Ruby while loop only executes once with break if statement

Question

I am trying to continue while loop for 3 times. If I get data from server the loop should break. But in the below code while loop terminates after responding one time. What should I do?

@i = 0
while @i < 3
  udp_socket.send req_param[:msg], req_param[:flag], req_param[:url], req_param[:port]
    @i +=1
    puts "#{@i}"
    if udp_socket.recvfrom(100)
      break
    end
end 
  for j in 0..1
  resp = udp_socket.recvfrom(100)
  puts "resp:#{resp.inspect}"
 end
udp_socket.close
return resp

Answer 1

recvfrom(inherited from the parent IPSocket) would block until it gets data (unless nonblock option is set). Which means that it would be a non-falsy return, and break. It will always wait until there is data and break.

Perhaps you meant to non-block? - calling the recvfrom_nonblock method instead?

Answer 2

By looking at the code, it seems you're not updating resp variable inside while loop, change code to something like this instead:

j = 1
resp = udp_socket.recvfrom(100)
if resp
  udp_socket.close
  return resp
end
while j < 3
  udp_socket.send req_param[:msg], req_param[:flag], req_param[:url], req_param[:port]
  resp = udp_socket.recvfrom(100)
  j += 1
  puts "ok"
  break if resp  
end
puts "resp:#{resp.inspect}"