Add (back) rails-level JSON caching (mastodon#11333)

Author: Gargron

app/controllers/accounts_controller.rb

@@ -41,7 +41,7 @@ def show
 
       format.json do
         expires_in 3.minutes, public: !(authorized_fetch_mode? && signed_request_account.present?)
-        render json: @account, content_type: 'application/activity+json', serializer: ActivityPub::ActorSerializer, adapter: ActivityPub::Adapter, fields: restrict_fields_to
+        render_with_cache json: @account, content_type: 'application/activity+json', serializer: ActivityPub::ActorSerializer, adapter: ActivityPub::Adapter, fields: restrict_fields_to
       end
     end
   end

app/controllers/activitypub/collections_controller.rb

@@ -11,7 +11,7 @@ class ActivityPub::CollectionsController < ActivityPub::BaseController
 
   def show
     expires_in 3.minutes, public: public_fetch_mode?
-    render json: collection_presenter, content_type: 'application/activity+json', serializer: ActivityPub::CollectionSerializer, adapter: ActivityPub::Adapter, skip_activities: true
+    render_with_cache json: collection_presenter, content_type: 'application/activity+json', serializer: ActivityPub::CollectionSerializer, adapter: ActivityPub::Adapter, skip_activities: true
   end
 
   private

app/controllers/api/v1/custom_emojis_controller.rb

@@ -6,8 +6,7 @@ class Api::V1::CustomEmojisController < Api::BaseController
   skip_before_action :set_cache_headers
 
   def index
-    render_cached_json('api:v1:custom_emojis', expires_in: 1.minute) do
-      ActiveModelSerializers::SerializableResource.new(CustomEmoji.local.where(disabled: false).includes(:category), each_serializer: REST::CustomEmojiSerializer)
-    end
+    expires_in 3.minutes, public: true
+    render_with_cache(each_serializer: REST::CustomEmojiSerializer) { CustomEmoji.local.where(disabled: false).includes(:category) }
   end
 end

app/controllers/api/v1/instances/activity_controller.rb

@@ -7,7 +7,8 @@ class Api::V1::Instances::ActivityController < Api::BaseController
   respond_to :json
 
   def show
-    render_cached_json('api:v1:instances:activity:show', expires_in: 1.day) { activity }
+    expires_in 1.day, public: true
+    render_with_cache json: :activity, expires_in: 1.day
   end
 
   private

app/controllers/api/v1/instances/peers_controller.rb

@@ -7,7 +7,8 @@ class Api::V1::Instances::PeersController < Api::BaseController
   respond_to :json
 
   def index
-    render_cached_json('api:v1:instances:peers:index', expires_in: 1.day) { Account.remote.domains }
+    expires_in 1.day, public: true
+    render_with_cache(expires_in: 1.day) { Account.remote.domains }
   end
 
   private

app/controllers/api/v1/instances_controller.rb

@@ -5,8 +5,7 @@ class Api::V1::InstancesController < Api::BaseController
   skip_before_action :set_cache_headers
 
   def show
-    render_cached_json('api:v1:instances', expires_in: 5.minutes) do
-      ActiveModelSerializers::SerializableResource.new({}, serializer: REST::InstanceSerializer)
-    end
+    expires_in 3.minutes, public: true
+    render_with_cache json: {}, serializer: REST::InstanceSerializer
   end
 end

app/controllers/application_controller.rb

@@ -10,6 +10,7 @@ class ApplicationController < ActionController::Base
   include Localized
   include UserTrackingConcern
   include SessionTrackingConcern
+  include CacheConcern
 
   helper_method :current_account
   helper_method :current_session
@@ -115,47 +116,10 @@ def current_theme
     current_user.setting_theme
   end
 
