diff --git a/src/Core/Cache.php b/src/Core/Cache.php
index 4202db325c..cc77d9bfd0 100644
--- a/src/Core/Cache.php
+++ b/src/Core/Cache.php
@@ -4,8 +4,7 @@
  */
 namespace Friendica\Core;
 
-use Friendica\Core\Cache;
-use Friendica\Core\Config;
+use Friendica\Core\Cache\CacheDriverFactory;
 
 /**
  * @brief Class for storing data for a short time
@@ -24,31 +23,13 @@ class Cache extends \Friendica\BaseObject
 	/**
 	 * @var Cache\ICacheDriver
 	 */
-	static $driver = null;
+	private static $driver = null;
 
 	public static function init()
 	{
-		switch(Config::get('system', 'cache_driver', 'database')) {
-			case 'memcache':
-				$memcache_host = Config::get('system', 'memcache_host', '127.0.0.1');
-				$memcache_port = Config::get('system', 'memcache_port', 11211);
+		$driver_name = Config::get('system', 'cache_driver', 'database');
 
-				self::$driver = new Cache\MemcacheCacheDriver($memcache_host, $memcache_port);
-				break;
-			case 'memcached':
-				$memcached_hosts = Config::get('system', 'memcached_hosts', [['127.0.0.1', 11211]]);
-
-				self::$driver = new Cache\MemcachedCacheDriver($memcached_hosts);
-				break;
-			case 'redis':
-				$redis_host = Config::get('system', 'redis_host', '127.0.0.1');
-				$redis_port = Config::get('system', 'redis_port', 6379);
-
-				self::$driver = new Cache\RedisCacheDriver($redis_host, $redis_port);
-				break;
-			default:
-				self::$driver = new Cache\DatabaseCacheDriver();
-		}
+		self::$driver = CacheDriverFactory::create($driver_name);
 	}
 
 	/**
diff --git a/src/Core/Cache/ArrayCache.php b/src/Core/Cache/ArrayCache.php
new file mode 100644
index 0000000000..71610c39df
--- /dev/null
+++ b/src/Core/Cache/ArrayCache.php
@@ -0,0 +1,83 @@
+<?php
+
+namespace Friendica\Core\Cache;
+
+
+use Friendica\Core\Cache;
+
+/**
+ * Implementation of the IMemoryCacheDriver mainly for testing purpose
+ *
+ * Class ArrayCache
+ *
+ * @package Friendica\Core\Cache
+ */
+class ArrayCache implements IMemoryCacheDriver
+{
+	use TraitCompareDelete;
+
+	/** @var array Array with the cached data */
+	protected $cachedData = array();
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function get($key)
+	{
+		if (isset($this->cachedData[$key])) {
+			return $this->cachedData[$key];
+		}
+		return null;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function set($key, $value, $ttl = Cache::FIVE_MINUTES)
+	{
+		$this->cachedData[$key] = $value;
+		return true;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function delete($key)
+	{
+		unset($this->cachedData[$key]);
+		return true;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function clear()
+	{
+		$this->cachedData = [];
+		return true;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function add($key, $value, $ttl = Cache::FIVE_MINUTES)
+	{
+		if (isset($this->cachedData[$key])) {
+			return false;
+		} else {
+			return $this->set($key, $value, $ttl);
+		}
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function compareSet($key, $oldValue, $newValue, $ttl = Cache::FIVE_MINUTES)
+	{
+		if ($this->get($key) === $oldValue) {
+			return $this->set($key, $newValue);
+		} else {
+			return false;
+		}
+	}
+}
diff --git a/src/Core/Cache/CacheDriverFactory.php b/src/Core/Cache/CacheDriverFactory.php
new file mode 100644
index 0000000000..8fbdc1549e
--- /dev/null
+++ b/src/Core/Cache/CacheDriverFactory.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Friendica\Core\Cache;
+
+use Friendica\Core\Config;
+
+/**
+ * Class CacheDriverFactory
+ *
+ * @package Friendica\Core\Cache
+ *
+ * A basic class to generate a CacheDriver
+ */
+class CacheDriverFactory
+{
+	/**
+	 * This method creates a CacheDriver for the given cache driver name
+	 *
+	 * @param string $driver The name of the cache driver
+	 * @return ICacheDriver  The instance of the CacheDriver
+	 * @throws \Exception    The exception if something went wrong during the CacheDriver creation
+	 */
+	public static function create($driver) {
+
+		switch ($driver) {
+			case 'memcache':
+				$memcache_host = Config::get('system', 'memcache_host', '127.0.0.1');
+				$memcache_port = Config::get('system', 'memcache_port', 11211);
+
+				return new MemcacheCacheDriver($memcache_host, $memcache_port);
+				break;
+
+			case 'memcached':
+				$memcached_hosts = Config::get('system', 'memcached_hosts', [['127.0.0.1', 11211]]);
+
+				return new MemcachedCacheDriver($memcached_hosts);
+				break;
+			case 'redis':
+				$redis_host = Config::get('system', 'redis_host', '127.0.0.1');
+				$redis_port = Config::get('system', 'redis_port', 6379);
+
+				return new RedisCacheDriver($redis_host, $redis_port);
+				break;
+			default:
+				return new DatabaseCacheDriver();
+		}
+	}
+}
diff --git a/src/Core/Cache/DatabaseCacheDriver.php b/src/Core/Cache/DatabaseCacheDriver.php
index 7248e0b349..0838a66c7a 100644
--- a/src/Core/Cache/DatabaseCacheDriver.php
+++ b/src/Core/Cache/DatabaseCacheDriver.php
@@ -33,11 +33,11 @@ class DatabaseCacheDriver implements ICacheDriver
 		return null;
 	}
 
-	public function set($key, $value, $duration = Cache::MONTH)
+	public function set($key, $value, $ttl = Cache::FIVE_MINUTES)
 	{
 		$fields = [
 			'v'       => serialize($value),
-			'expires' => DateTimeFormat::utc('now + ' . $duration . ' seconds'),
+			'expires' => DateTimeFormat::utc('now + ' . $ttl . ' seconds'),
 			'updated' => DateTimeFormat::utcNow()
 		];
 
diff --git a/src/Core/Cache/ICacheDriver.php b/src/Core/Cache/ICacheDriver.php
index be896edf7f..ced7b4e216 100644
--- a/src/Core/Cache/ICacheDriver.php
+++ b/src/Core/Cache/ICacheDriver.php
@@ -25,17 +25,16 @@ interface ICacheDriver
 	 *
 	 * @param string  $key      The cache key
 	 * @param mixed   $value    The value to store
-	 * @param integer $duration The cache lifespan, must be one of the Cache constants
+	 * @param integer $ttl The cache lifespan, must be one of the Cache constants
 	 *
 	 * @return bool
 	 */
-	public function set($key, $value, $duration = Cache::MONTH);
-
+	public function set($key, $value, $ttl = Cache::FIVE_MINUTES);
 
