Queuing theory exercise

queuing.rb

class Node
  attr_accessor :edges, :jobs, :id

  def initialize(id, arrivals_per_tick)
    @id = id
    @jobs = 0.0
    @tick = 0
    @edges = []
    @arrivals_per_tick = arrivals_per_tick
  end

  def tick
    @tick += 1
    @jobs += @arrivals_per_tick

    if @edges.any?
      # only supports two edges
      probability, _ = @edges[0][0]
      index = nil

      [@jobs.floor, 10].min.times do
        if Kernel.rand <= probability
          index = 0
        else
          index = 1
        end

        @edges[index][1].jobs += 1.0
        # puts "Tick #{@tick}, node: #{@id}, pushed to: #{@edges[index][1].id}"
        @jobs -= 1
      end
    end
  end

  def print
    visual = "@" * [jobs, 42].min
    puts "#{visual}[ #{@id} ]"
  end
end

one = Node.new('1', 5.3)
two = Node.new('2', 1)
three = Node.new('3', 1)
sink = Node.new('sink', 0)

one.edges << [0.8, two]
one.edges << [0.2, three]

two.edges << [0.8, sink]
two.edges << [0.2, three]

three.edges << [1.0, one]

def printer(one, two, three, sink)
  ascii = <<~HEREDOC
  \e[H\e[2J
                                                     
                  ---1---->+------------+          
                           |  Server 2  ---0.8-----> #{"%03d" % sink.jobs}
           |----0.8------->|  #{"%03d" % two.jobs}       |          
           |               +------------+          
           |                         |             
    +------+-----+                   | 0.2           
 5.2|  Server 1  ---0.2----+         |             
 --->  #{"%03d" % one.jobs}       |         |         |             
    +------^-----+         |         |             
           |               |---------|--+          
           |               |  Server 3  |          
           +--1.0----------|  #{"%03d" % three.jobs}       |
                      1--->+------------+
  HEREDOC
  sleep 0.01
  puts ascii
end

1000.times do |i|
  one.tick
  printer(one, two, three, sink)
  two.tick
  printer(one, two, three, sink)
  three.tick
  printer(one, two, three, sink)
end