Reduce allocations in #with_collection (#2333)

* Add test of number of allocations when rendering with with_collection

* Ensure one-time initializations are done before testing allocations

* Cache calculated collection parameter

* Cache collection_counter_parameter

* Cache collection_iteration_parameter

* Cache initialize_parameter_names

* Add expected number of allocations for all tested Ruby/Rails combinations

* Remove code handling obsolete Rails version

Author: mvz

lib/view_component/base.rb

@@ -660,12 +660,12 @@ def validate_initialization_parameters!
 
       # @private
       def collection_parameter
-        provided_collection_parameter || name && name.demodulize.underscore.chomp("_component").to_sym
+        @provided_collection_parameter ||= name && name.demodulize.underscore.chomp("_component").to_sym
       end
 
       # @private
       def collection_counter_parameter
-        :"#{collection_parameter}_counter"
+        @collection_counter_parameter ||= :"#{collection_parameter}_counter"
       end
 
       # @private
@@ -675,7 +675,7 @@ def counter_argument_present?
 
       # @private
       def collection_iteration_parameter
-        :"#{collection_parameter}_iteration"
+        @collection_iteration_parameter ||= :"#{collection_parameter}_iteration"
       end
 
       # @private
@@ -691,11 +691,12 @@ def splatted_keyword_argument_present?
       end
 
       def initialize_parameter_names
-        return attribute_names.map(&:to_sym) if respond_to?(:attribute_names)
-
-        return attribute_types.keys.map(&:to_sym) if Rails::VERSION::MAJOR <= 5 && respond_to?(:attribute_types)
-
-        initialize_parameters.map(&:last)
+        @initialize_parameter_names ||=
+          if respond_to?(:attribute_names)
+            attribute_names.map(&:to_sym)
+          else
+            initialize_parameters.map(&:last)
+          end
       end
 
       def initialize_parameters

test/sandbox/test/rendering_test.rb

@@ -612,6 +612,32 @@ def test_render_collection
     assert_selector("p", text: "Mints counter: 1")
   end
 
+  def test_render_collection_inline_allocations
+    # Stabilize compilation status ahead of testing allocations to simulate rendering
+    # performance with compiled component
+    ViewComponent::CompileCache.cache.delete(ProductComponent)
+    ProductComponent.ensure_compiled
+
+    allocations =
+      if Rails.version.to_f < 8.0
+        {"3.3.8" => 128, "3.2.8" => 125, "3.1.7" => 125, "3.0.7" => 122}
+      elsif Rails.version.split(".").first(2).map(&:to_i) == [8, 0]
+        {"3.5.0" => 121, "3.4.4" => 121, "3.3.8" => 128}
+      else
+        {"3.4.4" => 119}
+      end
+
+    products = [Product.new(name: "Radio clock"), Product.new(name: "Mints")]
+    notice = "On sale"
+    # Ensure any one-time allocations are done
+    render_inline(ProductComponent.with_collection(products, notice: notice))
+
+    assert_allocations(**allocations) do
+      render_inline(ProductComponent.with_collection(products, notice: notice))
+    end
+    assert_selector("h1", text: "Product", count: 2)
+  end
+
   def test_render_collection_custom_collection_parameter_name
     coupons = [Coupon.new(percent_off: 20), Coupon.new(percent_off: 50)]
     render_inline(ProductCouponComponent.with_collection(coupons))