Class: SidebarSiteSettingsBackfiller

Inherits:
Object
  • Object
show all
Defined in:
app/services/sidebar_site_settings_backfiller.rb

Overview

A service class that backfills the changes to the default sidebar categories and tags site settings.

When a category/tag is removed from the site settings, the ‘SidebarSectionLink` records associated with the category/tag are deleted.

When a category/tag is added to the site settings, a ‘SidebarSectionLink` record for the associated category/tag are created for all users that do not already have a `SidebarSectionLink` record for the category/tag.

Instance Method Summary collapse

Constructor Details

#initialize(setting_name, previous_value:, new_value:) ⇒ SidebarSiteSettingsBackfiller

Returns a new instance of SidebarSiteSettingsBackfiller.



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# File 'app/services/sidebar_site_settings_backfiller.rb', line 11

def initialize(setting_name, previous_value:, new_value:)
  @setting_name = setting_name

  @linkable_klass, previous_ids, new_ids =
    case setting_name
    when "default_navigation_menu_categories"
      [Category, previous_value.split("|"), new_value.split("|")]
    when "default_navigation_menu_tags"
      klass = Tag

      [
        klass,
        klass.where(name: previous_value.split("|")).pluck(:id),
        klass.where(name: new_value.split("|")).pluck(:id),
      ]
    else
      raise "Invalid setting_name"
    end

  @added_ids = new_ids - previous_ids
  @removed_ids = previous_ids - new_ids
end

Instance Method Details

#backfill! ⇒ Object 



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# File 'app/services/sidebar_site_settings_backfiller.rb', line 34

def backfill!
  DistributedMutex.synchronize("backfill_sidebar_site_settings_#{@setting_name}") do
    SidebarSectionLink.where(
      linkable_type: @linkable_klass.to_s,
      linkable_id: @removed_ids,
    ).delete_all

    User
      .real
      .where(staged: false)
      .select(:id)
      .find_in_batches do |users|
        rows = []

        users.each do |user|
          @added_ids.each do |linkable_id|
            rows << {
              user_id: user[:id],
              linkable_type: @linkable_klass.to_s,
              linkable_id: linkable_id,
            }
          end
        end

        SidebarSectionLink.insert_all(rows) if rows.present?
      end
  end
end

#number_of_users_to_backfill ⇒ Object 



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# File 'app/services/sidebar_site_settings_backfiller.rb', line 63

def number_of_users_to_backfill
  select_statements = []

  select_statements.push(<<~SQL) if @removed_ids.present?
    SELECT
      sidebar_section_links.user_id
    FROM sidebar_section_links
    WHERE sidebar_section_links.linkable_type = '#{@linkable_klass.to_s}'
    AND sidebar_section_links.linkable_id IN (#{@removed_ids.join(",")})
    SQL

  if @added_ids.present?
    # Returns the ids of users that will receive the new additions by excluding the users that already have the additions
    # Note that we want to avoid doing a left outer join against the "sidebar_section_links" table as PG will end up having
    # to do a full table join for both tables first which is less efficient and can be slow on large sites.
    select_statements.push(<<~SQL)
    SELECT
      users.id
    FROM users
    WHERE users.id NOT IN (
      SELECT
        DISTINCT(sidebar_section_links.user_id)
      FROM sidebar_section_links
      WHERE sidebar_section_links.linkable_type = '#{@linkable_klass.to_s}'
      AND sidebar_section_links.linkable_id IN (#{@added_ids.join(",")})
    ) AND users.id > 0 AND NOT users.staged
    SQL
  end

  return 0 if select_statements.blank?

  DB.query_single(<<~SQL)[0]
  SELECT
    COUNT(*)
  FROM (#{select_statements.join("\nUNION DISTINCT\n")}) AS user_ids
  SQL
end