 	/**
 	 * Delete a key from the cache
 	 *
-	 * @param string $key
+	 * @param string $key      The cache key
 	 *
 	 * @return bool
 	 */
diff --git a/src/Core/Cache/IMemoryCacheDriver.php b/src/Core/Cache/IMemoryCacheDriver.php
new file mode 100644
index 0000000000..a50e2d1d48
--- /dev/null
+++ b/src/Core/Cache/IMemoryCacheDriver.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace Friendica\Core\Cache;
+use Friendica\Core\Cache;
+
+/**
+ * This interface defines methods for Memory-Caches only
+ *
+ * Interface IMemoryCacheDriver
+ *
+ * @package Friendica\Core\Cache
+ */
+interface IMemoryCacheDriver extends ICacheDriver
+{
+	/**
+	 * Sets a value if it's not already stored
+	 *
+	 * @param string $key      The cache key
+	 * @param mixed  $value    The old value we know from the cache
+	 * @param int    $ttl      The cache lifespan, must be one of the Cache constants
+	 * @return bool
+	 */
+	public function add($key, $value, $ttl = Cache::FIVE_MINUTES);
+
+	/**
+	 * Compares if the old value is set and sets the new value
+	 *
+	 * @param string $key         The cache key
+	 * @param mixed  $oldValue    The old value we know from the cache
+	 * @param mixed  $newValue    The new value we want to set
+	 * @param int    $ttl      	   The cache lifespan, must be one of the Cache constants
+	 *
+	 * @return bool
+	 */
+	public function compareSet($key, $oldValue, $newValue, $ttl = Cache::FIVE_MINUTES);
+
+	/**
+	 * Compares if the old value is set and removes it
+	 *
+	 * @param string $key          The cache key
+	 * @param mixed  $value        The old value we know and want to delete
+	 * @return bool
+	 */
+	public function compareDelete($key, $value);
+}
diff --git a/src/Core/Cache/MemcacheCacheDriver.php b/src/Core/Cache/MemcacheCacheDriver.php
index 1537be25b2..8eb45d907e 100644
--- a/src/Core/Cache/MemcacheCacheDriver.php
+++ b/src/Core/Cache/MemcacheCacheDriver.php
@@ -10,10 +10,13 @@ use Friendica\Core\Cache;
  *
  * @author Hypolite Petovan <mrpetovan@gmail.com>
  */
-class MemcacheCacheDriver extends BaseObject implements ICacheDriver
+class MemcacheCacheDriver extends BaseObject implements IMemoryCacheDriver
 {
+	use TraitCompareSet;
+	use TraitCompareDelete;
+
 	/**
-	 * @var Memcache
+	 * @var \Memcache
 	 */
 	private $memcache;
 
@@ -30,6 +33,9 @@ class MemcacheCacheDriver extends BaseObject implements ICacheDriver
 		}
 	}
 
+	/**
+	 * (@inheritdoc)
+	 */
 	public function get($key)
 	{
 		$return = null;
@@ -54,24 +60,49 @@ class MemcacheCacheDriver extends BaseObject implements ICacheDriver
 		return $return;
 	}
 
-	public function set($key, $value, $duration = Cache::MONTH)
+	/**
+	 * (@inheritdoc)
+	 */
+	public function set($key, $value, $ttl = Cache::FIVE_MINUTES)
 	{
 		// We store with the hostname as key to avoid problems with other applications
-		return $this->memcache->set(
-			self::getApp()->get_hostname() . ":" . $key,
-			serialize($value),
-			MEMCACHE_COMPRESSED,
-			time() + $duration
-		);
+		if ($ttl > 0) {
+			return $this->memcache->set(
+				self::getApp()->get_hostname() . ":" . $key,
+				serialize($value),
+				MEMCACHE_COMPRESSED,
+				time() + $ttl
+			);
+		} else {
+			return $this->memcache->set(
+				self::getApp()->get_hostname() . ":" . $key,
+				serialize($value),
+				MEMCACHE_COMPRESSED
+			);
+		}
 	}
 
+	/**
+	 * (@inheritdoc)
+	 */
 	public function delete($key)
 	{
 		return $this->memcache->delete($key);
 	}
 
+	/**
+	 * (@inheritdoc)
+	 */
 	public function clear()
 	{
-		return true;
+		return $this->memcache->flush();
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function add($key, $value, $ttl = Cache::FIVE_MINUTES)
+	{
+		return $this->memcache->add(self::getApp()->get_hostname() . ":" . $key, $value, $ttl);
 	}
 }
diff --git a/src/Core/Cache/MemcachedCacheDriver.php b/src/Core/Cache/MemcachedCacheDriver.php
index 78a4a6bdfe..dda36ba19c 100644
--- a/src/Core/Cache/MemcachedCacheDriver.php
+++ b/src/Core/Cache/MemcachedCacheDriver.php
@@ -10,10 +10,13 @@ use Friendica\Core\Cache;
  *
  * @author Hypolite Petovan <mrpetovan@gmail.com>
  */
-class MemcachedCacheDriver extends BaseObject implements ICacheDriver
+class MemcachedCacheDriver extends BaseObject implements IMemoryCacheDriver
 {
+	use TraitCompareSet;
+	use TraitCompareDelete;
+
 	/**
-	 * @var Memcached
+	 * @var \Memcached
 	 */
 	private $memcached;
 
@@ -46,14 +49,22 @@ class MemcachedCacheDriver extends BaseObject implements ICacheDriver
 		return $return;
 	}
 
-	public function set($key, $value, $duration = Cache::MONTH)
+	public function set($key, $value, $ttl = Cache::FIVE_MINUTES)
 	{
 		// We store with the hostname as key to avoid problems with other applications
-		return $this->memcached->set(
-			self::getApp()->get_hostname() . ':' . $key,
-			$value,
-			time() + $duration
-		);
+		if ($ttl > 0) {
+			return $this->memcached->set(
+				self::getApp()->get_hostname() . ':' . $key,
+				$value,
+				time() + $ttl
+			);
+		} else {
+			return $this->memcached->set(
+				self::getApp()->get_hostname() . ':' . $key,
+				$value
+			);
+		}
+
 	}
 
 	public function delete($key)
@@ -67,4 +78,17 @@ class MemcachedCacheDriver extends BaseObject implements ICacheDriver
 	{
 		return true;
 	}
+
+	/**
+	 * @brief Sets a value if it's not already stored
+	 *
+	 * @param string $key      The cache key
+	 * @param mixed  $value    The old value we know from the cache
+	 * @param int    $ttl      The cache lifespan, must be one of the Cache constants
+	 * @return bool
+	 */
+	public function add($key, $value, $ttl = Cache::FIVE_MINUTES)
+	{
+		return $this->memcached->add(self::getApp()->get_hostname() . ":" . $key, $value, $ttl);
+	}
 }
diff --git a/src/Core/Cache/RedisCacheDriver.php b/src/Core/Cache/RedisCacheDriver.php
index fa98842da0..735418b2d2 100644
--- a/src/Core/Cache/RedisCacheDriver.php
+++ b/src/Core/Cache/RedisCacheDriver.php
@@ -11,10 +11,10 @@ use Friendica\Core\Cache;
  * @author Hypolite Petovan <mrpetovan@gmail.com>
  * @author Roland Haeder <roland@mxchange.org>
  */
-class RedisCacheDriver extends BaseObject implements ICacheDriver
+class RedisCacheDriver extends BaseObject implements IMemoryCacheDriver
 {
 	/**
-	 * @var Redis
+	 * @var \Redis
 	 */
 	private $redis;
 
@@ -55,14 +55,21 @@ class RedisCacheDriver extends BaseObject implements ICacheDriver
 		return $return;
 	}
 
