From 29213b6136a4b2f71e5f981e9bc08e3e76128d4e Mon Sep 17 00:00:00 2001
From: Robin Appelman <icewind@owncloud.com>
Date: Tue, 28 Apr 2015 15:39:38 +0200
Subject: [PATCH 1/6] extends memcache with add, inc and dec

---
 lib/private/memcache/apc.php        | 39 ++++++++++++++++-
 lib/private/memcache/arraycache.php | 56 +++++++++++++++++++++++-
 lib/private/memcache/memcached.php  | 39 ++++++++++++++++-
 lib/private/memcache/redis.php      | 54 ++++++++++++++++++++---
 lib/private/memcache/xcache.php     | 66 ++++++++++++++++++++++------
 lib/public/imemcache.php            | 68 +++++++++++++++++++++++++++++
 tests/lib/memcache/cache.php        | 36 +++++++++++++++
 7 files changed, 336 insertions(+), 22 deletions(-)
 create mode 100644 lib/public/imemcache.php

diff --git a/lib/private/memcache/apc.php b/lib/private/memcache/apc.php
index b8b2b608124..ba16972e6d6 100644
--- a/lib/private/memcache/apc.php
+++ b/lib/private/memcache/apc.php
@@ -24,7 +24,9 @@
 
 namespace OC\Memcache;
 
-class APC extends Cache {
+use OCP\IMemcache;
+
+class APC extends Cache implements IMemcache {
 	public function get($key) {
 		$result = apc_fetch($this->getPrefix() . $key, $success);
 		if (!$success) {
@@ -52,6 +54,41 @@ class APC extends Cache {
 		return apc_delete($iter);
 	}
 
+	/**
+	 * Set a value in the cache if it's not already stored
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 * @param int $ttl Time To Live in seconds. Defaults to 60*60*24
+	 * @return bool
+	 */
+	public function add($key, $value, $ttl = 0) {
+		return apc_add($this->getPrefix() . $key, $value, $ttl);
+	}
+
+	/**
+	 * Increase a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function inc($key, $step = 1) {
+		$this->add($key, 0);
+		return apc_inc($this->getPrefix() . $key, $step);
+	}
+
+	/**
+	 * Decrease a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function dec($key, $step = 1) {
+		return apc_dec($this->getPrefix() . $key, $step);
+	}
+
 	static public function isAvailable() {
 		if (!extension_loaded('apc')) {
 			return false;
diff --git a/lib/private/memcache/arraycache.php b/lib/private/memcache/arraycache.php
index 939472dc518..6db920a69a8 100644
--- a/lib/private/memcache/arraycache.php
+++ b/lib/private/memcache/arraycache.php
@@ -22,7 +22,9 @@
 
 namespace OC\Memcache;
 
-class ArrayCache extends Cache {
+use OCP\IMemcache;
+
+class ArrayCache extends Cache implements IMemcache {
 	/** @var array Array with the cached data */
 	protected $cachedData = array();
 
@@ -76,6 +78,58 @@ class ArrayCache extends Cache {
 		return true;
 	}
 
+	/**
+	 * Set a value in the cache if it's not already stored
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 * @param int $ttl Time To Live in seconds. Defaults to 60*60*24
+	 * @return bool
+	 */
+	public function add($key, $value, $ttl = 0) {
+		// since this cache is not shared race conditions aren't an issue
+		if ($this->hasKey($key)) {
+			return false;
+		} else {
+			return $this->set($key, $value, $ttl);
+		}
+	}
+
+	/**
+	 * Increase a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function inc($key, $step = 1) {
+		$oldValue = $this->get($key);
+		if (is_int($oldValue)) {
+			$this->set($key, $oldValue + $step);
+			return $oldValue + $step;
+		} else {
+			$success = $this->add($key, $step);
+			return ($success) ? $step : false;
+		}
+	}
+
+	/**
+	 * Decrease a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function dec($key, $step = 1) {
+		$oldValue = $this->get($key);
+		if (is_int($oldValue)) {
+			$this->set($key, $oldValue - $step);
+			return $oldValue - $step;
+		} else {
+			return false;
+		}
+	}
+
 	/**
 	 * {@inheritDoc}
 	 */
diff --git a/lib/private/memcache/memcached.php b/lib/private/memcache/memcached.php
index a2b3440317f..9566e54c42b 100644
--- a/lib/private/memcache/memcached.php
+++ b/lib/private/memcache/memcached.php
@@ -24,7 +24,9 @@
 
 namespace OC\Memcache;
 
-class Memcached extends Cache {
+use OCP\IMemcache;
+
+class Memcached extends Cache implements IMemcache {
 	/**
 	 * @var \Memcached $cache
 	 */
@@ -100,6 +102,41 @@ class Memcached extends Cache {
 		return true;
 	}
 
