optimised welcome page load time:

- optimized surprise author fetching
- optimized fetching of text totals by periods
- optimized fetching of authors totals by genres

app/controllers/application_controller.rb

@@ -152,10 +152,14 @@ def randomize_works(how_many)
   end
 
   def cached_authors_in_genre
-    Rails.cache.fetch("au_by_genre", expires_in: 24.hours) do # memoize
-      ret = {}
-      get_genres.each { |g| ret[g] = Person.has_toc.joins(expressions: :work).where(works: { genre: g }).uniq.count }
-      ret
+    Rails.cache.fetch('au_by_genre', expires_in: 24.hours) do # memoize
+      totals = Person.has_toc
+                     .joins(expressions: :work)
+                     .group(:genre)
+                     .distinct
+                     .count
+                     .to_h
+      get_genres.index_with { |genre| totals[genre] || 0 }
     end
   end
 
@@ -168,10 +172,9 @@ def cached_authors_in_period
   end
 
   def cached_works_by_period
-    Rails.cache.fetch("works_by_period", expires_in: 24.hours) do # memoize
-      ret = {}
-      get_periods.each{ |p| ret[p] = Manifestation.published.joins(:expression).where(expressions: { period: p}).uniq.count}
-      ret
+    Rails.cache.fetch('works_by_period', expires_in: 24.hours) do # memoize
+      totals = Manifestation.published.joins(:expression).group(:period).count
+      get_periods.index_with { |period| totals[Expression.periods[period]] || 0 }
     end
   end
 

app/controllers/authors_controller.rb

@@ -4,6 +4,7 @@
 
 class AuthorsController < ApplicationController
   include FilteringAndPaginationConcern
+  include AuthorsHelper
 
   before_action only: [:new, :publish, :create, :show, :edit, :list, :add_link, :delete_link, :delete_photo, :edit_toc, :update, :to_manual_toc] do |c| c.require_editor('edit_people') end
   autocomplete :tag, :name, :limit => 2
@@ -35,17 +36,16 @@ def publish
   end
 
   def get_random_author
-    rel = Person.has_toc.
-        joins(creations: { work: { expressions: :manifestations } }).
-        merge(Manifestation.published).
-        merge(Creation.author)
-
     genre = params[:genre]
-    if genre.present?
-      rel = rel.where(works: { genre: genre })
-    end
-    @author = rel.distinct.order(Arel.sql('rand()')).first
-    render partial: 'shared/surprise_author', locals: {author: @author, initial: false, id_frag: params[:id_frag], passed_genre: genre, passed_mode: params[:mode], side: params[:side]}
+    render partial: 'shared/surprise_author',
+           locals: {
+             author: random_author(genre),
+             initial: false,
+             id_frag: params[:id_frag],
+             passed_genre: genre,
+             passed_mode: params[:mode],
+             side: params[:side]
+           }
   end
 
   def delete_photo

app/controllers/welcome_controller.rb

@@ -1,6 +1,7 @@
 include BybeUtils
 class WelcomeController < ApplicationController
-#  impressionist # log actions for pageview stats
+  #  impressionist # log actions for pageview stats
+  include AuthorsHelper
 
   def index
     @tabclass = set_tab('home')
@@ -14,7 +15,7 @@ def index
     # @newest_authors = cached_newest_authors # deprecated because we stopped producing portraits
     @random_authors = Person.published.has_image.order(Arel.sql('RAND()')).limit(10)
     @newest_works = cached_newest_works
-    @surprise_author = Person.where(id: Person.has_toc.pluck(:id).sample(1))[0]
+    @surprise_author = random_author
     @surprise_work = randomize_works(1)[0]
     @authors_in_genre = cached_authors_in_genre
     @works_by_genre = Manifestation.cached_work_counts_by_genre

app/helpers/authors_helper.rb

@@ -37,4 +37,25 @@ def browse_upload_date(item)
   def browse_null_decorator(item)
     return ''
   end
-end
+
+  def random_author(genre = nil)
+    relation = Person.has_toc
+                     .where(
+                       <<~SQL.squish,
+                         exists (
+                           select 1 from
+                             creations c
+                             join works w on (c.work_id = w.id)
+                             join expressions e on (e.work_id = w.id)
+                             join manifestations m on (m.expression_id = e.id)
+                           where
+                             m.status = ?
+                             and w.genre = coalesce(?, w.genre)
+                         )
+                       SQL
+                       Manifestation.statuses[:published],
+                       genre
+                     )
+    relation.order(Arel.sql('rand()')).first
+  end
+end