-	public function set($key, $value, $duration = Cache::MONTH)
+	public function set($key, $value, $ttl = Cache::FIVE_MINUTES)
 	{
 		// We store with the hostname as key to avoid problems with other applications
-		return $this->redis->set(
-			self::getApp()->get_hostname() . ":" . $key,
-			serialize($value),
-			time() + $duration
-		);
+		if ($ttl > 0) {
+			return $this->redis->setex(
+				self::getApp()->get_hostname() . ":" . $key,
+				time() + $ttl,
+				serialize($value)
+			);
+		} else {
+			return $this->redis->set(
+				self::getApp()->get_hostname() . ":" . $key,
+				serialize($value)
+			);
+		}
 	}
 
 	public function delete($key)
@@ -74,4 +81,60 @@ class RedisCacheDriver extends BaseObject implements ICacheDriver
 	{
 		return true;
 	}
+
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function add($key, $value, $ttl = Cache::FIVE_MINUTES)
+	{
+		if (!is_int($value)) {
+			$value = serialize($value);
+		}
+
+		return $this->redis->setnx(self::getApp()->get_hostname() . ":" . $key, $value);
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function compareSet($key, $oldValue, $newValue, $ttl = Cache::FIVE_MINUTES)
+	{
+		if (!is_int($newValue)) {
+			$newValue = serialize($newValue);
+		}
+
+		$this->redis->watch(self::getApp()->get_hostname() . ":" . $key);
+		// If the old value isn't what we expected, somebody else changed the key meanwhile
+		if ($this->get($key) === $oldValue) {
+			if ($ttl > 0) {
+				$result = $this->redis->multi()
+					->setex(self::getApp()->get_hostname() . ":" . $ttl, $key, $newValue)
+					->exec();
+			} else {
+				$result = $this->redis->multi()
+					->set(self::getApp()->get_hostname() . ":" . $key, $newValue)
+					->exec();
+			}
+			return $result !== false;
+		}
+		$this->redis->unwatch();
+		return false;
+	}
+	/**
+	 * (@inheritdoc)
+	 */
+	public function compareDelete($key, $value)
+	{
+		$this->redis->watch(self::getApp()->get_hostname() . ":" . $key);
+		// If the old value isn't what we expected, somebody else changed the key meanwhile
+		if ($this->get($key) === $value) {
+			$result = $this->redis->multi()
+				->del(self::getApp()->get_hostname() . ":" . $key)
+				->exec();
+			return $result !== false;
+		}
+		$this->redis->unwatch();
+		return false;
+	}
 }
diff --git a/src/Core/Cache/TraitCompareDelete.php b/src/Core/Cache/TraitCompareDelete.php
new file mode 100644
index 0000000000..ef59f69cd1
--- /dev/null
+++ b/src/Core/Cache/TraitCompareDelete.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace Friendica\Core\Cache;
+
+use Friendica\Core\Cache;
+
+/**
+ * Trait TraitCompareSetDelete
+ *
+ * This Trait is to compensate non native "exclusive" sets/deletes in caches
+ *
+ * @package Friendica\Core\Cache
+ */
+trait TraitCompareDelete
+{
+	abstract public function get($key);
+
+	abstract public function set($key, $value, $ttl = Cache::FIVE_MINUTES);
+
+	abstract public function delete($key);
+
+	abstract public function add($key, $value, $ttl = Cache::FIVE_MINUTES);
+
+	/**
+	 * NonNative - Compares if the old value is set and removes it
+	 *
+	 * @param string $key          The cache key
+	 * @param mixed  $value        The old value we know and want to delete
+	 * @return bool
+	 */
+	public function compareDelete($key, $value) {
+		if ($this->add($key . "_lock", true)) {
+			if ($this->get($key) === $value) {
+				$this->delete($key);
+				$this->delete($key . "_lock");
+				return true;
+			} else {
+				$this->delete($key . "_lock");
+				return false;
+			}
+		} else {
+			return false;
+		}
+	}
+}
diff --git a/src/Core/Cache/TraitCompareSet.php b/src/Core/Cache/TraitCompareSet.php
new file mode 100644
index 0000000000..77a6028355
--- /dev/null
+++ b/src/Core/Cache/TraitCompareSet.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Friendica\Core\Cache;
+
+use Friendica\Core\Cache;
+
+/**
+ * Trait TraitCompareSetDelete
+ *
+ * This Trait is to compensate non native "exclusive" sets/deletes in caches
+ *
+ * @package Friendica\Core\Cache
+ */
+trait TraitCompareSet
+{
+	abstract public function get($key);
+
+	abstract public function set($key, $value, $ttl = Cache::FIVE_MINUTES);
+
+	abstract public function delete($key);
+
+	abstract public function add($key, $value, $ttl = Cache::FIVE_MINUTES);
+
+	/**
+	 * NonNative - Compares if the old value is set and sets the new value
+	 *
+	 * @param string $key         The cache key
+	 * @param mixed  $oldValue    The old value we know from the cache
+	 * @param mixed  $newValue    The new value we want to set
+	 * @param int    $ttl      The cache lifespan, must be one of the Cache constants
+	 *
+	 * @return bool
+	 */
+	public function compareSet($key, $oldValue, $newValue, $ttl = Cache::FIVE_MINUTES) {
+		if ($this->add($key . "_lock", true)) {
+			if ($this->get($key) === $oldValue) {
+				$this->set($key, $newValue, $ttl);
+				$this->delete($key . "_lock");
+				return true;
+ 			} else {
+				$this->delete($key . "_lock");
+				return false;
+			}
+		} else {
+			return false;
+		}
+	}
+}
diff --git a/src/Core/Lock.php b/src/Core/Lock.php
new file mode 100644
index 0000000000..9892f1f4e4
--- /dev/null
+++ b/src/Core/Lock.php
@@ -0,0 +1,140 @@
+<?php
+
+namespace Friendica\Core;
+
+/**
+ * @file src/Core/Lock.php
+ * @brief Functions for preventing parallel execution of functions
+ */
+
+use Friendica\Core\Cache\CacheDriverFactory;
+use Friendica\Core\Cache\IMemoryCacheDriver;
+
+/**
+ * @brief This class contain Functions for preventing parallel execution of functions
+ */
+class Lock
+{
+	/**
+	 * @var Lock\ILockDriver;
+	 */
+	static $driver = null;
+
+	public static function init()
+	{
+		$lock_driver = Config::get('system', 'lock_driver', 'default');
+
+		try {
+			switch ($lock_driver) {
+				case 'memcache':
+				case 'memcached':
+				case 'redis':
+					$cache_driver = CacheDriverFactory::create($lock_driver);
+					if ($cache_driver instanceof IMemoryCacheDriver) {
+						self::$driver = new Lock\CacheLockDriver($cache_driver);
+					}
+					break;
+
+				case 'database':
+					self::$driver = new Lock\DatabaseLockDriver();
+					break;
+
+				case 'semaphore':
+					self::$driver = new Lock\SemaphoreLockDriver();
+					break;
+
+				default:
+					self::useAutoDriver();
+			}
+		} catch (\Exception $exception) {
+			logger ('Driver \'' . $lock_driver . '\' failed - Fallback to \'useAutoDriver()\'');
+			self::useAutoDriver();
+		}
+	}
+
+	/**
+	 * @brief This method tries to find the best - local - locking method for Friendica
+	 *
+	 * The following sequence will be tried:
+	 * 1. Semaphore Locking
+	 * 2. Cache Locking
+	 * 3. Database Locking
+	 *
+	 */
+	private static function useAutoDriver() {
+
+		// 1. Try to use Semaphores for - local - locking
+		if (function_exists('sem_get')) {
+			try {
+				self::$driver = new Lock\SemaphoreLockDriver();
+				return;
+			} catch (\Exception $exception) {
+				logger ('Using Semaphore driver for locking failed: ' . $exception->getMessage());
+			}
+		}
+
+		// 2. Try to use Cache Locking (don't use the DB-Cache Locking because it works different!)
+		$cache_driver = Config::get('system', 'cache_driver', 'database');
+		if ($cache_driver != 'database') {
+			try {
+				$lock_driver = CacheDriverFactory::create($cache_driver);
+				if ($lock_driver instanceof IMemoryCacheDriver) {
+					self::$driver = new Lock\CacheLockDriver($lock_driver);
+				}
+				return;
+			} catch (\Exception $exception) {
+				logger('Using Cache driver for locking failed: ' . $exception->getMessage());
+			}
+		}
+
+		// 3. Use Database Locking as a Fallback
+		self::$driver = new Lock\DatabaseLockDriver();
+	}
+
+	/**
+	 * Returns the current cache driver
+	 *
+	 * @return Lock\ILockDriver;
+	 */
+	private static function getDriver()
+	{
+		if (self::$driver === null) {
+			self::init();
+		}
+
+		return self::$driver;
+	}
+
+	/**
+	 * @brief Acquires a lock for a given name
+	 *
+	 * @param string  $key Name of the lock
+	 * @param integer $timeout Seconds until we give up
+	 *
+	 * @return boolean Was the lock successful?
+	 */
+	public static function acquire($key, $timeout = 120)
+	{
+		return self::getDriver()->acquireLock($key, $timeout);
+	}
+
+	/**
+	 * @brief Releases a lock if it was set by us
+	 *
+	 * @param string $key Name of the lock
+	 * @return void
+	 */
+	public static function release($key)
+	{
+		self::getDriver()->releaseLock($key);
+	}
+
+	/**
+	 * @brief Releases all lock that were set by us
+	 * @return void
+	 */
+	public static function releaseAll()
+	{
+		self::getDriver()->releaseAll();
+	}
+}
diff --git a/src/Core/Lock/AbstractLockDriver.php b/src/Core/Lock/AbstractLockDriver.php
