Add cache decorator for UserModel

app/Decorator/UserCacheDecorator.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace Kanboard\Decorator;
+
+use Kanboard\Core\Cache\CacheInterface;
+use Kanboard\Model\UserModel;
+
+/**
+ * Class UserCacheDecorator
+ *
+ * @package Kanboard\Decorator
+ * @author  Frederic Guillot
+ */
+class UserCacheDecorator
+{
+    protected $cachePrefix = 'user_model:';
+
+    /**
+     * @var CacheInterface
+     */
+    protected $cache;
+
+    /**
+     * @var UserModel
+     */
+    private $userModel;
+
+    /**
+     * UserCacheDecorator constructor.
+     *
+     * @param CacheInterface $cache
+     * @param UserModel      $userModel
+     */
+    public function __construct(CacheInterface $cache, UserModel $userModel)
+    {
+        $this->cache = $cache;
+        $this->userModel = $userModel;
+    }
+
+    /**
+     * Get a specific user by the username
+     *
+     * @access public
+     * @param  string  $username  Username
+     * @return array
+     */
+    public function getByUsername($username)
+    {
+        $key = $this->cachePrefix.$username;
+        $user = $this->cache->get($key);
+
+        if ($user === null) {
+            $user = $this->userModel->getByUsername($username);
+            $this->cache->set($key, $user);
+        }
+
+        return $user;
+    }
+}