Generates a directory with X files with name length A spread by Y directories with name length A with depth Z

generator.rb

require 'securerandom'
require 'fileutils'

NUM_FILES = 35000
NUM_DIRECTORIES = 5000
NAME_LENGTH = 100
MAX_DIR_DEPTH = 10
MAX_FILES_PER_DIR = 100
MAX_DIRS_PER_DIR = 100

def random_name
  SecureRandom.hex(NAME_LENGTH / 2)
end

class GenDir
  attr_reader :parent

  def self.create
    self.new(random_name)
  end

  def initialize(name, parent = nil)
    @name = name
    @files_count = 0
    @dirs_count = 0
    @parent = parent
    FileUtils.mkdir_p(name)
  end

  def generate_file
    return false if @files_count >= MAX_FILES_PER_DIR
    File.open(File.join(@name, random_name), 'w') do |f|
      f << 'foobar'
    end
    @files_count += 1
  end

  def generate_subdir
    return false if @dirs_count >= MAX_DIRS_PER_DIR
    self.class.new(File.join(@name, random_name), self)
  end
end

directories = Enumerator.new do |y|
  num_directories = 0
  root = current = GenDir.new('.')
  y << current

  while current && num_directories < NUM_DIRECTORIES do
    if following = current.generate_subdir
      num_directories += 1
      y << following
    elsif current.parent
      y << current.parent
    else
      current = nil
    end
  end
end

cwd = directories.next
NUM_FILES.times do
  unless cwd.generate_file
    cwd = directories.next
    raise 'Ran out of directories to write files to :(' unless cwd.generate_file
  end
end