Remove the static dependency on OC_Util from Memcache

lib/private/memcache/cache.php

@@ -18,7 +18,7 @@ abstract class Cache implements \ArrayAccess {
 	 * @param string $prefix
 	 */
 	public function __construct($prefix = '') {
-		$this->prefix = \OC_Util::getInstanceId() . '/' . $prefix;
+		$this->prefix = $prefix;
 	}
 
 	public function getPrefix() {

lib/private/memcache/factory.php

@@ -9,6 +9,18 @@
 namespace OC\Memcache;
 
 class Factory {
+	/**
+	 * @var string $globalPrefix
+	 */
+	private $globalPrefix;
+
+	/**
+	 * @param string $globalPrefix
+	 */
+	public function __construct($globalPrefix) {
+		$this->globalPrefix = $globalPrefix;
+	}
+
 	/**
 	 * get a cache instance, will return null if no backend is available
 	 *
@@ -16,6 +28,7 @@ class Factory {
 	 * @return \OC\Memcache\Cache
 	 */
 	function create($prefix = '') {
+		$prefix = $this->globalPrefix . '/' . $prefix;
 		if (XCache::isAvailable()) {
 			return new XCache($prefix);
 		} elseif (APCu::isAvailable()) {

lib/private/server.php

@@ -137,7 +137,8 @@ class Server extends SimpleContainer implements IServerContainer {
 			return new UserCache();
 		});
 		$this->registerService('MemCache', function ($c) {
-			$factory = new \OC\Memcache\Factory();
+			$instanceId = \OC_Util::getInstanceId();
+			$factory = new \OC\Memcache\Factory($instanceId);
 			return $factory->create();
 		});
 		$this->registerService('ActivityManager', function($c) {

lib/public/iservercontainer.php

@@ -141,6 +141,13 @@ interface IServerContainer {
 	 */
 	function getCache();
 
+	/**
+	 * Returns an ICache instance
+	 *
+	 * @return \OCP\ICache
+	 */
+	function getMemCache();
+
 	/**
 	 * Returns the current session
 	 *