-  def cache_collection(raw, klass)
-    return raw unless klass.respond_to?(:with_includes)
-
-    raw                    = raw.cache_ids.to_a if raw.is_a?(ActiveRecord::Relation)
-    cached_keys_with_value = Rails.cache.read_multi(*raw).transform_keys(&:id)
-    uncached_ids           = raw.map(&:id) - cached_keys_with_value.keys
-
-    klass.reload_stale_associations!(cached_keys_with_value.values) if klass.respond_to?(:reload_stale_associations!)
-
-    unless uncached_ids.empty?
-      uncached = klass.where(id: uncached_ids).with_includes.each_with_object({}) { |item, h| h[item.id] = item }
-
-      uncached.each_value do |item|
-        Rails.cache.write(item, item)
-      end
-    end
-
-    raw.map { |item| cached_keys_with_value[item.id] || uncached[item.id] }.compact
-  end
-
   def respond_with_error(code)
     respond_to do |format|
       format.any  { head code }
       format.html { render "errors/#{code}", layout: 'error', status: code }
     end
   end
-
-  def render_cached_json(cache_key, **options)
-    options[:expires_in] ||= 3.minutes
-    cache_public           = options.key?(:public) ? options.delete(:public) : true
-    content_type           = options.delete(:content_type) || 'application/json'
-
-    data = Rails.cache.fetch(cache_key, { raw: true }.merge(options)) do
-      yield.to_json
-    end
-
-    expires_in options[:expires_in], public: cache_public
-    render json: data, content_type: content_type
-  end
-
-  def set_cache_headers
-    response.headers['Vary'] = public_fetch_mode? ? 'Accept' : 'Accept, Signature'
-  end
 end

app/controllers/concerns/cache_concern.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+module CacheConcern
+  extend ActiveSupport::Concern
+
+  def render_with_cache(**options)
+    raise ArgumentError, 'only JSON render calls are supported' unless options.key?(:json) || block_given?
+
+    key        = options.delete(:key) || [[params[:controller], params[:action]].join('/'), options[:json].respond_to?(:cache_key) ? options[:json].cache_key : nil, options[:fields].nil? ? nil : options[:fields].join(',')].compact.join(':')
+    expires_in = options.delete(:expires_in) || 3.minutes
+    body       = Rails.cache.read(key, raw: true)
+
+    if body
+      render(options.except(:json, :serializer, :each_serializer, :adapter, :fields).merge(json: body))
+    else
+      if block_given?
+        options[:json] = yield
+      elsif options[:json].is_a?(Symbol)
+        options[:json] = send(options[:json])
+      end
+
+      render(options)
+      Rails.cache.write(key, response.body, expires_in: expires_in, raw: true)
+    end
+  end
+
+  def set_cache_headers
+    response.headers['Vary'] = public_fetch_mode? ? 'Accept' : 'Accept, Signature'
+  end
+
+  def cache_collection(raw, klass)
+    return raw unless klass.respond_to?(:with_includes)
+
+    raw                    = raw.cache_ids.to_a if raw.is_a?(ActiveRecord::Relation)
+    cached_keys_with_value = Rails.cache.read_multi(*raw).transform_keys(&:id)
+    uncached_ids           = raw.map(&:id) - cached_keys_with_value.keys
+
+    klass.reload_stale_associations!(cached_keys_with_value.values) if klass.respond_to?(:reload_stale_associations!)
+
+    unless uncached_ids.empty?
+      uncached = klass.where(id: uncached_ids).with_includes.each_with_object({}) { |item, h| h[item.id] = item }
+
+      uncached.each_value do |item|
+        Rails.cache.write(item, item)
+      end
+    end
+
+    raw.map { |item| cached_keys_with_value[item.id] || uncached[item.id] }.compact
+  end
+end

app/controllers/emojis_controller.rb

@@ -8,7 +8,7 @@ def show
     respond_to do |format|
       format.json do
         expires_in 3.minutes, public: true
-        render json: @emoji, content_type: 'application/activity+json', serializer: ActivityPub::EmojiSerializer, adapter: ActivityPub::Adapter
+        render_with_cache json: @emoji, content_type: 'application/activity+json', serializer: ActivityPub::EmojiSerializer, adapter: ActivityPub::Adapter
       end
     end
   end

app/controllers/statuses_controller.rb

@@ -32,14 +32,14 @@ def show
 
       format.json do
         expires_in 3.minutes, public: @status.distributable? && public_fetch_mode?
-        render json: @status, content_type: 'application/activity+json', serializer: ActivityPub::NoteSerializer, adapter: ActivityPub::Adapter
+        render_with_cache json: @status, content_type: 'application/activity+json', serializer: ActivityPub::NoteSerializer, adapter: ActivityPub::Adapter
       end
     end
   end
 
   def activity
     expires_in 3.minutes, public: @status.distributable? && public_fetch_mode?
-    render json: @status, content_type: 'application/activity+json', serializer: ActivityPub::ActivitySerializer, adapter: ActivityPub::Adapter
+    render_with_cache json: @status, content_type: 'application/activity+json', serializer: ActivityPub::ActivitySerializer, adapter: ActivityPub::Adapter
   end
 
   def embed