PERF: Combine avatar_lookup and primary_group_lookup into user_lookup (#10253)

These two classes were running very similar queries, which could be expensive on large topics

lib/avatar_lookup.rb

@@ -1,32 +0,0 @@
-# frozen_string_literal: true
-
-class AvatarLookup
-
-  def initialize(user_ids = [])
-    @user_ids = user_ids.tap(&:compact!).tap(&:uniq!).tap(&:flatten!)
-  end
-
-  # Lookup a user by id
-  def [](user_id)
-    users[user_id]
-  end
-
-  private
-
-  def self.lookup_columns
-    @lookup_columns ||= %i{id user_emails.email username name uploaded_avatar_id}
-  end
-
-  def users
-    @users ||= user_lookup_hash
-  end
-
-  def user_lookup_hash
-    hash = {}
-    User.joins(:user_emails)
-      .where(id: @user_ids)
-      .select(AvatarLookup.lookup_columns)
-      .each { |user| hash[user.id] = user }
-    hash
-  end
-end

lib/plugin/instance.rb

@@ -192,8 +192,8 @@ class Plugin::Instance
 
   def custom_avatar_column(column)
     reloadable_patch do |plugin|
-      AvatarLookup.lookup_columns << column
-      AvatarLookup.lookup_columns.uniq!
+      UserLookup.lookup_columns << column
+      UserLookup.lookup_columns.uniq!
     end
   end
 

lib/primary_group_lookup.rb

@@ -1,41 +0,0 @@
-# frozen_string_literal: true
-
-class PrimaryGroupLookup
-  def initialize(user_ids = [])
-    @user_ids = user_ids.tap(&:compact!).tap(&:uniq!).tap(&:flatten!)
-  end
-
-  # Lookup primary group for a given user id
-  def [](user_id)
-    users[user_id]
-  end
-
-  private
-
-  def self.lookup_columns
-    @lookup_columns ||= %i{id name flair_icon flair_upload_id flair_bg_color flair_color}
-  end
-
-  def users
-    @users ||= user_lookup_hash
-  end
-
-  def user_lookup_hash
-    users_with_primary_group = User.where(id: @user_ids)
-      .where.not(primary_group_id: nil)
-      .select(:id, :primary_group_id)
-
-    group_lookup = {}
-    group_ids = users_with_primary_group.map(&:primary_group_id)
-    group_ids.uniq!
-
-    Group.includes(:flair_upload).where(id: group_ids).select(self.class.lookup_columns)
-      .each { |g| group_lookup[g.id] = g }
-
-    hash = {}
-    users_with_primary_group.each do |u|
-      hash[u.id] = group_lookup[u.primary_group_id]
-    end
-    hash
-  end
-end

lib/topic_query.rb

@@ -433,16 +433,14 @@ class TopicQuery
         user_ids << ft.user_id << ft.last_post_user_id << ft.featured_user_ids << ft.allowed_user_ids
       end
 
-      avatar_lookup = AvatarLookup.new(user_ids)
-      primary_group_lookup = PrimaryGroupLookup.new(user_ids)
+      user_lookup = UserLookup.new(user_ids)
 
       # memoize for loop so we don't keep looking these up
       translations = TopicPostersSummary.translations
 
       topics.each do |t|
         t.posters = t.posters_summary(
-          avatar_lookup: avatar_lookup,
-          primary_group_lookup: primary_group_lookup,
+          user_lookup: user_lookup,
           translations: translations
         )
       end

lib/user_lookup.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+class UserLookup
+
+  def initialize(user_ids = [])
+    @user_ids = user_ids.tap(&:compact!).tap(&:uniq!).tap(&:flatten!)
+  end
+
+  # Lookup a user by id
+  def [](user_id)
+    users[user_id]
+  end
+
+  def primary_groups
+    @groups ||= group_lookup_hash
+  end
+
+  private
+
+  def self.lookup_columns
+    @user_lookup_columns ||= %i{id username name uploaded_avatar_id primary_group_id}
+  end
+
+  def self.group_lookup_columns
+    @group_lookup_columns ||= %i{id name flair_icon flair_upload_id flair_bg_color flair_color}
+  end
+
+  def users
+    @users ||= user_lookup_hash
+  end
+
+  def user_lookup_hash
+    hash = {}
+    User.where(id: @user_ids)
+      .select(self.class.lookup_columns)
+      .each { |user| hash[user.id] = user }
+    hash
+  end
+
+  def group_lookup_hash
+    users_with_primary_group = users.values.reject { |u| u.primary_group_id.nil? }
+
+    group_lookup = {}
+    group_ids = users_with_primary_group.map { |u| u.primary_group_id }
+    group_ids.uniq!
+
+    Group.includes(:flair_upload)
+      .where(id: group_ids)
+      .select(self.class.group_lookup_columns)
+      .each { |g| group_lookup[g.id] = g }
+
+    hash = {}
+    users_with_primary_group.each do |u|
+      hash[u.id] = group_lookup[u.primary_group_id]
+    end
+    hash
+  end
+
+end