CaDs

class User < ApplicationRecord
  has_many :posts, dependent: :destroy
  has_many :connections, dependent: :destroy

  has_many :follower_connections, foreign_key: :following_id, class_name: 'Connection'
  has_many :followers, through: :follower_connections, source: :follower

  has_many :following_connections, foreign_key: :follower_id, class_name: 'Connection'
  has_many :following, through: :following_connections, source: :following

CaDs

class Post < ApplicationRecord
  belongs_to :user

  after_create_commit :enqueue_delivery

  class << self
    def cache_key_for(id:)
      "cached_post/#{id}"
    end

CaDs

class PostsController < ApplicationController
  before_action :auth_user

  def index
    @posts = @user.fetch_feed
  end
end

class User < ApplicationRecord
  def fetch_feed

CaDs

class Connection < ApplicationRecord
  belongs_to :follower, class_name: 'User', foreign_key: :follower_id
  belongs_to :following, class_name: 'User', foreign_key: :following_id
end

CaDs

def get_partition_original(ss)
    return (ss.size == 0 ? [[[] of Int32]] : [[ss]]) if ss.size <= 1
    out = [[Array(Int32).new, Array(Int32).new]].clear
    (0...2**ss.size / 2).each { |i|
        parts = [Array(Int32).new, Array(Int32).new]
        ss.each { |item|
            parts[i&1] << item
            i >>= 1
        }
        get_partition_original(parts[1]).each { |b|