Add caching for product attributes used in sales rules

Author: ihor-sviziev

app/code/Magento/SalesRule/Model/Plugin/QuoteConfigProductAttributes.php

@@ -3,8 +3,10 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\SalesRule\Model\Plugin;
 
+use Magento\Quote\Model\Quote\Config;
 use Magento\SalesRule\Model\ResourceModel\Rule as RuleResource;
 
 /**
@@ -15,31 +17,50 @@ class QuoteConfigProductAttributes
     /**
      * @var RuleResource
      */
-    protected $_ruleResource;
+    private $ruleResource;
+
+    /**
+     * @var array|null
+     */
+    private $activeAttributes;
 
     /**
      * @param RuleResource $ruleResource
      */
     public function __construct(RuleResource $ruleResource)
     {
-        $this->_ruleResource = $ruleResource;
+        $this->ruleResource = $ruleResource;
     }
 
     /**
      * Append sales rule product attribute keys to select by quote item collection
      *
-     * @param \Magento\Quote\Model\Quote\Config $subject
+     * @param Config $subject
      * @param array $attributeKeys
      *
      * @return array
      * @SuppressWarnings(PHPMD.UnusedFormalParameter)
      */
-    public function afterGetProductAttributes(\Magento\Quote\Model\Quote\Config $subject, array $attributeKeys)
+    public function afterGetProductAttributes(Config $subject, array $attributeKeys): array
     {
-        $attributes = $this->_ruleResource->getActiveAttributes();
+        $attributes = $this->getActiveAttributes();
+
         foreach ($attributes as $attribute) {
             $attributeKeys[] = $attribute['attribute_code'];
         }
+
         return $attributeKeys;
     }
+
+    /**
+     * @return array
+     */
+    private function getActiveAttributes(): array
+    {
+        if ($this->activeAttributes === null) {
+            $this->activeAttributes = $this->ruleResource->getActiveAttributes();
+        }
+
+        return $this->activeAttributes;
+    }
 }