Rendering Performance Improvements

.rubocop.yml

@@ -20,7 +20,7 @@ Lint/MissingSuper:
   Enabled: false
 
 Metrics/MethodLength:
-  Max: 15
+  Max: 20
 
 Metrics/AbcSize:
   Enabled: false

lib/blueprinter/base.rb

@@ -45,7 +45,7 @@ class << self
       #   end
       #
       # @return [Field] A Field object
-      def identifier(method, name: method, extractor: Blueprinter.configuration.extractor_default.new, &block)
+      def identifier(method, name: method, extractor: Blueprinter.configuration.default_extractor, &block)
         view_collection[:identifier] << Field.new(
           method,
           name,
@@ -116,7 +116,7 @@ def field(method, options = {}, &block)
         current_view << Field.new(
           method,
           options.fetch(:name) { method },
-          options.fetch(:extractor) { Blueprinter.configuration.extractor_default.new },
+          options.fetch(:extractor) { Blueprinter.configuration.default_extractor },
           self,
           options.merge(block:)
         )
@@ -159,7 +159,7 @@ def association(method, options = {}, &block)
         current_view << Association.new(
           method:,
           name: options.fetch(:name) { method },
-          extractor: options.fetch(:extractor) { AssociationExtractor.new },
+          extractor: options.fetch(:extractor) { association_extractor },
           blueprint: options.fetch(:blueprint),
           parent_blueprint: self,
           view: options.fetch(:view, :default),
@@ -369,6 +369,10 @@ def current_view
       def inherited(subclass)
         subclass.send(:view_collection).inherit(view_collection)
       end
+
+      def association_extractor
+        @_association_extractor ||= AssociationExtractor.new
+      end
     end
   end
 end

lib/blueprinter/configuration.rb

@@ -12,15 +12,14 @@ class Configuration
       :datetime_format,
       :default_transformers,
       :deprecations,
-      :extractor_default,
       :field_default,
       :generator,
       :if,
       :method,
       :sort_fields_by,
       :unless
     )
-    attr_reader :extensions
+    attr_reader :extensions, :extractor_default
 
     VALID_CALLABLES = %i[if unless].freeze
 
@@ -59,5 +58,21 @@ def jsonify(blob)
     def valid_callable?(callable_name)
       VALID_CALLABLES.include?(callable_name)
     end
+
+    # @param extractor [Class<Blueprinter::AutoExtractor>]
+    def extractor_default=(extractor)
+      reset_default_extractor!
+
+      @extractor_default = extractor
+    end
+
+    # @return [Blueprinter::AutoExtractor]
+    def default_extractor
+      @_default_extractor ||= extractor_default.new
+    end
+
+    def reset_default_extractor!
+      @_default_extractor = nil
+    end
   end
 end

lib/blueprinter/extractors/association_extractor.rb

@@ -9,11 +9,16 @@ class AssociationExtractor < Extractor
     include EmptyTypes
 
     def initialize
-      @extractor = Blueprinter.configuration.extractor_default.new
+      @extractor = Blueprinter.configuration.default_extractor
     end
 
     def extract(association_name, object, local_options, options = {})
-      options_without_default = options.except(:default, :default_if)
+      options_without_default = if options.key?(:default) || options.key?(:default_if)
+                                  options.except(:default, :default_if)
+                                else
+                                  options
+                                end
+
       # Merge in assocation options hash
       local_options = local_options.merge(options[:options]) if options[:options].is_a?(Hash)
       value = @extractor.extract(association_name, object, local_options, options_without_default)

lib/blueprinter/formatters/date_time_formatter.rb

@@ -2,7 +2,7 @@
 
 module Blueprinter
   class DateTimeFormatter
-    InvalidDateTimeFormatterError = Class.new(BlueprinterError)
+    class InvalidDateTimeFormatterError < BlueprinterError; end
 
     def format(value, options)
       return value if value.nil?

lib/blueprinter/rendering.rb

@@ -30,7 +30,7 @@ module Rendering
     #
     # @return [String] JSON formatted String
     def render(object, options = {})
-      jsonify(build_result(object: object, options: options))
+      jsonify(build_result(object:, options:))
     end
 
