From 3c6be673247702144d04e62194b34a0bd2c52e4e Mon Sep 17 00:00:00 2001
From: Vitalii Zabaznov <vzabaznov@magento.com>
Date: Tue, 18 Feb 2020 15:08:29 -0600
Subject: [PATCH] MC-21504: Decrease Redis CPU consumptions by loading cache
 that frequently used in one pipeline P1

---
 .../Magento/Framework/Cache/Backend/Redis.php | 52 ++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/lib/internal/Magento/Framework/Cache/Backend/Redis.php b/lib/internal/Magento/Framework/Cache/Backend/Redis.php
index a2ce7001fa4a6..d2c7e9ecd9da8 100644
--- a/lib/internal/Magento/Framework/Cache/Backend/Redis.php
+++ b/lib/internal/Magento/Framework/Cache/Backend/Redis.php
@@ -7,10 +7,60 @@
 namespace Magento\Framework\Cache\Backend;
 
 /**
- * Redis wrapper to suppress exceptions on save
+ * Redis wrapper to extend current implementation behaviour.
  */
 class Redis extends \Cm_Cache_Backend_Redis
 {
+    /**
+     * Local state of preloaded keys.
+     *
+     * @var array
+     */
+    private $preloadedData = [];
+
+    /**
+     * Array of keys to be preloaded.
+     *
+     * @var array
+     */
+    private $preloadKeys = [];
+
+    /**
+     * @param array $options
+     */
+    public function __construct($options = array())
+    {
+        $this->preloadKeys = $options['preload_keys'] ?? [];
+        parent::__construct($options);
+    }
+
+    /**
+     * Load value with given id from cache
+     *
+     * @param  string  $id                     Cache id
+     * @param  boolean $doNotTestCacheValidity If set to true, the cache validity won't be tested
+     * @return bool|string
+     */
+    public function load($id, $doNotTestCacheValidity = false)
+    {
+        if (!empty($this->preloadKeys) && empty($this->preloadedData)) {
+            $redis =  $this->_slave ?? $this->_redis;
+            $redis = $redis->pipeline();
+
+            foreach ($this->preloadKeys as $key) {
+                $redis->hGet(self::PREFIX_KEY . $key, self::FIELD_DATA);
+            }
+
+            $this->preloadedData= array_combine($this->preloadKeys, $redis->exec());
+        }
+
+        if (isset($this->preloadedData[$id])) {
+            return $this->_decodeData($this->preloadedData[$id]);
+        }
+
+        return parent::load($id, $doNotTestCacheValidity = false);
+    }
+
     /**
      * The idea is that base implementation doesn't handle errors on save operations.
      * Which may occurs when Redis cannot evict keys, which is expected in some cases.