Reconnect on lost network

[dtonon]

Hi, which is the correct way to manage a reconnect when the connection is lost?
I tried this code:

def relay_connect(relay_host)

  ws = WebSocket::Client::Simple.connect(relay_host)

  ws.on :open do |event|
    # ....
  end

  ws.on :message do |msg|
    # ....
  end

  ws.on :error do |event|
    
    puts "Error, reconnecting..."
    sleep(5)
    ws = nil
    relay_connect(relay_host)
  end

  ws.on :close do |event|
    # p [:close, event.code, event.reason]
    puts "Reconnecting..."
    sleep(5)
    ws = nil
    relay_connect(relay_host)
  end

end

relay_connect(relay_host)

loop do
  STDIN.gets.strip
end

But it does not work.
It doesn't give any output when I block the network, while the CPU spikes up at 100%.
Any help :)

[unasuke]

while the CPU spikes up at 100%

@dtonon Which line did the CPU spiked? Could you recognize it? I tried your script on my local machine, it works and did not spike a CPU.

[dtonon]

@unasuke sorry, my fault, the previus code works because I simplified it too much.
The loop with the STDIN.gets is inside the method, and now that I note the matter it obviously creates a recursive escalation of loops, stressing the CPU.

def relay_connect(relay_host)

  ws = WebSocket::Client::Simple.connect(relay_host)

  ws.on :open do |event|
    # ....
  end

  ws.on :message do |msg|
    # ....
  end

  ws.on :error do |event|
    
    puts "Error, reconnecting..."
    sleep(5)
    ws = nil
    relay_connect(relay_host)
  end

  ws.on :close do |event|
    # p [:close, event.code, event.reason]
    puts "Reconnecting..."
    sleep(5)
    ws = nil
    relay_connect(relay_host)
  end

  loop do
    ws.send STDIN.gets.strip
  end

end

relay_connect(relay_host)

Related: when I block the network (applying a firewall rule) I cannot see any "reconnecting" output, perhaps it is somehow buffered?

[dtonon]

@unasuke even removing the ricorsive connection the hang problem remains.
I suspect that the culprit is the firewall (Little Snitch on macOS) that I use to simulate the blocked connection. As soon I deny the connection the CPU spikes at 100% and even if I remove the blocking rule the process stay stucked.
Instead if I disable the network at the system level, the CPU usage is normal and as soon I reactivate it the buffered messages are sent.
In both cases no close/error events are been generated, so the client cannot really understand that is offline.

Tested code:

require 'websocket-client-simple'

relay_host = "ws://127.0.0.1"

def relay_connect(relay_host)

  ws = WebSocket::Client::Simple.connect(relay_host)

  ws.on :open do |event|
    puts "---------- Open -----------------\n#{event.inspect}\n\n"
  end

  ws.on :message do |event|
    puts "---------- Event -----------------\n#{event.inspect}\n\n"
  end

  ws.on :error do |event|
    puts "---------- Error -----------------\n#{event.inspect}\n\n"
  end

  ws.on :close do |event|
    puts "---------- Close -----------------\n#{event.inspect}\n\n"
  end

  loop do
    ws.send STDIN.gets.strip
  end

end

relay_connect(relay_host)

[unasuke]

(Little Snitch on macOS)

It's great infomation! I tried that scripts on Ubuntu (WSL), but there is no problem.
So I guess macOS does other behavior. I will try this on macOS.