     # Generates a Hash representation of the provided object.
@@ -55,7 +55,7 @@ def render(object, options = {})
     #
     # @return [Hash]
     def render_as_hash(object, options = {})
-      build_result(object: object, options: options)
+      build_result(object:, options:)
     end
 
     # Generates a JSONified hash.
@@ -80,7 +80,7 @@ def render_as_hash(object, options = {})
     #
     # @return [Hash]
     def render_as_json(object, options = {})
-      build_result(object: object, options: options).as_json
+      build_result(object:, options:).as_json
     end
 
     # Converts an object into a Hash representation based on provided view.
@@ -122,35 +122,43 @@ def prepare(object, view_name:, local_options:)
     attr_reader :blueprint, :options
 
     def prepare_data(object, view_name, local_options)
+      # Since we're currently providing the current view in the local_options hash when we extract fields, we can merge
+      # it in ahead of time to avoid allocating a new hash for every field extraction.
+      local_options_with_view = local_options.merge(view: view_name)
+
       if array_like?(object)
         object.map do |obj|
           object_to_hash(
             obj,
-            view_name: view_name,
-            local_options: local_options
+            view_name:,
+            local_options: local_options_with_view
           )
         end
       else
         object_to_hash(
           object,
-          view_name: view_name,
-          local_options: local_options
+          view_name:,
+          local_options: local_options_with_view
         )
       end
     end
 
     def object_to_hash(object, view_name:, local_options:)
-      result_hash = view_collection.fields_for(view_name).each_with_object({}) do |field, hash|
+      result_hash = {}
+
+      view_collection.fields_for(view_name).each do |field|
         next if field.skip?(field.name, object, local_options)
 
-        value = field.extract(object, local_options.merge(view: view_name))
+        value = field.extract(object, local_options)
         next if value.nil? && field.options[:exclude_if_nil]
 
-        hash[field.name] = value
+        result_hash[field.name] = value
       end
+
       view_collection.transformers(view_name).each do |transformer|
         transformer.transform(result_hash, object, local_options)
       end
+
       result_hash
     end
 
@@ -173,11 +181,11 @@ def add_metadata(object:, metadata:, root:)
     end
 
     def build_result(object:, options:)
-      view_name = options.fetch(:view, :default) || :default
+      view_name = options[:view] || :default
 
       prepared_object = hashify(
         object,
-        view_name: view_name,
+        view_name:,
         local_options: options.except(:view, :root, :meta)
       )
       object_with_root = apply_root_key(

lib/blueprinter/view_collection.rb

@@ -4,6 +4,16 @@
 
 module Blueprinter
   # @api private
+  #
+  # ViewCollection manages the views defined in a Blueprint, along with their fields and transformers.
+  #
+  # To improve performance, the "structure" of each view is cached. Once the first view is accessed, we prewarm the
+  # cache for _all_ views (while this isn't the _most_ optimal approach, the overhead is negligible, and allows the
+  # caching logic to be quite simple).
+  #
+  # To ensure thread safety, we build out the cache within a double-checked mutex.
+  #
+  # rubocop:disable Metrics/ClassLength
   class ViewCollection
     attr_reader :views, :sort_by_definition
 
@@ -13,45 +23,100 @@ def initialize
         default: View.new(:default)
       }
       @sort_by_definition = Blueprinter.configuration.sort_fields_by.eql?(:definition)
+      @cache_mutex = Mutex.new
+      @finalized = false
     end
 
     def inherit(view_collection)
       view_collection.views.each do |view_name, view|
         self[view_name].inherit(view)
       end
+
+      # Reset finalization just in case since the structure of the views has changed.
+      @finalized = false
     end
 
+    # @param [String] view_name
+    # @return [Boolean] true if the view exists, false otherwise
     def view?(view_name)
       views.key? view_name
     end
 
+    # Returns an array of Field objects for the provided View.
+    # @param [String] view_name
+    # @return [Array<Field>]
     def fields_for(view_name)
-      return identifier_fields if view_name == :identifier
+      ensure_finalized!
 
