Fix #16 - Optimize n+1 queries when checking reblogged/favourited values for status lists in API

app/controllers/api/v1/accounts_controller.rb

@@ -25,6 +25,7 @@ class Api::V1::AccountsController < ApiController
 
   def statuses
     @statuses = @account.statuses.with_includes.with_counters.paginate_by_max_id(20, params[:max_id], params[:since_id]).to_a
+    set_maps(@statuses)
   end
 
   def follow
@@ -53,7 +54,7 @@ class Api::V1::AccountsController < ApiController
 
   def relationships
     ids = params[:id].is_a?(Enumerable) ? params[:id].map(&:to_i) : [params[:id].to_i]
-    @accounts    = Account.find(ids)
+    @accounts    = Account.where(id: ids).select('id')
     @following   = Account.following_map(ids, current_user.account_id)
     @followed_by = Account.followed_by_map(ids, current_user.account_id)
     @blocking    = Account.blocking_map(ids, current_user.account_id)

app/controllers/api/v1/statuses_controller.rb

@@ -10,6 +10,7 @@ class Api::V1::StatusesController < ApiController
     @status      = Status.find(params[:id])
     @ancestors   = @status.ancestors
     @descendants = @status.descendants
+    set_maps([@status] + @ancestors + @descendants)
   end
 
   def create
@@ -46,16 +47,19 @@ class Api::V1::StatusesController < ApiController
 
   def home
     @statuses = Feed.new(:home, current_user.account).get(20, params[:max_id], params[:since_id]).to_a
+    set_maps(@statuses)
     render action: :index
   end
 
   def mentions
     @statuses = Feed.new(:mentions, current_user.account).get(20, params[:max_id], params[:since_id]).to_a
+    set_maps(@statuses)
     render action: :index
   end
 
   def public
     @statuses = Status.as_public_timeline(current_user.account).paginate_by_max_id(20, params[:max_id], params[:since_id]).to_a
+    set_maps(@statuses)
     render action: :index
   end
 end

app/controllers/api_controller.rb

@@ -35,4 +35,10 @@ class ApiController < ApplicationController
   def render_empty
     render json: {}, status: 200
   end
+
+  def set_maps(statuses)
+    status_ids      = statuses.flat_map { |s| [s.id, s.reblog_of_id] }.compact
+    @reblogs_map    = Status.reblogs_map(status_ids, current_user.account)
+    @favourites_map = Status.favourites_map(status_ids, current_user.account)
+  end
 end

app/models/account.rb

@@ -48,6 +48,8 @@ class Account < ApplicationRecord
   scope :with_followers, -> { where('(select count(f.id) from follows as f where f.target_account_id = accounts.id) > 0') }
   scope :expiring, -> (time) { where(subscription_expires_at: nil).or(where('subscription_expires_at < ?', time)).remote.with_followers }
 
+  scope :with_counters, -> { select('accounts.*, (select count(f.id) from follows as f where f.target_account_id = accounts.id) as followers_count, (select count(f.id) from follows as f where f.account_id = accounts.id) as following_count, (select count(s.id) from statuses as s where s.account_id = accounts.id) as statuses_count') }
+
   def follow!(other_account)
     active_relationships.where(target_account: other_account).first_or_create!(target_account: other_account)
   end

app/models/follow_suggestion.rb

@@ -22,7 +22,7 @@ END
 
     account_ids  = results['data'].map(&:first)
     blocked_ids  = Block.where(account_id: for_account_id).pluck(:target_account_id)
-    accounts_map = Account.where(id: account_ids - blocked_ids).map { |a| [a.id, a] }.to_h
+    accounts_map = Account.where(id: account_ids - blocked_ids).with_counters.map { |a| [a.id, a] }.to_h
 
     account_ids.map { |id| accounts_map[id] }.compact
   rescue Neography::NeographyError, Excon::Error::Socket => e

app/models/status.rb

@@ -2,7 +2,7 @@ class Status < ApplicationRecord
   include Paginable
   include Streamable
 
-  belongs_to :account, inverse_of: :statuses
+  belongs_to :account, -> { with_counters }, inverse_of: :statuses
 
   belongs_to :thread, foreign_key: 'in_reply_to_id', class_name: 'Status', inverse_of: :replies
   belongs_to :reblog, foreign_key: 'reblog_of_id', class_name: 'Status', inverse_of: :reblogs
@@ -90,11 +90,11 @@ class Status < ApplicationRecord
   end
 
   def self.favourites_map(status_ids, account_id)
-    Favourite.where(status_id: status_ids).where(account_id: account_id).map { |f| [f.status_id, true] }.to_h
+    Favourite.select('status_id').where(status_id: status_ids).where(account_id: account_id).map { |f| [f.status_id, true] }.to_h
   end
 
   def self.reblogs_map(status_ids, account_id)
-    where(reblog_of_id: status_ids).where(account_id: account_id).map { |s| [s.reblog_of_id, true] }.to_h
+    select('reblog_of_id').where(reblog_of_id: status_ids).where(account_id: account_id).map { |s| [s.reblog_of_id, true] }.to_h
   end
 
   before_validation do

app/views/api/v1/accounts/show.rabl

@@ -5,6 +5,6 @@ attributes :id, :username, :acct, :display_name, :note
 node(:url)             { |account| TagManager.instance.url_for(account) }
 node(:avatar)          { |account| full_asset_url(account.avatar.url(:large, false)) }
 node(:header)          { |account| full_asset_url(account.header.url(:medium, false)) }
-node(:followers_count) { |account| account.followers.count }
+node(:followers_count) { |account| account.try(:followers_count) || account.followers.count }
-node(:following_count) { |account| account.following.count }
+node(:following_count) { |account| account.try(:following_count) || account.following.count }
-node(:statuses_count)  { |account| account.statuses.count  }
+node(:statuses_count)  { |account| account.try(:statuses_count)  || account.statuses.count  }

app/views/api/v1/statuses/show.rabl

@@ -6,8 +6,8 @@ node(:content)          { |status| Formatter.instance.format(status) }
 node(:url)              { |status| TagManager.instance.url_for(status) }
 node(:reblogs_count)    { |status| status.reblogs_count }
 node(:favourites_count) { |status| status.favourites_count }
-node(:favourited, if: proc { !current_account.nil? }) { |status| current_account.favourited?(status) }
+node(:favourited, if: proc { !current_account.nil? }) { |status| defined?(@favourites_map) ? !!@favourites_map[status.id] : current_account.favourited?(status) }
-node(:reblogged,  if: proc { !current_account.nil? }) { |status| current_account.reblogged?(status) }
+node(:reblogged,  if: proc { !current_account.nil? }) { |status| defined?(@reblogs_map)    ? !!@reblogs_map[status.id]    : current_account.reblogged?(status) }
 
 child :reblog => :reblog do
   extends('api/v1/statuses/show')