New job (default off) to detect whether users have uploaded custom avatars by contacting Gravatar.

app/models/site_setting.rb

@@ -254,6 +254,9 @@ class SiteSetting < ActiveRecord::Base
   client_setting(:allow_uploaded_avatars, true)
   client_setting(:allow_animated_avatars, false)
 
+  setting(:detect_custom_avatars, false)
+  setting(:max_daily_gravatar_crawls, 500)
+
   def self.generate_api_key!
     self.api_key = SecureRandom.hex(32)
   end

config/locales/server.en.yml

@@ -672,6 +672,10 @@ en:
     allow_animated_avatars: "Allow users to use animated gif for avatars. WARNING: it is highly recommended to run the avatars:regenerate rake task after changing that setting."
     default_digest_email_frequency: "How often users receive digest emails by default. They can change this setting in their preferences."
 
+    detect_custom_avatars: "Whether or not to check that users have uploaded custom avatars"
+    max_daily_gravatar_crawls: "The maximum amount of times Discourse will check gravatar for custom avatars in a day"
+
+
   notification_types:
     mentioned: "%{display_username} mentioned you in %{link}"
     liked: "%{display_username} liked your post in %{link}"

lib/jobs/detect_avatars.rb

@@ -0,0 +1,26 @@
+require_dependency 'avatar_detector'
+
+module Jobs
+
+  class DetectAvatars < Jobs::Scheduled
+    recurrence { daily.hour_of_day(8) }
+
+    def execute(args)
+      return unless SiteSetting.detect_custom_avatars?
+
+      # Find a random sampling of users of trust level 1 or higher who don't have a custom avatar.
+      user_stats = UserStat.where('user_stats.has_custom_avatar = false AND users.trust_level > 0')
+                           .includes(:user)
+                           .order("random()")
+                           .limit(SiteSetting.max_daily_gravatar_crawls)
+
+      if user_stats.present?
+        user_stats.each do |us|
+          us.update_column(:has_custom_avatar, true) if AvatarDetector.new(us.user).has_custom_avatar?
+        end
+      end
+    end
+
+  end
+
+end