Usage

import akka.actor.ActorSystem
import akka.io._
import File._
import akka.util._
import akka.pattern.ask
import scala.concurrent.duration._
import java.nio.file._

implicit val timeout: Timeout = 5.seconds
implicit val system = ActorSystem("system")

import system.dispatcher

// open a file
val openRes = IO(File) ? Open(file = Paths.get("/tmp", "test-file.txt"), openOptions = StandardOpenOption.WRITE :: StandardOpenOption.READ :: StandardOpenOption.CREATE :: Nil)

val fileHandler = openRes.mapTo[Opened].map(_.handler)

// Write to the beginning of the file
val writeRes = fileHandler.flatMap(_ ? Write(ByteString("some text"), 0))

// Read 9 bytes from the beginning of the file
fileHandler.flatMap(_ ? Read(9, 0)).onSuccess {
  case ReadResult(bytes, bytesRead) => println(bytes.decodeString("utf-8"))
}

FileSlurp

A FileSlurp reads a whole file in chunks and sends them to the receiver in correct order. When the whole file has been read the FileSlurp sends a FileSlurp.Done message and shuts itself down.

val receiver: ActorRef = ...
val path = java.nio.file.Paths.get(...)

// chunkSize is optional and defaults to 256
system.actorOf(Props(classOf[FileSlurp], path, receiver, 512))