coroutines channels AbstractSendChannel close AbstractChannel kt 271 at kotlinx coroutines channels SendChannel$DefaultImpls close$default Channel kt 95 at kotlinx coroutines channels ProducerCoroutine onCompleted Produce kt 98 at kotlinx coroutines channels ProducerCoroutine onCompleted Produce kt 91 at kotlinx coroutines AbstractCoroutine onCompletionInternal AbstractCoroutine kt 102 at kotlinx coroutines JobSupport tryFinalizeSimpleState JobSupport kt 274 at kotlinx coroutines JobSupport tryMakeCompleting JobSupport kt 784 at kotlinx coroutines JobSupport makeCompletingOnce$kotlinx coroutines core JobSupport kt 764 at kotlinx coroutines AbstractCoroutine resumeWith AbstractCoroutine kt 111 at kotlin coroutines jvm internal BaseContinuationImpl resumeWith ContinuationImpl kt 46 at kotlinx coroutines DispatchedTask run Dispatched kt 238 at android os Handler handleCallback Handler java 739 at android os Handler dispatchMessage Handler java 95 at android os Looper loop Looper java 135 at android app ActivityThread main ActivityThread java 5223 at java lang reflect Method invoke Native Method at java lang reflect Method invoke Method java 372 at com android internal os ZygoteInit$MethodAndArgsCaller run ZygoteInit java 899 at com android internal os ZygoteInit main ZygoteInit java 694 ```

zak.taccardi · Answer

once the `produce` completes the receive channel may be closed I don t remember

rook · Answer

oh interesting I thought channels were hot thinking face

Dominaezzz · Answer

You don t need `produce` here

Dominaezzz · Answer

Just create a channel and then return it

Dominaezzz · Answer

< zak taccardi> is right

rook · Answer

Thanks I guess I still don t fully understand `produce`

Dico · Answer

You need to unregister the change listener when the channel is closed though

Adam Powell · Answer

in a `ProducerScope` you can do that with `awaitClose ` at the end of the produce block and unregister in that block

Adam Powell · Answer

or make the whole thing simpler and use the same code from the `produce` block with the `awaitClose` added but with `channelFlow` instead of `produce` you won t need the `CoroutineScope` and you get a cold stream

rook · Answer

Cold stream meaning that it doesn t start emitting values until it s been subscribed to