s-lib-watch_2.13.0.11.4-M3.source-code.package.scala Maven / Gradle / Ivy

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package os

package object watch {

  /**
   * Efficiently watches the given `roots` folders for changes. Any time the
   * filesystem is modified within those folders, the `onEvent` callback is
   * called with the paths to the changed files or folders.
   *
   * Once the call to `watch` returns, `onEvent` is guaranteed to receive a
   * an event containing the path for:
   *
   * - Every file or folder that gets created, deleted, updated or moved
   *   within the watched folders
   *
   * - For copied or moved folders, the path of the new folder as well as
   *   every file or folder within it.
   *
   * - For deleted or moved folders, the root folder which was deleted/moved,
   *   but *without* the paths of every file that was within it at the
   *   original location
   *
   * Note that `watch` does not provide any additional information about the
   * changes happening within the watched roots folder, apart from the path
   * at which the change happened. It is up to the `onEvent` handler to query
   * the filesystem and figure out what happened, and what it wants to do.
   */
  def watch(
      roots: Seq[os.Path],
      onEvent: Set[os.Path] => Unit,
      logger: (String, Any) => Unit = (_, _) => ()
  ): AutoCloseable = {
    val watcher = System.getProperty("os.name") match {
      case "Mac OS X" => new os.watch.FSEventsWatcher(roots, onEvent, logger, 0.05)
      case _ => new os.watch.WatchServiceWatcher(roots, onEvent, logger)
    }

    val thread = new Thread {
      override def run(): Unit = {
        watcher.run()
      }
    }
    thread.setDaemon(true)
    thread.start()
    watcher
  }
}