Added first version of ConfigCacheSaver

src/Core/Config/Configuration.php

@@ -10,6 +10,16 @@ namespace Friendica\Core\Config;
  */
 class Configuration
 {
+	/**
+	 * The blacklist of configuration settings, which should not get saved to the backend
+	 * @var array
+	 */
+	private $configSaveBlacklist = [
+		'config' => [
+			'hostname' => true,
+		]
+	];
+
 	/**
 	 * @var Cache\IConfigCache
 	 */
@@ -117,7 +127,7 @@ class Configuration
 		$cached = $this->configCache->set($cat, $key, $value);
 
 		// If there is no connected adapter, we're finished
-		if (!$this->configAdapter->isConnected()) {
+		if (!$this->configAdapter->isConnected() && !empty($this->configSaveBlacklist[$cat][$key])) {
 			return $cached;
 		}