new file mode 100644
index 0000000000..033d6f356e
--- /dev/null
+++ b/src/Core/Lock/AbstractLockDriver.php
@@ -0,0 +1,58 @@
+<?php
+
+namespace Friendica\Core\Lock;
+use Friendica\BaseObject;
+
+/**
+ * Class AbstractLockDriver
+ *
+ * @package Friendica\Core\Lock
+ *
+ * Basic class for Locking with common functions (local acquired locks, releaseAll, ..)
+ */
+abstract class AbstractLockDriver extends BaseObject implements ILockDriver
+{
+	/**
+	 * @var array The local acquired locks
+	 */
+	protected $acquiredLocks = [];
+
+	/**
+	 * Check if we've locally acquired a lock
+	 *
+	 * @param string key The Name of the lock
+	 * @return bool      Returns true if the lock is set
+	 */
+	protected function hasAcquiredLock($key) {
+		return isset($this->acquireLock[$key]) && $this->acquiredLocks[$key] === true;
+	}
+
+	/**
+	 * Mark a locally acquired lock
+	 *
+	 * @param string $key The Name of the lock
+	 */
+	protected function markAcquire($key) {
+		$this->acquiredLocks[$key] = true;
+	}
+
+	/**
+	 * Mark a release of a locally acquired lock
+	 *
+	 * @param string $key The Name of the lock
+	 */
+	protected function markRelease($key) {
+		unset($this->acquiredLocks[$key]);
+	}
+
+	/**
+	 * Releases all lock that were set by us
+	 *
+	 * @return void
+	 */
+	public function releaseAll() {
+		foreach ($this->acquiredLocks as $acquiredLock => $hasLock) {
+			$this->releaseLock($acquiredLock);
+		}
+	}
+}
diff --git a/src/Core/Lock/CacheLockDriver.php b/src/Core/Lock/CacheLockDriver.php
new file mode 100644
index 0000000000..2dd6f3fad9
--- /dev/null
+++ b/src/Core/Lock/CacheLockDriver.php
@@ -0,0 +1,88 @@
+<?php
+
+namespace Friendica\Core\Lock;
+
+use Friendica\Core\Cache\IMemoryCacheDriver;
+
+class CacheLockDriver extends AbstractLockDriver
+{
+	/**
+	 * @var \Friendica\Core\Cache\ICacheDriver;
+	 */
+	private $cache;
+
+	/**
+	 * CacheLockDriver constructor.
+	 *
+	 * @param IMemoryCacheDriver $cache The CacheDriver for this type of lock
+	 */
+	public function __construct(IMemoryCacheDriver $cache)
+	{
+		$this->cache = $cache;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function acquireLock($key, $timeout = 120)
+	{
+		$got_lock = false;
+		$start = time();
+
+		$cachekey = self::getCacheKey($key);
+
+		do {
+			$lock = $this->cache->get($cachekey);
+			// When we do want to lock something that was already locked by us.
+			if ((int)$lock == getmypid()) {
+				$got_lock = true;
+			}
+
+			// When we do want to lock something new
+			if (is_null($lock)) {
+				// At first initialize it with "0"
+				$this->cache->add($cachekey, 0);
+				// Now the value has to be "0" because otherwise the key was used by another process meanwhile
+				if ($this->cache->compareSet($cachekey, 0, getmypid(), 300)) {
+					$got_lock = true;
+					$this->markAcquire($key);
+				}
+			}
+
+			if (!$got_lock && ($timeout > 0)) {
+				usleep(rand(10000, 200000));
+			}
+		} while (!$got_lock && ((time() - $start) < $timeout));
+
+		return $got_lock;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function releaseLock($key)
+	{
+		$cachekey = self::getCacheKey($key);
+
+		$this->cache->compareDelete($cachekey, getmypid());
+		$this->markRelease($key);
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function isLocked($key)
+	{
+		$cachekey = self::getCacheKey($key);
+		$lock = $this->cache->get($cachekey);
+		return isset($lock) && ($lock !== false);
+	}
+
+	/**
+	 * @param string $key	The original key
+	 * @return string		The cache key used for the cache
+	 */
+	private static function getCacheKey($key) {
+		return self::getApp()->get_hostname() . ";lock:" . $key;
+	}
+}
diff --git a/src/Core/Lock/DatabaseLockDriver.php b/src/Core/Lock/DatabaseLockDriver.php
new file mode 100644
index 0000000000..6f4b942a4d
--- /dev/null
+++ b/src/Core/Lock/DatabaseLockDriver.php
@@ -0,0 +1,90 @@
+<?php
+
+namespace Friendica\Core\Lock;
+
+use dba;
+use Friendica\Database\DBM;
+use Friendica\Util\DateTimeFormat;
+
+/**
+ * Locking driver that stores the locks in the database
+ */
+class DatabaseLockDriver extends AbstractLockDriver
+{
+	/**
+	 * (@inheritdoc)
+	 */
+	public function acquireLock($key, $timeout = 120)
+	{
+		$got_lock = false;
+		$start = time();
+
+		do {
+			dba::lock('locks');
+			$lock = dba::selectFirst('locks', ['locked', 'pid'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
+
+			if (DBM::is_result($lock)) {
+				if ($lock['locked']) {
+					// We want to lock something that was already locked by us? So we got the lock.
+					if ($lock['pid'] == getmypid()) {
+						$got_lock = true;
+						$this->markAcquire($key);
+					}
+				}
+				if (!$lock['locked']) {
+					dba::update('locks', ['locked' => true, 'pid' => getmypid(), 'expires' => DateTimeFormat::utc('now + 300seconds')], ['name' => $key]);
+					$got_lock = true;
+					$this->markAcquire($key);
+				}
+			} else {
+				dba::insert('locks', ['name' => $key, 'locked' => true, 'pid' => getmypid(), 'expires' => DateTimeFormat::utc('now + 300seconds')]);
+				$got_lock = true;
+				$this->markAcquire($key);
+			}
+
+			dba::unlock();
+
+			if (!$got_lock && ($timeout > 0)) {
+				usleep(rand(100000, 2000000));
+			}
+		} while (!$got_lock && ((time() - $start) < $timeout));
+
+		return $got_lock;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function releaseLock($key)
+	{
+		dba::delete('locks', ['name' => $key, 'pid' => getmypid()]);
+
+		$this->markRelease($key);
+
+		return;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function releaseAll()
+	{
+		dba::delete('locks', ['pid' => getmypid()]);
+
+		$this->acquiredLocks = [];
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function isLocked($key)
+	{
+		$lock = dba::selectFirst('locks', ['locked'], ['`name` = ? AND `expires` >= ?', $key, DateTimeFormat::utcNow()]);
+
+		if (DBM::is_result($lock)) {
+			return $lock['locked'] !== false;
+		} else {
+			return false;
+		}
+	}
+}
diff --git a/src/Core/Lock/ILockDriver.php b/src/Core/Lock/ILockDriver.php
new file mode 100644
index 0000000000..cd54cc03c3
--- /dev/null
+++ b/src/Core/Lock/ILockDriver.php
@@ -0,0 +1,46 @@
+<?php
+
+namespace Friendica\Core\Lock;
+
+/**
+ * Lock Driver Interface
+ *
+ * @author Philipp Holzer <admin@philipp.info>
+ */
+interface ILockDriver
+{
+	/**
+	 * Checks, if a key is currently locked to a or my process
+	 *
+	 * @param string $key 		The name of the lock
+	 * @return bool
+	 */
+	public function isLocked($key);
+
+	/**
+	 *
+	 * Acquires a lock for a given name
+	 *
+	 * @param string  $key      The Name of the lock
+	 * @param integer $timeout  Seconds until we give up
+	 *
+	 * @return boolean Was the lock successful?
+	 */
+	public function acquireLock($key, $timeout = 120);
+
+	/**
+	 * Releases a lock if it was set by us
+	 *
+	 * @param string $key The Name of the lock
+	 *
+	 * @return void
+	 */
+	public function releaseLock($key);
+
+	/**
+	 * Releases all lock that were set by us
+	 *
+	 * @return void
+	 */
+	public function releaseAll();
+}
diff --git a/src/Core/Lock/SemaphoreLockDriver.php b/src/Core/Lock/SemaphoreLockDriver.php
new file mode 100644
index 0000000000..d032d46cc6
--- /dev/null
+++ b/src/Core/Lock/SemaphoreLockDriver.php
@@ -0,0 +1,71 @@
+<?php
+
+namespace Friendica\Core\Lock;
+
+class SemaphoreLockDriver extends AbstractLockDriver
+{
+	private static $semaphore = [];
+
+	public function __construct()
+	{
+		if (!function_exists('sem_get')) {
+			throw new \Exception('Semaphore lock not supported');
+		}
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	private static function semaphoreKey($key)
+	{
+		$temp = get_temppath();
+
+		$file = $temp . '/' . $key . '.sem';
+
+		if (!file_exists($file)) {
+			file_put_contents($file, $key);
+		}
+
+		return ftok($file, 'f');
+	}
+
+	/**
+	 *
+	 * (@inheritdoc)
+	 */
+	public function acquireLock($key, $timeout = 120)
+	{
+		self::$semaphore[$key] = sem_get(self::semaphoreKey($key));
+		if (self::$semaphore[$key]) {
+			if (sem_acquire(self::$semaphore[$key], ($timeout == 0))) {
+				$this->markAcquire($key);
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function releaseLock($key)
+	{
+		if (empty(self::$semaphore[$key])) {
+			return false;
+		} else {
+			$success = @sem_release(self::$semaphore[$key]);
+			unset(self::$semaphore[$key]);
+			$this->markRelease($key);
+			return $success;
+		}
+	}
+
+	/**
+	 * (@inheritdoc)
+	 */
+	public function isLocked($key)
+	{
+		return isset(self::$semaphore[$key]);
+	}
+}
diff --git a/src/Core/Worker.php b/src/Core/Worker.php
index c965e05830..c4c91bbf8b 100644
--- a/src/Core/Worker.php
+++ b/src/Core/Worker.php
@@ -4,15 +4,11 @@
  */
 namespace Friendica\Core;
 
