Optimize contributor membership retrieval

After the recent changes page rendering became significnatly slower,
because we executed many different SQL queries just to determine the
contributor status of a single participant.

This commit optimizes this by retrieving all required contributor
memberships in a single query.

Author: dutow

app/models/alias.rb

@@ -38,37 +38,45 @@ def contributor
   }.freeze
 
   def contributor?
-    person&.contributor_memberships&.exists?
+    contributor_membership_types.any?
   end
 
   def contributor_type
-    return nil unless person
-    types = person.contributor_memberships.pluck(:contributor_type)
+    types = contributor_membership_types
+    return nil if types.empty?
+
     types.min_by { |t| CONTRIBUTOR_RANK[t] || 99 }
   end
 
   def core_team?
-    person&.contributor_memberships&.core_team&.exists?
+    contributor_membership_types.include?('core_team')
   end
 
   def committer?
-    person&.contributor_memberships&.committer&.exists?
+    contributor_membership_types.include?('committer')
   end
 
   def past_contributor?
-    person&.contributor_memberships&.where(contributor_type: %w[past_major_contributor past_significant_contributor])&.exists?
+    types = contributor_membership_types
+    types.include?('past_major_contributor') || types.include?('past_significant_contributor')
   end
 
   def current_contributor?
     contributor? && !past_contributor?
   end
 
   def major_contributor?
-    person&.contributor_memberships&.major_contributor&.exists?
+    contributor_membership_types.include?('major_contributor')
   end
 
   def significant_contributor?
-    person&.contributor_memberships&.significant_contributor&.exists?
+    contributor_membership_types.include?('significant_contributor')
+  end
+
+  def contributor_membership_types
+    return [] unless person
+
+    @contributor_membership_types ||= person.contributor_memberships.load.map(&:contributor_type)
   end
 
   def contributor_badge

app/models/topic.rb

@@ -19,7 +19,7 @@ def participant_aliases(limit: 10)
                             .index_by(&:sender_id)
 
     sender_ids = sender_counts.keys
-    senders_by_id = Alias.where(id: sender_ids).index_by(&:id)
+    senders_by_id = Alias.includes(person: :contributor_memberships).where(id: sender_ids).index_by(&:id)
 
     first_sender = messages.order(:created_at).first.sender
     last_sender = messages.order(:created_at).last.sender
@@ -76,10 +76,10 @@ def contributor_participants
                       .group(:sender_id)
                       .select('sender_id, COUNT(*) AS message_count, MAX(messages.created_at) AS last_at')
 
-      alias_map = Alias.includes(:person).where(id: stats.map(&:sender_id)).index_by(&:id)
+      alias_map = Alias.includes(person: :contributor_memberships).where(id: stats.map(&:sender_id)).index_by(&:id)
 
       stats.map do |row|
-        alias_record = alias_map[row.sender_id]
+      alias_record = alias_map[row.sender_id]
         next unless alias_record
 
         {