socket_pool.rb

class SocketPool
  def initialize
    @sockets = Hash.new { |h,k| h[k] = [] }
    @mutex = Mutex.new
  end

  def checkout(host, port)
    @mutex.synchronize do
      sockets = @sockets[host][port]

      if sockets.empty?
        TCPSocket.new(host, port)
      else
        sockets.pop
      end
    end
  end

  def checkin(socket)
    @mutex.synchronize do
      @sockets[socket.host][socket.port] << socket
    end
  end
end