class Capybara::Poltergeist::WebSocketServer
This is a 'custom' Web Socket server that is designed to be synchronous. What this means is that it sends a message, and then waits for a response. It does not expect to receive a message at any other time than right after it has sent a message. So it is basically operating a request/response cycle (which is not how Web Sockets are usually used, but it's what we want here, as we want to send a message to PhantomJS and then wait for it to respond).
Constants
- BIND_TIMEOUT
How many seconds to try to bind to the port for before failing
- HOST
- RECV_SIZE
How much to try to read from the socket at once (it's kinda arbitrary because we just keep reading until we've received a full frame)
Attributes
Public Class Methods
# File lib/capybara/poltergeist/web_socket_server.rb, line 24 def initialize(port = nil, timeout = nil) @timeout = timeout @server = start_server(port) @receive_mutex = Mutex.new end
Public Instance Methods
Accept a client on the TCP server socket, then receive its initial HTTP request and use that to initialize a Web Socket.
# File lib/capybara/poltergeist/web_socket_server.rb, line 53 def accept @socket = server.accept @messages = {} @driver = ::WebSocket::Driver.server(self) @driver.on(:connect) { |event| @driver.start } @driver.on(:message) do |event| command_id = JSON.load(event.data)['command_id'] @messages[command_id] = event.data end end
Closing sockets separately as `close_read`, `close_write` causes IO mistakes on JRuby, using just `close` fixes that.
# File lib/capybara/poltergeist/web_socket_server.rb, line 103 def close [server, socket].compact.each(&:close) end
# File lib/capybara/poltergeist/web_socket_server.rb, line 47 def connected? !socket.nil? end
Block until the next message is available from the Web Socket. Raises Errno::EWOULDBLOCK if timeout is reached.
# File lib/capybara/poltergeist/web_socket_server.rb, line 71 def receive(cmd_id) start = Time.now until @messages.has_key?(cmd_id) raise Errno::EWOULDBLOCK if (Time.now - start) >= timeout if @receive_mutex.try_lock begin IO.select([socket], [], [], timeout) or raise Errno::EWOULDBLOCK data = socket.recv(RECV_SIZE) break if data.empty? driver.parse(data) ensure @receive_mutex.unlock end else sleep(0.05) end end @messages.delete(cmd_id) end
Send a message and block until there is a response
# File lib/capybara/poltergeist/web_socket_server.rb, line 93 def send(cmd_id, message) accept unless connected? driver.text(message) receive(cmd_id) rescue Errno::EWOULDBLOCK raise TimeoutError.new(message) end
# File lib/capybara/poltergeist/web_socket_server.rb, line 30 def start_server(port) time = Time.now begin TCPServer.open(HOST, port || 0).tap do |server| @port = server.addr[1] end rescue Errno::EADDRINUSE if (Time.now - time) < BIND_TIMEOUT sleep(0.01) retry else raise end end end
# File lib/capybara/poltergeist/web_socket_server.rb, line 65 def write(data) @socket.write(data) end