add perfomance chapters

implementation/18-caching/src/Service/Cache/ApcuCache.php

@@ -0,0 +1,21 @@
+<?php declare(strict_types=1);
+
+namespace Lubian\NoFramework\Service\Cache;
+
+use function apcu_add;
+use function apcu_fetch;
+
+final class ApcuCache implements EasyCache
+{
+    public function get(string $key, callable $callback, int $ttl = 0): mixed
+    {
+        $success = false;
+        $result = apcu_fetch($key, $success);
+        if ($success === true) {
+            return $result;
+        }
+        $result = $callback();
+        apcu_add($key, $result, $ttl);
+        return $result;
+    }
+}