-use Friendica\Core\Addon;
-use Friendica\Core\Config;
-use Friendica\Core\System;
+use dba;
 use Friendica\Database\DBM;
 use Friendica\Model\Process;
 use Friendica\Util\DateTimeFormat;
-use Friendica\Util\Lock;
 use Friendica\Util\Network;
-use dba;
 
 require_once 'include/dba.php';
 
@@ -108,16 +104,16 @@ class Worker
 				}
 
 				// If possible we will fetch new jobs for this worker
-				if (!$refetched && Lock::set('worker_process', 0)) {
+				if (!$refetched && Lock::acquire('worker_process', 0)) {
 					$stamp = (float)microtime(true);
 					$refetched = self::findWorkerProcesses($passing_slow);
 					self::$db_duration += (microtime(true) - $stamp);
-					Lock::remove('worker_process');
+					Lock::release('worker_process');
 				}
 			}
 
 			// To avoid the quitting of multiple workers only one worker at a time will execute the check
-			if (Lock::set('worker', 0)) {
+			if (Lock::acquire('worker', 0)) {
 				$stamp = (float)microtime(true);
 				// Count active workers and compare them with a maximum value that depends on the load
 				if (self::tooMuchWorkers()) {
@@ -130,7 +126,7 @@ class Worker
 					logger('Memory limit reached, quitting.', LOGGER_DEBUG);
 					return;
 				}
-				Lock::remove('worker');
+				Lock::release('worker');
 				self::$db_duration += (microtime(true) - $stamp);
 			}
 
@@ -883,7 +879,7 @@ class Worker
 		dba::close($r);
 
 		$stamp = (float)microtime(true);
-		if (!Lock::set('worker_process')) {
+		if (!Lock::acquire('worker_process')) {
 			return false;
 		}
 		self::$lock_duration = (microtime(true) - $stamp);
@@ -892,7 +888,7 @@ class Worker
 		$found = self::findWorkerProcesses($passing_slow);
 		self::$db_duration += (microtime(true) - $stamp);
 
-		Lock::remove('worker_process');
+		Lock::release('worker_process');
 
 		if ($found) {
 			$r = dba::select('workerqueue', [], ['pid' => getmypid(), 'done' => false]);
@@ -1097,13 +1093,13 @@ class Worker
 		}
 
 		// If there is a lock then we don't have to check for too much worker
-		if (!Lock::set('worker', 0)) {
+		if (!Lock::acquire('worker', 0)) {
 			return true;
 		}
 
 		// If there are already enough workers running, don't fork another one
 		$quit = self::tooMuchWorkers();
-		Lock::remove('worker');
+		Lock::release('worker');
 
 		if ($quit) {
 			return true;
diff --git a/src/Database/DBStructure.php b/src/Database/DBStructure.php
index db6997ec62..d3ce350a72 100644
--- a/src/Database/DBStructure.php
+++ b/src/Database/DBStructure.php
@@ -4,10 +4,9 @@
  */
 namespace Friendica\Database;
 
+use dba;
 use Friendica\Core\Config;
 use Friendica\Core\L10n;
-use Friendica\Database\DBM;
-use dba;
 
 require_once 'boot.php';
 require_once 'include/dba.php';
@@ -1283,9 +1282,11 @@ class DBStructure
 						"name" => ["type" => "varchar(128)", "not null" => "1", "default" => "", "comment" => ""],
 						"locked" => ["type" => "boolean", "not null" => "1", "default" => "0", "comment" => ""],
 						"pid" => ["type" => "int unsigned", "not null" => "1", "default" => "0", "comment" => "Process ID"],
-						],
+						"expires" => ["type" => "datetime", "not null" => "1", "default" => NULL_DATE, "comment" => "datetime of cache expiration"],
+				],
 				"indexes" => [
 						"PRIMARY" => ["id"],
+						"name_expires" => ["name", "expires"]
 						]
 				];
 		$database["mail"] = [
diff --git a/src/Model/Item.php b/src/Model/Item.php
index ac53bb0220..d31d7c1323 100644
--- a/src/Model/Item.php
+++ b/src/Model/Item.php
@@ -6,26 +6,22 @@
 
 namespace Friendica\Model;
 
