Directory watch - added, changed, deleted files as events

[johanandren]

Idea for a new source, I have one lying around on my computer since earlier and there was discussions on akka/akka about such a source.

I'm thinking Source[(Path, ChangeType), SomeWayToCancel] or possibly skip that SomeWayToCancel since it can be achieved by combining with a KillSwitch

[joearasin]

It's a bit of a hack, but to play around with other pieces of the system and punt the innards of this to later, I used:

  val monitor = RxMonitor()
  val observable: Observable[EventAtPath] = monitor.observable
  val publisher = RxReactiveStreams.toPublisher(JavaConversions.toJavaObservable(observable))
  val eventSource: Source[EventAtPath, NotUsed] = Source.fromPublisher(publisher)
  // Run things 
  monitor.registerPath(ENTRY_MODIFY, "/path/to/whatever")

using https://github.com/lloydmeta/schwatcher with RxReactiveStreams

[johanandren]

We also discussed pulling in https://github.com/pathikrit/better-files and use their actor based watch. But I think I'll stick to using the JDK provided WatchService (https://docs.oracle.com/javase/8/docs/api/java/nio/file/FileSystem.html#newWatchService--). It's a pretty horrible interface, but it's 0-dependencies so that is a nice thing. It should be using native OS facilities on some platforms AFAIR.