Add getAge() method to Cache class

system/classes/Cache.php

@@ -136,4 +136,15 @@ public static function exists($key)
     {
         return self::$isEnabled ? self::$instance->exists($key) : false;
     }
+
+    /**
+     * Return the timestamp of cached item
+     *
+     * @param  string $key
+     * @return int|false    the timestamp when the item exists, false otherwise
+     */
+    public static function getAge($key)
+    {
+        return self::$isEnabled ? self::$instance->getAge($key) : false;
+    }
 }

system/classes/Cache/APCu.php

@@ -3,16 +3,19 @@
 namespace Geeklog\Cache;
 
 use Geeklog\CacheInterface;
+use RuntimeException;
 
 class APCu implements CacheInterface
 {
     /**
      * APCu constructor.
+     *
+     * @throws RuntimeException
      */
     public function __construct()
     {
         if (!is_callable('apcu_store')) {
-            throw new \RuntimeException('APCu extension is not loaded');
+            throw new RuntimeException('APCu extension is not loaded');
         }
     }
 
@@ -89,4 +92,15 @@ public function exists($key)
     {
         return apcu_exists($key);
     }
+
+    /**
+     * Return the timestamp of cached item
+     *
+     * @param  string $key
+     * @return int|false    the timestamp when the item exists, false otherwise
+     */
+    public function getAge($key)
+    {
+        return $this->exists($key) ? time() : false;
+    }
 }

system/classes/Cache/FileSystem.php

@@ -209,4 +209,18 @@ public function exists($key)
 
         return @is_file($fileName) && @is_readable($fileName);
     }
+
+    /**
+     * Return the timestamp of cached item
+     *
+     * @param  string $key
+     * @return int|false    the timestamp when the item exists, false otherwise
+     */
+    public function getAge($key)
+    {
+        $fileName = $this->getFileName($key);
+        clearstatcache();
+
+        return @is_file($fileName) && @is_readable($fileName) ? filemtime($fileName) : false;
+    }
 }

system/classes/CacheInterface.php

@@ -58,4 +58,12 @@ public function delete($key);
      * @return bool
      */
     public function exists($key);
+
+    /**
+     * Return the timestamp of cached item
+     *
+     * @param  string $key
+     * @return int|false    the timestamp when the item exists, false otherwise
+     */
+    public function getAge($key);
 }