Streaming text lines from multiple source files - akka-stream

Question

I'm implementing a solution using akka-stream to read text lines from multiple files and came up with below impl:
def main(args: Array[String]): Unit = {
val g: Flow[String, Unit, NotUsed] = Flow.fromGraph(GraphDSL.create() {
implicit builder =>
import GraphDSL.Implicits._
val A = builder.add(doQuery)
val B = builder.add(analyzeResult)
A ~> B
FlowShape(A.in, B.out)
})
val files = Source(fileNames)
val lines = files.map(file =>
Source.fromIterator(() => Source.fromFile(file.getName, "UTF-8").getLines)
)
val done = lines.runForeach(g.runWith(_, Sink.ignore))
// implicit val ec = system.dispatcher
// done.onComplete(_ => system.terminate())
}
val fileNames: List[File] = ???
val doQuery = Flow[String]
.groupedWithin(1000, 100 millisecond)
.mapAsync(4)(x =>
Future[Seq[String]] {
synchronized {
// Do Something
Nil
}
}
)
val analyzeResult: Flow[Seq[String], Unit, NotUsed] = ???
Anyone can give comments/ feedbacks if there are better solutions?
I'd prefer not to have two Source's (the file list and the second one for the text lines from each file). Wondering how to just have one single Source (the list of files)...
TIA!

Answer 1

val g: Flow[File, Unit, NotUsed] = Flow.fromGraph(
GraphDSL.create() {
implicit builder =>
import GraphDSL.Implicits._
val A = builder.add(Flow[File]
.flatMapConcat {
Source.fromIterator(() =>
scala.io.Source.fromFile(s"${file.getAbsolutePath}", "UTF-8").getLines)
}
)
val B = builder.add(doQuery)
val C = builder.add(analyzeResult)
A ~> B ~> C
FlowShape(A.in, C.out)
}
)
val files = Source(fileNames)
val (_: NotUsed, done: Future[Done]) = g.runWith(files, Sink.ignore)
implicit val ec = system.dispatcher
done.onComplete(_ => system.terminate())