scope jdk_watchService_start.

static new Flag #started;

static new MultiMap<WatchKey, O> #listeners; // values: voidfunc(File)

static int #interval = 50; // larger interval helps show less duplicate events (https://stackoverflow.com/questions/16777869/java-7-watchservice-ignoring-multiple-occurrences-of-the-same-event/34818620#34818620)

static WatchService jdk_watchService_start() {

  final WatchService service = jdk_defaultWatchService();

  if (started.raise()) thread "Watch Service" {

    while licensed { 

      WatchKey key = service.poll(10, TimeUnit.SECONDS);

      if (key != null) {

        Path dir = cast key.watchable();

        sleep(interval);

        L<WatchEvent<?>> events = key.pollEvents();

        new LinkedHashSet<File> changedFiles;

        for (WatchEvent<?> event : reversedIterator(events)) pcall {

          final Path changed = (Path) event.context();

          File full = newFile(dir.toFile(), changed.toFile().getPath());

          changedFiles.add(full);

          //print("WatchService Changed: " + full + ", " + event.kind());

        }

        for (File f : changedFiles)

          pcallFAll(listeners.get(key), f);

        key.reset();

      }

    }

  }

  ret service;

}

end scope