Balancing the server load

Question

I've created a program that will take, a bunch of numbers from a range of 1 - 255, and then put them into 3 different strings(servers) equally. It does this by having a count that starts at 1 and loops to 3, once the count has hit 3 it restarts until three servers have hit a max capacity of 100 numbers within it.

Once that max capacity has been hit, the numbers dump the remaining into a server called failsafe.

I'm looking for better ways to write this, that are cleaner, and will make this, if possible, more readable.

#!/local/usr/bin/ruby

users = (1..255) #<= Amount of users

calculon = " " #<= Random servers to be append into
darth = " "
invader_zim = " "     
failsafe = " " #<= Failsafe

count = 1
users.each do |i|
  target_string = case count
   when 1 then calculon #<= Append into server
   when 2 then darth #<= Append into server
   when 3 then invader_zim #<= Append into server
  end

  target_string = failsafe if target_string.length == 100
  target_string << i #<= When amount is reached hits fail safe

  if count == 3
    count = 1
  else
    count += 1
  end
end


puts calculon.length == 1    ? 'No users on server' : calculon.length
puts darth.length == 1       ? 'No users on server' : darth.length
puts invader_zim.length == 1 ? 'No users on server' : invader_zim.length
puts failsafe.length == 1    ? 'No users on server' : failsafe.length

Example of usage:

86
86
86
No users on server

The main objective of this program is to have a script that will equally load three different servers, and if all servers have hit a max capacity, will load into a fail safe server.

Answer 1

This is perfect use case for group_by, which basically does all the work for you in a single line:

We also get the added benefit of having the user ids as arrays instead of strings. This makes more sense, and if for some reason you do want to get the string representation back, you can simply call join(' ') on the array of user ids.

Finally, if you add more servers to your cluster, you just need to edit the single line defining the server names at the top of the file, and everything will still work.

users = (1..255) #<= Amount of users
servers = %w(calculon darth invader_zim)
server_capacity = 100

assigned_users = users.group_by.with_index do |u, i| 
  all_servers_full = (i >= servers.size * server_capacity)
  all_servers_full ? 'failsafe' : servers[i % servers.size]
end

assigned_users.each do |server, users|
  puts "#{server} server has #{users.size} users"
end

Answer 2

In this code-snippet you've 1xcase and 2xif/else statements. It's better to use ruby iterators (like with_index, with_object). This way you're avoiding unnecessary variables and their "manual" incrementing (count in your case). Also try to avoid unexplained "hard-coded" integers(3, 100). Basically they're variables or constants.

Next weird strings... it's hard to understand their purpose. Why use " ", not empty string? Everywhere in code string length is used, not content.

Output lines can be easily organized with each and be more informative.

My variant of your code refactoring:

users = (1..255)

servers = Array.new(3, 0)
failsafe = 0
max_load = 100


users.each.with_index do |i, index|
  current = index%servers.count
  if servers[current] < max_load
  then servers[current] += 1
  else failsafe += 1
  end
end

server_list = servers + [failsafe]
%w(calculon darth invader_zim failsafe).each.with_index do |name, index|
  p "On '#{name}' server currently #{server_list[index] == 0 ? 'NO' : server_list[index]} users."
end