UDP Socket and Threading in API

sungamer

Hey,

I'm trying to integrate a new self developed input device into SU. The device is connected over RS232 and data is processed through an C# application.
Now I tried to send the data over UDP to SU. This is my Ruby Plugin code for testing:

require 'socket'

server = Thread.new {
	$port = 3157
	$maxSize = 100
	serverSocket = UDPSocket.new
	serverSocket.bind("127.0.0.1", $port)

	UI.messagebox("Socket open!")

	loop {
		data = serverSocket.recvfrom($maxSize)
		if data.length != 0
			UI.messagebox(data)
		end
	}

}

If I send a UDP message to this socket, i don't get a message from SU but Windows shows me, that the socket is open.
Could anybody tell me why this is not working? Thank you!

Greetings,
Patrick

Dan Rathbun

Probably because we are running embedded Ruby as a subprocess of Sketchup's process... (unlike when you run Ruby in it's own process from the command shell.)

The Sketchup application "owns" the main event loop, and controls when Ruby code actaully executes. So you need to follow the Sketchup API "rules".

Also.. Threads in Ruby 1.8.x branch do not work well in an embedded Ruby evironment.

But there is a special Sketchup API "thread-like" block method that can give you a polling type mechanism.

timer_id = UI.start_timer(delay,repeat) { #block of code }

see API doc:
UI.start_timer
and:
UI.stop_timer

mtalbott

As Dan pointed out UI.start_timer works pretty good with UDP. Here's how I'd write it:


require 'socket'
serverSocket = UDPSocket.new
serverSocket.bind("127.0.0.1", 3157)
timer_id = UI.start_timer(0.1, true) {
  begin
    data = socket.recvfrom_nonblock(100)
    new_message = true
  rescue Errno;;EWOULDBLOCK
    new_message = false
  rescue Errno;;ECONNRESET
    new_message = false
    UI.stop_timer @timer_id
    break
  end
  if new_message == true
    UI.messagebox(data)
  end
}

The major different is the UI.start_timer in place of the "Thread" and "Loop" in your example. You'll also see that it uses .recvfrom_nonblock with some error catching instead of just .recvfrom. This is because sketchup will hang if nothing is sent to the socket. If you're sure that there will be a constant stream of data you might be able to get it to work with blocking.