Im atempting to stream the PersistenceQuery result with akka-http as SSE but it seems like when the http connection is closed from the client the PersistenceQuery stream is still hitting the event backend periodically.
// Http part
complete {
source(id)
.map(e => e.event) // other transformations
.map(e => ServerSentEvent(m.toString))
.keepAlive(4 seconds, () => ServerSentEvent.heartbeat)
}
// source
def source(id: UUID)(implicit system: ActorSystem, materializer: ActorMaterializer)= {
import system.dispatcher
val journalQuery = PersistenceQuery(system).readJournalFor[CassandraReadJournal](CassandraReadJournal.Identifier)
val futureSrcGraph: RunnableGraph[Future[Source[EventEnvelope, NotUsed]]] =
journalQuery.currentEventsByPersistenceId(id.toString, 0, Long.MaxValue)
.map(_.sequenceNr)
.toMat(Sink.last)(Keep.right)
.mapMaterializedValue(fs => fs.recoverWith {
case _ => Future { 0L } // assume we start at 1
}.map(s => journalQuery.eventsByPersistenceId(id.toString, s + 1, Long.MaxValue)))
Source.fromFutureSource(futureSrcGraph.run())
So this basically works the only problem is that the stream is never finished or so it seems. I have tried it with both CassandraReadJournal and LevelDb
Example of the log output:
[DEBUG] [06/18/2018 10:52:16.774] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query from seqNr [6] in partition [0]
[DEBUG] [06/18/2018 10:52:16.790] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query took [15] ms (empty)
[DEBUG] [06/18/2018 10:52:16.790] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query from seqNr [6] in partition [1]
[DEBUG] [06/18/2018 10:52:16.796] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query took [5] ms (empty)
[DEBUG] [06/18/2018 10:52:19.768] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query from seqNr [6] in partition [0]
[DEBUG] [06/18/2018 10:52:19.784] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query took [15] ms (empty)
[DEBUG] [06/18/2018 10:52:19.784] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query from seqNr [6] in partition [1]
[DEBUG] [06/18/2018 10:52:19.790] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query took [6] ms (empty)
[DEBUG] [06/18/2018 10:52:22.765] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query from seqNr [6] in partition [0]
[DEBUG] [06/18/2018 10:52:22.772] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query took [6] ms (empty)
[DEBUG] [06/18/2018 10:52:22.772] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query from seqNr [6] in partition [1]
[DEBUG] [06/18/2018 10:52:22.790] [sys-cassandra-plugin-default-dispatcher-17] [EventsByPersistenceIdStage(akka://sys)] EventsByPersistenceId [c6031a8a-db71-4dcb-9d4f-f140faa2f4c4] Query took [17] ms (empty)
And it keeps going for ever.
I have also tried omitting the Source.fromFutureSource and just running journalQuery.eventsByPersistenceId with the same results.
What am I doing wrong?