+use dba;
 use Friendica\BaseObject;
 use Friendica\Content\Text;
 use Friendica\Core\Addon;
 use Friendica\Core\Config;
 use Friendica\Core\L10n;
+use Friendica\Core\Lock;
 use Friendica\Core\PConfig;
 use Friendica\Core\System;
 use Friendica\Core\Worker;
 use Friendica\Database\DBM;
-use Friendica\Model\Contact;
-use Friendica\Model\Conversation;
-use Friendica\Model\Group;
-use Friendica\Model\Term;
 use Friendica\Object\Image;
 use Friendica\Protocol\Diaspora;
 use Friendica\Protocol\OStatus;
 use Friendica\Util\DateTimeFormat;
 use Friendica\Util\XML;
-use Friendica\Util\Lock;
-use dba;
 use Text_LanguageDetect;
 
 require_once 'boot.php';
@@ -1595,7 +1591,7 @@ class Item extends BaseObject
 		}
 
 		// To avoid timing problems, we are using locks.
-		$locked = Lock::set('item_insert_content');
+		$locked = Lock::acquire('item_insert_content');
 		if (!$locked) {
 			logger("Couldn't acquire lock for URI " . $item['uri'] . " - proceeding anyway.");
 		}
@@ -1615,7 +1611,7 @@ class Item extends BaseObject
 			logger('Could not insert content for URI ' . $item['uri'] . ' - trying asynchronously');
 		}
 		if ($locked) {
-			Lock::remove('item_insert_content');
+			Lock::release('item_insert_content');
 		}
 	}
 
diff --git a/src/Protocol/OStatus.php b/src/Protocol/OStatus.php
index 5a30bfd2c3..dadc19dcca 100644
--- a/src/Protocol/OStatus.php
+++ b/src/Protocol/OStatus.php
@@ -4,11 +4,15 @@
  */
 namespace Friendica\Protocol;
 
+use dba;
+use DOMDocument;
+use DOMXPath;
 use Friendica\Content\Text\BBCode;
 use Friendica\Content\Text\HTML;
 use Friendica\Core\Cache;
 use Friendica\Core\Config;
 use Friendica\Core\L10n;
+use Friendica\Core\Lock;
 use Friendica\Core\System;
 use Friendica\Database\DBM;
 use Friendica\Model\Contact;
@@ -19,12 +23,8 @@ use Friendica\Model\User;
 use Friendica\Network\Probe;
 use Friendica\Object\Image;
 use Friendica\Util\DateTimeFormat;
-use Friendica\Util\Lock;
 use Friendica\Util\Network;
 use Friendica\Util\XML;
-use dba;
-use DOMDocument;
-use DOMXPath;
 
 require_once 'include/dba.php';
 require_once 'include/items.php';
@@ -513,9 +513,9 @@ class OStatus
 							logger("Item with uri ".$item["uri"]." is from a blocked contact.", LOGGER_DEBUG);
 						} else {
 							// We are having duplicated entries. Hopefully this solves it.
-							if (Lock::set('ostatus_process_item_insert')) {
+							if (Lock::acquire('ostatus_process_item_insert')) {
 								$ret = Item::insert($item);
-								Lock::remove('ostatus_process_item_insert');
+								Lock::release('ostatus_process_item_insert');
 								logger("Item with uri ".$item["uri"]." for user ".$importer["uid"].' stored. Return value: '.$ret);
 							} else {
 								$ret = Item::insert($item);
diff --git a/src/Util/Lock.php b/src/Util/Lock.php
deleted file mode 100644
index eba264ad93..0000000000
--- a/src/Util/Lock.php
+++ /dev/null
@@ -1,211 +0,0 @@
-<?php
-/**
- * @file src/Util/Lock.php
- */
-namespace Friendica\Util;
-
-/**
- * @file src/Util/Lock.php
- * @brief Functions for preventing parallel execution of functions
- */
-
-use Friendica\Core\Config;
-use Friendica\Database\DBM;
-use Memcache;
-use dba;
-
-require_once 'include/dba.php';
-
-/**
- * @brief This class contain Functions for preventing parallel execution of functions
- */
-class Lock
-{
-	private static $semaphore = [];
-
-	/**
-	 * @brief Check for memcache and open a connection if configured
-	 *
-	 * @return object|boolean The memcache object - or "false" if not successful
-	 */
-	private static function connectMemcache()
-	{
-		if (!function_exists('memcache_connect')) {
-			return false;
-		}
-
-		if (!Config::get('system', 'memcache')) {
-			return false;
-		}
-
-		$memcache_host = Config::get('system', 'memcache_host', '127.0.0.1');
-		$memcache_port = Config::get('system', 'memcache_port', 11211);
-
-		$memcache = new Memcache;
-
-		if (!$memcache->connect($memcache_host, $memcache_port)) {
-			return false;
-		}
-
-		return $memcache;
-	}
-
-	/**
-	 * @brief Creates a semaphore key
-	 *
-	 * @param string $fn_name Name of the lock
-	 *
-	 * @return ressource the semaphore key
-	 */
-	private static function semaphoreKey($fn_name)
-	{
-		$temp = get_temppath();
-
-		$file = $temp.'/'.$fn_name.'.sem';
-
-		if (!file_exists($file)) {
-			file_put_contents($file, $fn_name);
-		}
-
-		return ftok($file, 'f');
-	}
-
-	/**
-	 * @brief Sets a lock for a given name
-	 *
-	 * @param string  $fn_name Name of the lock
-	 * @param integer $timeout Seconds until we give up
-	 *
-	 * @return boolean Was the lock successful?
-	 */
-	public static function set($fn_name, $timeout = 120)
-	{
-		$got_lock = false;
-		$start = time();
-
-		// The second parameter for "sem_acquire" doesn't exist before 5.6.1
-		if (function_exists('sem_get') && version_compare(PHP_VERSION, '5.6.1', '>=')) {
-			self::$semaphore[$fn_name] = sem_get(self::semaphoreKey($fn_name));
-			if (self::$semaphore[$fn_name]) {
-				return sem_acquire(self::$semaphore[$fn_name], ($timeout == 0));
-			}
-		}
-
-		$memcache = self::connectMemcache();
-		if (is_object($memcache)) {
-			$cachekey = get_app()->get_hostname().";lock:".$fn_name;
-
-			do {
-				// We only lock to be sure that nothing happens at exactly the same time
-				dba::lock('locks');
-				$lock = $memcache->get($cachekey);
-
-				if (!is_bool($lock)) {
-					$pid = (int)$lock;
-
-					// When the process id isn't used anymore, we can safely claim the lock for us.
-					// Or we do want to lock something that was already locked by us.
-					if (!posix_kill($pid, 0) || ($pid == getmypid())) {
-						$lock = false;
-					}
-				}
-				if (is_bool($lock)) {
-					$memcache->set($cachekey, getmypid(), MEMCACHE_COMPRESSED, 300);
-					$got_lock = true;
-				}
-
-				dba::unlock();
-
-				if (!$got_lock && ($timeout > 0)) {
-					usleep(rand(10000, 200000));
-				}
-			} while (!$got_lock && ((time() - $start) < $timeout));
-
-			return $got_lock;
-		}
-
-		do {
-			dba::lock('locks');
-			$lock = dba::selectFirst('locks', ['locked', 'pid'], ['name' => $fn_name]);
-
-			if (DBM::is_result($lock)) {
-				if ($lock['locked']) {
-					// When the process id isn't used anymore, we can safely claim the lock for us.
-					if (!posix_kill($lock['pid'], 0)) {
-						$lock['locked'] = false;
-					}
-					// We want to lock something that was already locked by us? So we got the lock.
-					if ($lock['pid'] == getmypid()) {
-						$got_lock = true;
-					}
-				}
-				if (!$lock['locked']) {
-					dba::update('locks', ['locked' => true, 'pid' => getmypid()], ['name' => $fn_name]);
-					$got_lock = true;
-				}
-			} elseif (!DBM::is_result($lock)) {
-				dba::insert('locks', ['name' => $fn_name, 'locked' => true, 'pid' => getmypid()]);
-				$got_lock = true;
-			}
-
-			dba::unlock();
-
-			if (!$got_lock && ($timeout > 0)) {
-				usleep(rand(100000, 2000000));
-			}
-		} while (!$got_lock && ((time() - $start) < $timeout));
-
-		return $got_lock;
-	}
-
-	/**
-	 * @brief Removes a lock if it was set by us
-	 *
-	 * @param string $fn_name Name of the lock
-	 * @return mixed
-	 */
-	public static function remove($fn_name)
-	{
-		if (function_exists('sem_get') && version_compare(PHP_VERSION, '5.6.1', '>=')) {
-			if (empty(self::$semaphore[$fn_name])) {
-				return false;
-			} else {
-				$success = @sem_release(self::$semaphore[$fn_name]);
-				unset(self::$semaphore[$fn_name]);
-				return $success;
-			}
-		}
-
-		$memcache = self::connectMemcache();
-		if (is_object($memcache)) {
-			$cachekey = get_app()->get_hostname().";lock:".$fn_name;
-			$lock = $memcache->get($cachekey);
-
-			if (!is_bool($lock)) {
-				if ((int)$lock == getmypid()) {
-					$memcache->delete($cachekey);
-				}
-			}
-			return;
-		}
-
-		dba::update('locks', ['locked' => false, 'pid' => 0], ['name' => $fn_name, 'pid' => getmypid()]);
-		return;
-	}
-
-	/**
-	 * @brief Removes all lock that were set by us
-	 * @return void
-	 */
-	public static function removeAll()
-	{
-		$memcache = self::connectMemcache();
-		if (is_object($memcache)) {
-			// We cannot delete all cache entries, but this doesn't matter with memcache
-			return;
-		}
-
-		dba::update('locks', ['locked' => false, 'pid' => 0], ['pid' => getmypid()]);
-		return;
-	}
-}
diff --git a/tests/datasets/api.yml b/tests/datasets/api.yml
index 9ba5ec387e..14053c3e86 100644
--- a/tests/datasets/api.yml
+++ b/tests/datasets/api.yml
@@ -14,7 +14,7 @@ user:
         uid: 42
         username: Test user
         nickname: selfcontact
-        verified: true
+        verified: 1
         password: $2y$10$DLRNTRmJgKe1cSrFJ5Jb0edCqvXlA9sh/RHdSnfxjbR.04yZRm4Qm
         theme: frio
 
