架构师 1 期 - 技术选型 (一) 作业

module ConsistentHashing  class VirtualPoint    attr_reader :node, :index
    def initialize(node, index)      @node = node      @index = index.to_i    end
    def index=(index)      @index = index.to_i    end  endend

module ConsistentHashing
  class Ring
    def initialize(nodes = [], replicas = 3)      @replicas = replicas      @ring = AVLTree.new
      nodes.each { |node| add(node) }    end
    def add(node)      @replicas.times do |i|        key = hash_key(node, i)        @ring[key] = VirtualPoint.new(node, key)      end    end
    def delete(node)      @replicas.times do |i|        key = hash_key(node, i)        @ring.delete key      end    end
    def point_for(key)      return nil if @ring.empty?      key = hash_key(key)      _, value = @ring.next_gte_pair(key)      _, value = @ring.minimum_pair unless value      value    end
    def node_for(key)      point_for(key).node    end
    protected
    def hash_key(key, index = nil)      key = "#{key}:#{index}" if index      Digest::MD5.hexdigest(key.to_s)[0..16].hex    end  endend

require 'consistent_hashing'require 'descriptive_statistics'
servers = [](0..9).each do |i|  servers << "192.168.1.10#{i}"end
(1..20).each do |time|  h_count = {}  ring = ConsistentHashing::Ring.new(servers, time)  (1..1000000).each do |i|    n = "n#{i}"    server = ring.node_for(n)    if h_count[server].nil?      h_count[server] = 1    else      h_count[server] += 1    end  end  puts ring.points.size  puts h_count.values.standard_deviationend