Stream of File Watcher

streamwatch.scala

import java.io._
import java.nio.file._
import scala.collection.JavaConversions._

object WatchStream {

  // Watch service can watch multiple paths (as keys) but we're just using one
  // so we can ws.take and assume whatever comes back is the path we care about.
  private[this] val ws = FileSystems.getDefault.newWatchService()

  private def events(key: WatchKey): Seq[WatchEvent[_]] = {
    val es = key.pollEvents
    key.reset()
    es
  }

  // If you delete the path, the result is List(), but then NoSuchFileException during resolve
  def apply(path: Path): Stream[Seq[Path]] = {
    path.register(ws, StandardWatchEventKinds.ENTRY_CREATE)
    Option(ws.take()).toSeq.flatMap(events).map(_.context).map{case p: Path => path.resolve(p)} #:: apply(path)
  }

  // What's the best way to stop reading?
  // Would iteratee be better here?
  // flatten to Stream[Path]? ... but may be a very large list of changes?
  // seed with contents of path at start?

 }


println("Doing")

val path = Paths.get("/tmp", "wdir")
WatchStream(path).foreach(p => println(p))

println("DONE")