@@ -24,12 +24,12 @@ contact:
         uid: 42
         name: Self contact
         nick: selfcontact
-        self: true
+        self: 1
         nurl: http://localhost/profile/selfcontact
         url: http://localhost/profile/selfcontact
         about: User used in tests
-        pending: false
-        blocked: false
+        pending: 0
+        blocked: 0
         rel: 1
         network: dfrn
     -
@@ -39,11 +39,11 @@ contact:
         # the fallback to api_get_nick() in api_get_user()
         name: othercontact
         nick: othercontact
-        self: false
+        self: 0
         nurl: http://localhost/profile/othercontact
         url: http://localhost/profile/othercontact
-        pending: false
-        blocked: false
+        pending: 0
+        blocked: 0
         rel: 0
         network: dfrn
     -
@@ -51,150 +51,150 @@ contact:
         uid: 0
         name: Friend contact
         nick: friendcontact
-        self: false
+        self: 0
         nurl: http://localhost/profile/friendcontact
         url: http://localhost/profile/friendcontact
-        pending: false
-        blocked: false
+        pending: 0
+        blocked: 0
         rel: 2
         network: dfrn
 
 item:
     -
         id: 1
-        visible: true
+        visible: 1
         contact-id: 42
         author-id: 42
         owner-id: 45
         uid: 42
         verb: http://activitystrea.ms/schema/1.0/post
-        unseen: true
+        unseen: 1
         body: Parent status
         parent: 1
         author-link: http://localhost/profile/selfcontact
-        wall: true
-        starred: true
-        origin: true
+        wall: 1
+        starred: 1
+        origin: 1
         allow_cid: ''
         allow_gid: ''
         deny_cid: ''
         deny_gid: ''
     -
         id: 2
-        visible: true
+        visible: 1
         contact-id: 42
         author-id: 42
         owner-id: 45
         uid: 42
         verb: http://activitystrea.ms/schema/1.0/post
-        unseen: false
+        unseen: 0
         body: Reply
         parent: 1
         author-link: http://localhost/profile/selfcontact
-        wall: true
-        starred: false
-        origin: true
+        wall: 1
+        starred: 0
+        origin: 1
     -
         id: 3
-        visible: true
+        visible: 1
         contact-id: 43
         author-id: 43
         owner-id: 42
         uid: 42
         verb: http://activitystrea.ms/schema/1.0/post
-        unseen: false
+        unseen: 0
         body: Other user status
         parent: 3
         author-link: http://localhost/profile/othercontact
-        wall: true
-        starred: false
-        origin: true
+        wall: 1
+        starred: 0
+        origin: 1
     -
         id: 4
-        visible: true
+        visible: 1
         contact-id: 44
         author-id: 44
         owner-id: 42
         uid: 42
         verb: http://activitystrea.ms/schema/1.0/post
-        unseen: false
+        unseen: 0
         body: Friend user reply
         parent: 1
         author-link: http://localhost/profile/othercontact
-        wall: true
-        starred: false
-        origin: true
+        wall: 1
+        starred: 0
+        origin: 1
     -
         id: 5
-        visible: true
+        visible: 1
         contact-id: 42
         author-id: 42
         owner-id: 42
         uid: 42
         verb: http://activitystrea.ms/schema/1.0/post
-        unseen: false
+        unseen: 0
         body: '[share]Shared status[/share]'
         parent: 1
         author-link: http://localhost/profile/othercontact
-        wall: true
-        starred: false
-        origin: true
+        wall: 1
+        starred: 0
+        origin: 1
         allow_cid: ''
         allow_gid: ''
         deny_cid: ''
         deny_gid: ''
     -
         id: 6
-        visible: true
+        visible: 1
         contact-id: 44
         author-id: 44
         owner-id: 42
         uid: 42
         verb: http://activitystrea.ms/schema/1.0/post
-        unseen: false
+        unseen: 0
         body: Friend user status
         parent: 6
         author-link: http://localhost/profile/othercontact
-        wall: true
-        starred: false
-        origin: true
+        wall: 1
+        starred: 0
+        origin: 1
 
 thread:
     -
         iid: 1
-        visible: true
+        visible: 1
         contact-id: 42
         author-id: 42
         owner-id: 42
         uid: 42
-        wall: true
+        wall: 1
     -
         iid: 3
-        visible: true
+        visible: 1
         contact-id: 43
         author-id: 43
         owner-id: 43
         uid: 0
-        wall: true
+        wall: 1
     -
         iid: 6
-        visible: true
+        visible: 1
         contact-id: 44
         author-id: 44
         owner-id: 44
         uid: 0
-        wall: true
+        wall: 1
 