-      fields, excluded_fields = sortable_fields(view_name)
-      sorted_fields = sort_by_definition ? sort_by_def(view_name, fields) : fields.values.sort_by(&:name)
-
-      (identifier_fields + sorted_fields).tap do |fields_array|
-        fields_array.reject! { |field| excluded_fields.include?(field.name) }
-      end
+      @cached_fields_for[view_name]
     end
 
+    # Returns an array of Transformer objects for the provided View.
+    # @param [String] view_name
+    # @return [Array<Transformer>]
     def transformers(view_name)
-      included_transformers = gather_transformers_from_included_views(view_name).reverse
-      all_transformers = [*views[:default].view_transformers, *included_transformers].uniq
-      all_transformers.empty? ? Blueprinter.configuration.default_transformers : all_transformers
+      ensure_finalized!
+
+      @cached_transformers[view_name]
     end
 
+    # @param [String] view_name
+    # @return [View]
     def [](view_name)
-      @views[view_name] ||= View.new(view_name)
+      return @views[view_name] if @views.key?(view_name)
+
+      @cache_mutex.synchronize do
+        unless @views.key?(view_name)
+          @views[view_name] = View.new(view_name)
+          @finalized = false
+        end
+        @views[view_name]
+      end
     end
 
     private
 
+    attr_reader :cache_mutex
+
     def identifier_fields
       views[:identifier].fields.values
     end
 
+    def ensure_finalized!
+      return if @finalized
+
+      @cache_mutex.synchronize do
+        return if @finalized
+
+        @cached_fields_for = {}
+        @cached_transformers = {}
+
+        views.each_key do |view_name|
+          @cached_fields_for[view_name] = build_fields_for(view_name).freeze
+          @cached_transformers[view_name] = build_transformers(view_name).freeze
+        end
+
+        @finalized = true
+      end
+    end
+
+    def build_fields_for(view_name)
+      return identifier_fields if view_name == :identifier
+
+      fields, excluded_fields = sortable_fields(view_name)
+      sorted_fields = sort_by_definition ? sort_by_def(view_name, fields) : fields.values.sort_by(&:name)
+
+      (identifier_fields + sorted_fields).tap do |fields_array|
+        fields_array.reject! { |field| excluded_fields.include?(field.name) }
+      end
+    end
+
+    def build_transformers(view_name)
+      included_transformers = gather_transformers_from_included_views(view_name).reverse
+      all_transformers = [*views[:default].view_transformers, *included_transformers].uniq
+      all_transformers.empty? ? Blueprinter.configuration.default_transformers : all_transformers
+    end
+
     # @param [String] view_name
     # @return [Array<(Hash, Hash<String, NilClass>)>] fields, excluded_fields
     def sortable_fields(view_name)
@@ -104,4 +169,5 @@ def gather_transformers_from_included_views(view_name)
       [*already_included_transformers, *current_view.view_transformers].uniq
     end
   end
+  # rubocop:enable Metrics/ClassLength
 end

spec/units/configuration_spec.rb

@@ -3,7 +3,7 @@
 require 'oj'
 require 'yajl'
 
-describe 'Blueprinter' do
+describe 'Blueprinter::Configuration' do
   describe '#configure' do
     before { Blueprinter.configure { |config| config.generator = JSON } }
     after { reset_blueprinter_config! }
@@ -88,19 +88,26 @@ class UpcaseTransform < Blueprinter::Transformer; end
     end
   end
 
-  describe "::Configuration" do
-    describe '#valid_callable?' do
-      it 'should return true for valid callables' do
-        [:if, :unless].each do |option|
-          actual = Blueprinter.configuration.valid_callable?(option)
-          expect(actual).to be(true)
-        end
-      end
+  describe '#default_extractor' do
+    it 'returns an instance of the default extractor' do
+      expect(Blueprinter.configuration.default_extractor).to be_an_instance_of(Blueprinter::AutoExtractor)
+    end
 
-      it 'should return false for invalid callable' do
-        actual = Blueprinter.configuration.valid_callable?(:invalid_option)
-        expect(actual).to be(false)
+    it 'does not create a new instance on subsequent calls' do
+      expect(Blueprinter.configuration.default_extractor).to eq(Blueprinter.configuration.default_extractor)
+    end
+  end
+  describe '#valid_callable?' do
+    it 'should return true for valid callables' do
+      [:if, :unless].each do |option|
+        actual = Blueprinter.configuration.valid_callable?(option)
+        expect(actual).to be(true)
       end
     end
+
+    it 'should return false for invalid callable' do
+      actual = Blueprinter.configuration.valid_callable?(:invalid_option)
+      expect(actual).to be(false)
+    end
   end
 end