Akka Java文件IO限制

Question

I want to stream file content line by line to Actor. I have something like that:

final ActorSystem system = ActorSystem.create("stream_system");
final Materializer materializer = ActorMaterializer.create(system);
final ActorRef actor = system.actorOf(Props.create(streamActor.class), "sink");

final Path file = Paths.get("path/file.txt");

Sink<ByteString, CompletionStage<Done>> printlnSink =
        Sink.<ByteString> foreach(chunk -> actor.tell(chunk.utf8String(), null));
        //Sink.<ByteString> actorRef(actor, null);

CompletionStage<IOResult> ioResult =
        FileIO.fromPath(file)
                .throttle(1, Duration.create(1, TimeUnit.SECONDS), 1, ThrottleMode.shaping())
                .to(printlnSink)
                .run(materializer);

Uncommented version works, but it streams whole file content in one go. Commented version ends up with "unknown" messages.

I want to send line by line to Actor with few seconds delay. Any help how to accomplish this? Receiving actor just take String message and print it on output.

Answer 1

The Framing class can help you with this:

CompletionStage<IOResult> ioResult =
    FileIO.fromPath(file)
          .via(Framing.delimiter(ByteString.fromString(System.lineSeparator()), 1000, FramingTruncation.ALLOW))
          .throttle(1, Duration.create(1, TimeUnit.SECONDS), 1, ThrottleMode.shaping())
          .to(printlnSink)
          .run(materializer);