 group:
     -
         id: 1
         uid: 42
-        visible: true
+        visible: 1
         name: Visible list
     -
         id: 2
         uid: 42
-        visible: false
+        visible: 0
         name: Private list
 
 search:
diff --git a/tests/src/Core/Lock/CacheLockDriverTest.php b/tests/src/Core/Lock/CacheLockDriverTest.php
new file mode 100644
index 0000000000..a089059725
--- /dev/null
+++ b/tests/src/Core/Lock/CacheLockDriverTest.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Friendica\Test\src\Core\Lock;
+
+
+use Friendica\Core\Cache\ArrayCache;
+use Friendica\Core\Lock\CacheLockDriver;
+
+class CacheLockDriverTest extends LockTest
+{
+	/**
+	 * @var \Friendica\Core\Cache\IMemoryCacheDriver
+	 */
+	private $cache;
+
+	protected function getInstance()
+	{
+		$this->cache = new ArrayCache();
+		return new CacheLockDriver($this->cache);
+	}
+
+	public function tearDown()
+	{
+		$this->cache->clear();
+		parent::tearDown();
+	}
+}
\ No newline at end of file
diff --git a/tests/src/Core/Lock/DatabaseLockDriverTest.php b/tests/src/Core/Lock/DatabaseLockDriverTest.php
new file mode 100644
index 0000000000..a80ff4c37c
--- /dev/null
+++ b/tests/src/Core/Lock/DatabaseLockDriverTest.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace Friendica\Test\src\Core\Lock;
+
+use dba;
+use Friendica\Core\Lock\DatabaseLockDriver;
+use Friendica\Database\DBStructure;
+use PHPUnit\DbUnit\DataSet\YamlDataSet;
+use PHPUnit\DbUnit\TestCaseTrait;
+use PHPUnit_Extensions_Database_DB_IDatabaseConnection;
+
+class DatabaseLockDriverTest extends LockTest
+{
+	use TestCaseTrait;
+
+	/**
+	 * Get database connection.
+	 *
+	 * This function is executed before each test in order to get a database connection that can be used by tests.
+	 * If no prior connection is available, it tries to create one using the USER, PASS and DB environment variables.
+	 *
+	 * If it could not connect to the database, the test is skipped.
+	 *
+	 * @return PHPUnit_Extensions_Database_DB_IDatabaseConnection
+	 * @see https://phpunit.de/manual/5.7/en/database.html
+	 */
+	protected function getConnection()
+	{
+		if (!dba::$connected) {
+			dba::connect('localhost', getenv('USER'), getenv('PASS'), getenv('DB'));
+
+			if (dba::$connected) {
+				$app = get_app();
+				// We need to do this in order to disable logging
+				$app->module = 'install';
+
+				// Create database structure
+				DBStructure::update(false, true, true);
+			} else {
+				$this->markTestSkipped('Could not connect to the database.');
+			}
+		}
+
+		return $this->createDefaultDBConnection(dba::get_db(), getenv('DB'));
+	}
+
+	/**
+	 * Get dataset to populate the database with.
+	 * @return YamlDataSet
+	 * @see https://phpunit.de/manual/5.7/en/database.html
+	 */
+	protected function getDataSet()
+	{
+		return new YamlDataSet(__DIR__ . '/../../../datasets/api.yml');
+	}
+
+	protected function getInstance()
+	{
+		return new DatabaseLockDriver();
+	}
+
+	public function tearDown()
+	{
+		dba::delete('locks', [ 'id > 0']);
+		parent::tearDown();
+	}
+}
\ No newline at end of file
diff --git a/tests/src/Core/Lock/LockTest.php b/tests/src/Core/Lock/LockTest.php
new file mode 100644
index 0000000000..c8c0c32ae2
--- /dev/null
+++ b/tests/src/Core/Lock/LockTest.php
@@ -0,0 +1,80 @@
+<?php
+
+namespace Friendica\Test\src\Core\Lock;
+
+use Friendica\App;
+use Friendica\Core\Config;
+use PHPUnit\Framework\TestCase;
+
+abstract class LockTest extends TestCase
+{
+	/**
+	 * @var \Friendica\Core\Lock\ILockDriver
+	 */
+	protected $instance;
+
+	abstract protected function getInstance();
+
+	protected function setUp()
+	{
+		global $a;
+		parent::setUp();
+		$this->instance = $this->getInstance();
+
+		// Reusable App object
+		$this->app = new App(__DIR__.'/../');
+		$a = $this->app;
+
+		// Default config
+		Config::set('config', 'hostname', 'localhost');
+		Config::set('system', 'throttle_limit_day', 100);
+		Config::set('system', 'throttle_limit_week', 100);
+		Config::set('system', 'throttle_limit_month', 100);
+		Config::set('system', 'theme', 'system_theme');
+	}
+
+	public function testLock() {
+		$this->instance->acquireLock('foo', 1);
+		$this->assertTrue($this->instance->isLocked('foo'));
+		$this->assertFalse($this->instance->isLocked('bar'));
+	}
+
+	public function testDoubleLock() {
+		$this->instance->acquireLock('foo', 1);
+		$this->assertTrue($this->instance->isLocked('foo'));
+		// We already locked it
+		$this->assertTrue($this->instance->acquireLock('foo', 1));
+	}
+
+	public function testReleaseLock() {
+		$this->instance->acquireLock('foo', 1);
+		$this->assertTrue($this->instance->isLocked('foo'));
+		$this->instance->releaseLock('foo');
+		$this->assertFalse($this->instance->isLocked('foo'));
+	}
+
+	public function testReleaseAll() {
+		$this->instance->acquireLock('foo', 1);
+		$this->instance->acquireLock('bar', 1);
+		$this->instance->acquireLock('nice', 1);
+
+		$this->instance->releaseAll();
+
+		$this->assertFalse($this->instance->isLocked('foo'));
+		$this->assertFalse($this->instance->isLocked('bar'));
+		$this->assertFalse($this->instance->isLocked('nice'));
+	}
+
+	public function testReleaseAfterUnlock() {
+		$this->instance->acquireLock('foo', 1);
+		$this->instance->acquireLock('bar', 1);
+		$this->instance->acquireLock('nice', 1);
+
+		$this->instance->releaseLock('foo');
+
+		$this->instance->releaseAll();
+
+		$this->assertFalse($this->instance->isLocked('bar'));
+		$this->assertFalse($this->instance->isLocked('#/$%§'));
+	}
+}
\ No newline at end of file
diff --git a/tests/src/Core/Lock/SemaphoreLockDriverTest.php b/tests/src/Core/Lock/SemaphoreLockDriverTest.php
new file mode 100644
index 0000000000..56c96458f2
--- /dev/null
+++ b/tests/src/Core/Lock/SemaphoreLockDriverTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Friendica\Test\src\Core\Lock;
+
+
+use Friendica\Core\Lock\SemaphoreLockDriver;
+
+class SemaphoreLockDriverTest extends LockTest
+{
+	/**
+	 * @var \Friendica\Core\Lock\SemaphoreLockDriver
+	 */
+	private $semaphoreLockDriver;
+
+	protected function getInstance()
+	{
+		$this->semaphoreLockDriver = new SemaphoreLockDriver();
+		return $this->semaphoreLockDriver;
+	}
+
+	public function tearDown()
+	{
+		$this->semaphoreLockDriver->releaseAll();
+		parent::tearDown();
+	}
+}
\ No newline at end of file