class DirectoryWatcher::EmScanner

The EmScanner uses the EventMachine reactor loop to monitor changes to files in the watched directory. This scanner is more efficient than the pure Ruby scanner because it relies on the operating system kernel notifications instead of a periodic polling and stat of every file in the watched directory (the technique used by the Scanner class).

EventMachine cannot notify us when a file is added to the watched directory; therefore, added files are only picked up when we apply the glob pattern to the directory. This is done at the configured interval.

Notes:

* Kqueue does not generate notifications when "touch" is used to update
  a file's timestamp. This applies to Mac and BSD systems.

* New files are detected only when the watched directory is polled at the
  configured interval.

Public Class Methods

new( configuration ) click to toggle source
Calls superclass method DirectoryWatcher::EventableScanner.new
# File lib/directory_watcher/em_scanner.rb, line 40
def initialize( config )
  super(config)
end

Public Instance Methods

start_loop_with_attached_scan_timer() click to toggle source

Called by EventablScanner#start to start the loop up and attach the periodic timer that will poll the globs for new files.

# File lib/directory_watcher/em_scanner.rb, line 47
def start_loop_with_attached_scan_timer
  return if @loop_thread
  unless EventMachine.reactor_running?
    @loop_thread = Thread.new {EventMachine.run}
    Thread.pass until EventMachine.reactor_running?
  end

  @timer = ScanTimer.new(self)
end
stop_loop() click to toggle source

Called by EventableScanner#stop to stop the loop as part of the shutdown process.

# File lib/directory_watcher/em_scanner.rb, line 60
def stop_loop
  if @loop_thread then
    EventMachine.next_tick do
      EventMachine.stop_event_loop
    end
    @loop_thread.kill
    @loop_thread = nil
  end
end