Optimize topics#show queries

This corrected AR usage / eager loading so we execute less actual sql
queries, speeding up the rendering time

Author: dutow

app/controllers/topics_controller.rb

@@ -36,27 +36,28 @@ def new_topics_count
   end
 
   def show
-    messages_scope = @topic.messages.includes(
-      :attachments,
-      :sender,
-      :sender_person,
-      { sender_person: :default_alias },
-      {
-        reply_to: [
-          :sender,
-          :sender_person,
-          { sender_person: :default_alias }
-        ]
-      }
-    )
+    messages_scope = @topic.messages
+      .eager_load(
+        :sender,
+        :sender_person,
+        { sender_person: :default_alias },
+        {
+          reply_to: [
+            :sender,
+            :sender_person,
+            { sender_person: :default_alias }
+          ]
+        }
+      )
+      .preload(:attachments)
 
     @messages = messages_scope.order(created_at: :asc)
     @message_numbers = @messages.each_with_index.to_h { |msg, idx| [msg.id, idx + 1] }
     preload_read_state!
     auto_mark_aware!
 
     build_participants_sidebar_data(messages_scope)
-    build_thread_outline(messages_scope)
+    build_thread_outline(@messages)
     load_commitfest_sidebar
     if user_signed_in?
       load_notes
@@ -324,17 +325,17 @@ def build_participants_sidebar_data(_messages_scope)
 
       {
         alias: alias_record,
+        person: tp.person,
         message_count: tp.message_count,
         first_at: tp.first_message_at,
         last_at: tp.last_message_at
       }
     end.compact
   end
 
-  def build_thread_outline(messages_scope)
-    ordered_messages = messages_scope.order(:created_at)
+  def build_thread_outline(messages)
     children = Hash.new { |h, k| h[k] = [] }
-    ordered_messages.each do |msg|
+    messages.each do |msg|
       children[msg.reply_to_id] << msg
     end
 

app/views/topics/_message.html.slim

@@ -26,9 +26,9 @@
         - profile_path = message.sender_person ? person_path(display_alias.email) : nil
         - if profile_path
           = link_to profile_path, class: "author-avatar-link" do
-            = image_tag display_alias.display_gravatar_url(size: 42), class: "message-avatar", alt: display_alias.name
+            = image_tag display_alias.gravatar_url(size: 42), class: "message-avatar", alt: display_alias.name
         - else
-          = image_tag display_alias.display_gravatar_url(size: 42), class: "message-avatar", alt: display_alias.name
+          = image_tag display_alias.gravatar_url(size: 42), class: "message-avatar", alt: display_alias.name
         .author-details
           - if profile_path
             .author-name = link_to display_alias.name, profile_path, class: "author-name-link"

app/views/topics/show.html.slim

@@ -124,7 +124,7 @@
                       .outline-avatars
                         - participants.each do |participant|
                           = link_to person_path(participant.email), class: "outline-avatar-link" do
-                            = image_tag participant.display_gravatar_url(size: 24), class: "outline-avatar", alt: participant.name, title: participant.name
+                            = image_tag participant.gravatar_url(size: 24), class: "outline-avatar", alt: participant.name, title: participant.name
                       - if is_reply
                         span.outline-icon ↳
                       span.branch-toggle = "▸"
@@ -142,7 +142,7 @@
                     .outline-content
                       .outline-meta
                         span.outline-number = "##{entry[:message_number]}"
-                        = image_tag msg_display.display_gravatar_url(size: 32), class: "outline-avatar", alt: msg_display.name
+                        = image_tag msg_display.gravatar_url(size: 32), class: "outline-avatar", alt: msg_display.name
                         - if is_reply
                           span.outline-icon ↳
                         span.outline-author = msg_display.name
@@ -161,7 +161,7 @@
                   .outline-content
                     .outline-meta
                       span.outline-number = "##{entry[:message_number]}"
-                      = image_tag msg_display.display_gravatar_url(size: 32), class: "outline-avatar", alt: msg_display.name
+                      = image_tag msg_display.gravatar_url(size: 32), class: "outline-avatar", alt: msg_display.name
                       - if is_reply
                         span.outline-icon ↳
                       span.outline-author = msg_display.name