MAGETWO-66343: [Performance] Anomaly increase in redis traffic

Author: Yaroslav Onischenko

app/code/Magento/Config/App/Config/Type/System.php

@@ -24,7 +24,7 @@ class System implements ConfigTypeInterface
     private $source;
 
     /**
-     * @var DataObject[]
+     * @var DataObject
      */
     private $data;
 
@@ -129,6 +129,10 @@ public function get($path = '')
 
     /**
      * Check whether configuration is cached
+     *
+     * In case configuration cache exists method 'load' returns
+     * value equal to $this->cacheExistenceKey
+     *
      * @return bool
      */
     private function isCacheExists()
@@ -139,6 +143,9 @@ private function isCacheExists()
     /**
      * Explode path by '/'(forward slash) separator
      *
+     * In case $path string contains forward slash symbol(/) the $path is exploded and parts array is returned
+     * In other case empty array is returned
+     *
      * @param string $path
      * @return array
      */
@@ -154,6 +161,11 @@ private function getPathParts($path)
     /**
      * Check whether requested configuration data is read to memory
      *
+     * Because of configuration is cached partially each part can be loaded separately
+     * Method performs check if corresponding system configuration part is already loaded to memory
+     * and value can be retrieved directly without cache look up
+     *
+     *
      * @param string $path
      * @return bool
      */
@@ -166,6 +178,9 @@ private function isConfigRead($path)
     /**
      * Load configuration from all the sources
      *
+     * System configuration is loaded in 3 steps performing consecutive calls to
+     * Pre Processor, Fallback Processor, Post Processor accordingly
+     *
      * @return array
      */
     private function loadConfig()
@@ -206,6 +221,10 @@ private function cacheConfig($data)
     /**
      * Read cached configuration
      *
+     * Read section of system configuration corresponding to requested $path from cache
+     * Configuration stored to internal property right after load to prevent additional
+     * requests to cache storage
+     *
      * @param string $path
      * @return mixed
      */
@@ -219,12 +238,11 @@ private function readFromCache($path)
         $pathParts = $this->getPathParts($path);
         if (!empty($pathParts)) {
             $result = $this->cache->load(self::CONFIG_TYPE . '_' . $pathParts[0] . $pathParts[1]);
-        }
-
-        if ($result !== false && $result !== null) {
-            $readData = $this->data->getData();
-            $readData[$pathParts[0]][$pathParts[1]] = $this->serializer->unserialize($result);
-            $this->data = new DataObject($readData);
+            if ($result !== false) {
+                $readData = $this->data->getData();
+                $readData[$pathParts[0]][$pathParts[1]] = $this->serializer->unserialize($result);
+                $this->data->setData($readData);
+            }
         }
 
         return $this->data->getData($path);
@@ -233,6 +251,10 @@ private function readFromCache($path)
     /**
      * Clean cache and global variables cache
      *
+     * Next items cleared:
+     * - Internal property intended to store already loaded configuration data
+     * - All records in cache storage tagged with CACHE_TAG
+     *
      * @return void
      */
     public function clean()

app/code/Magento/Config/Test/Unit/App/Config/Type/SystemTest.php

@@ -69,9 +69,8 @@ public function setUp()
         $this->preProcessor = $this->getMockBuilder(PreProcessorInterface::class)
             ->getMockForAbstractClass();
         $this->serializer = $this->getMockBuilder(SerializerInterface::class)
-            ->disableOriginalConstructor()
-            ->setMethods(['serialize', 'unserialize'])
             ->getMock();
+
         $this->configType = new System(
             $this->source,
             $this->postProcessor,

dev/tests/integration/testsuite/Magento/Catalog/_files/product_simple.php

@@ -21,7 +21,9 @@
 $tpExtensionAttributesFactory = $objectManager->get(ProductTierPriceExtensionFactory::class);
 
 $adminWebsite = $objectManager->get(\Magento\Store\Api\WebsiteRepositoryInterface::class)->get('admin');
-$tierPriceWebsiteId = $tpExtensionAttributesFactory->create()->setWebsiteId($adminWebsite->getId());
+$tierPriceExtensionAttributes1 = $tpExtensionAttributesFactory->create()
+    ->setWebsiteId($adminWebsite->getId());
+
 $tierPrices[] = $tierPriceFactory->create(
     [
         'data' => [
@@ -30,7 +32,8 @@
             'value' => 8
         ]
     ]
-)->setExtensionAttributes($tierPriceWebsiteId);
+)->setExtensionAttributes($tierPriceExtensionAttributes1);
+
 $tierPrices[] = $tierPriceFactory->create(
     [
         'data' => [
@@ -39,7 +42,8 @@
             'value' => 5
         ]
     ]
-)->setExtensionAttributes($tierPriceWebsiteId);
+)->setExtensionAttributes($tierPriceExtensionAttributes1);
+
 $tierPrices[] = $tierPriceFactory->create(
     [
         'data' => [
@@ -48,11 +52,11 @@
             'value' => 5
         ]
     ]
-)->setExtensionAttributes($tierPriceWebsiteId);
+)->setExtensionAttributes($tierPriceExtensionAttributes1);
 
-$tierPricePercentageValue = $tpExtensionAttributesFactory->create()
-    ->setPercentageValue(50)
-    ->setWebsiteId($adminWebsite->getId());
+$tierPriceExtensionAttributes2 = $tpExtensionAttributesFactory->create()
+    ->setWebsiteId($adminWebsite->getId())
+    ->setPercentageValue(50);
 
 $tierPrices[] = $tierPriceFactory->create(
     [
@@ -61,7 +65,7 @@
             'qty' => 10
         ]
     ]
-)->setExtensionAttributes($tierPricePercentageValue);
+)->setExtensionAttributes($tierPriceExtensionAttributes2);
 
 /** @var $product \Magento\Catalog\Model\Product */
 $product = $objectManager->create(\Magento\Catalog\Model\Product::class);

dev/tests/integration/testsuite/Magento/Store/_files/second_website_with_second_currency.php

@@ -28,6 +28,9 @@
     0
 );
 
+/**
+ * Configuration cache clean is required to reload currency setting
+ */
 /** @var Magento\Config\App\Config\Type\System $config */
 $config = $objectManager->get(\Magento\Config\App\Config\Type\System::class);
 $config->clean();

lib/internal/Magento/Framework/App/Config/ConfigTypeInterface.php

@@ -13,10 +13,13 @@
 interface ConfigTypeInterface
 {
     /**
-     * Retrieve configuration raw data array.
+     * Retrieve configuration data.
+     *
+     * Returns full configuration array in case $path is empty.
+     * In case $path is not empty return value can be either array or scalar
      *
      * @param string $path
-     * @return mixed
+     * @return array|int|string|boolean
      */
     public function get($path = '');