posts: micro-optimize allocations during thumbnail generation.

Do a few micro-optimizations to reduce the number of memory allocations
during thumbnail generation.

This commit, combined with freezing string literals in a7dc05 and
67b961, reduces the number of allocations on the front page from 180,000
to 150,000, and the number of retained objects from 8,000 to 4,000.

app/components/post_preview_component.rb

@@ -123,6 +123,6 @@ class PostPreviewComponent < ApplicationComponent
   end
 
   def has_sound?
-    post.has_tag?("sound")
+    is_animated? && post.has_tag?("sound")
   end
 end

app/models/media_asset.rb

@@ -4,6 +4,9 @@ class MediaAsset < ApplicationRecord
   class Error < StandardError; end
 
   VARIANTS = %i[preview crop 180x180 360x360 720x720 sample original]
+  ENABLE_SEO_POST_URLS = Danbooru.config.enable_seo_post_urls
+  LARGE_IMAGE_WIDTH = Danbooru.config.large_image_width
+  STORAGE_SERVICE = Danbooru.config.storage_manager
 
   has_one :media_metadata, dependent: :destroy
   has_one :pixiv_ugoira_frame_data, class_name: "PixivUgoiraFrameData", foreign_key: :md5, primary_key: :md5
@@ -88,7 +91,7 @@ class MediaAsset < ApplicationRecord
         "/images/download-preview.png"
       else
         slug = "__#{slug}__" if slug.present?
-        slug = nil if !Danbooru.config.enable_seo_post_urls
+        slug = nil if !ENABLE_SEO_POST_URLS
         "/#{variant}/#{md5[0..1]}/#{md5[2..3]}/#{slug}#{file_name}"
       end
     end
@@ -166,7 +169,7 @@ class MediaAsset < ApplicationRecord
       when :"720x720"
         true
       when :sample
-        media_asset.is_ugoira? || (media_asset.is_static_image? && media_asset.image_width > Danbooru.config.large_image_width)
+        media_asset.is_ugoira? || (media_asset.is_static_image? && media_asset.image_width > LARGE_IMAGE_WIDTH)
       when :original
         true
       end
@@ -271,7 +274,7 @@ class MediaAsset < ApplicationRecord
     end
 
     def storage_service
-      Danbooru.config.storage_manager
+      STORAGE_SERVICE
     end
 
     def backup_storage_service

app/models/post.rb

@@ -8,6 +8,8 @@ class Post < ApplicationRecord
   NOTE_COPY_TAGS = %w[translated partially_translated check_translation translation_request reverse_translation
                       annotated partially_annotated check_annotation annotation_request]
 
+  RESTRICTED_TAGS = Danbooru.config.restricted_tags
+
   self.ignored_columns = [:pool_string, :fav_string]
 
   deletable
@@ -292,11 +294,11 @@ class Post < ApplicationRecord
 
   module TagMethods
     def tag_array
-      @tag_array ||= tag_string.split
+      tag_string.split
     end
 
     def tag_array_was
-      @tag_array_was ||= (tag_string_in_database.presence || tag_string_before_last_save || "").split
+      (tag_string_in_database.presence || tag_string_before_last_save || "").split
     end
 
     def tags
@@ -346,7 +348,6 @@ class Post < ApplicationRecord
     end
 
     def merge_old_changes
-      reset_tag_array_cache
       @removed_tags = []
 
       if old_tag_string
@@ -380,14 +381,8 @@ class Post < ApplicationRecord
       end
     end
 
-    def reset_tag_array_cache
-      @tag_array = nil
-      @tag_array_was = nil
-    end
-
     def set_tag_string(string)
       self.tag_string = string
-      reset_tag_array_cache
     end
 
     def normalize_tags
@@ -1298,7 +1293,7 @@ class Post < ApplicationRecord
   end
 
   def levelblocked?(user = CurrentUser.user)
-    !user.is_gold? && Danbooru.config.restricted_tags.any? { |tag| tag.in?(tag_array) }
+    !user.is_gold? && RESTRICTED_TAGS.any? { |tag| tag.in?(tag_array) }
   end
 
   def banblocked?(user = CurrentUser.user)
@@ -1312,7 +1307,6 @@ class Post < ApplicationRecord
 
   def reload(options = nil)
     super
-    reset_tag_array_cache
     @pools = nil
     @tag_categories = nil
     @typed_tags = nil

config/danbooru_default_config.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+#
 # This file contains all the configuration settings for Danbooru.
 #
 # Don't edit this file. Instead, to configure your Danbooru instance, copy this