forbidden_project_ids.rb

  # this is to speed up secure Project.find
  def self.forbidden_project_ids
    # Admins don't have forbidden projects
    return [0] if User.current && User.current.is_admin?

    # This will cache and return an array:
    # {projecs: [p1,p2], whitelist: { u1: [p1], u2: [p1,p2], u3: [p2] } }
    forbidden_projects = Rails.cache.fetch('forbidden_projects') do
      forbidden_projects_hash = {projects: [], whitelist: {}}
      Relationship.find_by_sql("SELECT ur.project_id, ur.user_id from flags f,
                relationships ur where f.flag = 'access' and f.status = 'disable' and ur.project_id = f.project_id").each do |r|
        forbidden_projects_hash[:projects] << r.project_id
        forbidden_projects_hash[:whitelist][r.user_id] ||= []
        forbidden_projects_hash[:whitelist][r.user_id] << r.project_id if r.user_id
      end
      forbidden_projects_hash[:projects].uniq!
      forbidden_projects_hash[:projects] << 0 if forbidden_projects_hash[:projects].empty?
      forbidden_projects_hash
    end
    # We don't need to check the relationships if we don't have a User
    return forbidden_project[:projects] if User.current.nil? || User.current.is_nobody?
    # 'cache_sequence_for_forbidden_projects' is for invalidating forbidden projects by users cache entries
    cache_sequence = Rails.cache.fetch('cache_sequence_for_forbidden_projects') || 0
    Rails.cache.fetch("users/#{User.current.id}-forbidden_projects-#{cache_sequence}") do
      # Normal users can be in the whitelist then we substract allowed projects
      whitelistened_projects_for_user = forbidden_project[:whitelist][User.current.id] || []
      result  = forbidden_project[:projects] - whitelistened_projects_for_user
    end
  end

  def self.discard_cache
    # 'cache_sequence_for_forbidden_projects' is for invalidating forbidden projects by users cache entries
    # just increasing the sequence whe you want to discard those entries
    new_cache_sequence = Rails.cache.fetch('cache_sequence_for_forbidden_projects') { 0 } + 1
    Rails.cache.write('cache_sequence_for_forbidden_projects', new_cache_sequence)
    Rails.cache.delete(FORBIDDEN_PROJECT_IDS_CACHE_KEY)
    User.current.discard_cache if User.current
  end