+	/**
+	 * Set a value in the cache if it's not already stored
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 * @param int $ttl Time To Live in seconds. Defaults to 60*60*24
+	 * @return bool
+	 */
+	public function add($key, $value, $ttl = 0) {
+		return self::$cache->add($this->getPrefix() . $key, $value, $ttl);
+	}
+
+	/**
+	 * Increase a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function inc($key, $step = 1) {
+		$this->add($key, 0);
+		return self::$cache->increment($this->getPrefix() . $key, $step);
+	}
+
+	/**
+	 * Decrease a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function dec($key, $step = 1) {
+		return self::$cache->decrement($this->getPrefix() . $key, $step);
+	}
+
 	static public function isAvailable() {
 		return extension_loaded('memcached');
 	}
diff --git a/lib/private/memcache/redis.php b/lib/private/memcache/redis.php
index e7425726b2b..dc52c03422a 100644
--- a/lib/private/memcache/redis.php
+++ b/lib/private/memcache/redis.php
@@ -23,7 +23,9 @@
 
 namespace OC\Memcache;
 
-class Redis extends Cache {
+use OCP\IMemcache;
+
+class Redis extends Cache implements IMemcache {
 
 	/**
 	 * @var \Redis $cache
@@ -52,10 +54,10 @@ class Redis extends Cache {
 				$timeout = 0.0; // unlimited
 			}
 
-			self::$cache->connect( $host, $port, $timeout );
+			self::$cache->connect($host, $port, $timeout);
 
 			if (isset($config['dbindex'])) {
-				self::$cache->select( $config['dbindex'] );
+				self::$cache->select($config['dbindex']);
 			}
 		}
 	}
@@ -94,19 +96,59 @@ class Redis extends Cache {
 		} else {
 			return false;
 		}
-
 	}
 
 	public function clear($prefix = '') {
-		$prefix = $this->getNamespace() . $prefix.'*';
+		$prefix = $this->getNamespace() . $prefix . '*';
 		$it = null;
 		self::$cache->setOption(\Redis::OPT_SCAN, \Redis::SCAN_RETRY);
-		while($keys = self::$cache->scan($it, $prefix)) {
+		while ($keys = self::$cache->scan($it, $prefix)) {
 			self::$cache->delete($keys);
 		}
 		return true;
 	}
 
+	/**
+	 * Set a value in the cache if it's not already stored
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 * @param int $ttl Time To Live in seconds. Defaults to 60*60*24
+	 * @return bool
+	 */
+	public function add($key, $value, $ttl = 0) {
+		// dont encode ints for inc/dec
+		if (!is_int($value)) {
+			$value = json_encode($value);
+		}
+		return self::$cache->setnx($this->getPrefix() . $key, $value);
+	}
+
+	/**
+	 * Increase a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function inc($key, $step = 1) {
+		return self::$cache->incrBy($this->getNamespace() . $key, $step);
+	}
+
+	/**
+	 * Decrease a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function dec($key, $step = 1) {
+		if (!$this->hasKey($key)) {
+			return false;
+		}
+		return self::$cache->decrBy($this->getNamespace() . $key, $step);
+	}
+
 	static public function isAvailable() {
 		return extension_loaded('redis');
 	}
diff --git a/lib/private/memcache/xcache.php b/lib/private/memcache/xcache.php
index 33cea23e62b..48b0bd8a289 100644
--- a/lib/private/memcache/xcache.php
+++ b/lib/private/memcache/xcache.php
@@ -24,12 +24,13 @@
  */
 
 namespace OC\Memcache;
+use OCP\IMemcache;
 
 /**
  * See http://xcache.lighttpd.net/wiki/XcacheApi for provided constants and
  * functions etc.
  */
-class XCache extends Cache {
+class XCache extends Cache implements IMemcache {
 	/**
 	 * entries in XCache gets namespaced to prevent collisions between ownCloud instances and users
 	 */
@@ -38,28 +39,28 @@ class XCache extends Cache {
 	}
 
 	public function get($key) {
-		return xcache_get($this->getNamespace().$key);
+		return xcache_get($this->getNamespace() . $key);
 	}
 
-	public function set($key, $value, $ttl=0) {
-		if($ttl>0) {
-			return xcache_set($this->getNamespace().$key, $value, $ttl);
-		}else{
-			return xcache_set($this->getNamespace().$key, $value);
+	public function set($key, $value, $ttl = 0) {
+		if ($ttl > 0) {
+			return xcache_set($this->getNamespace() . $key, $value, $ttl);
+		} else {
+			return xcache_set($this->getNamespace() . $key, $value);
 		}
 	}
 
 	public function hasKey($key) {
-		return xcache_isset($this->getNamespace().$key);
+		return xcache_isset($this->getNamespace() . $key);
 	}
 
 	public function remove($key) {
-		return xcache_unset($this->getNamespace().$key);
+		return xcache_unset($this->getNamespace() . $key);
 	}
 
-	public function clear($prefix='') {
+	public function clear($prefix = '') {
 		if (function_exists('xcache_unset_by_prefix')) {
-			return xcache_unset_by_prefix($this->getNamespace().$prefix);
+			return xcache_unset_by_prefix($this->getNamespace() . $prefix);
 		} else {
 			// Since we can not clear by prefix, we just clear the whole cache.
 			xcache_clear_cache(\XC_TYPE_VAR, 0);
@@ -67,7 +68,46 @@ class XCache extends Cache {
 		return true;
 	}
 
-	static public function isAvailable(){
+	/**
+	 * Set a value in the cache if it's not already stored
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 * @param int $ttl Time To Live in seconds. Defaults to 60*60*24
+	 * @return bool
+	 */
+	public function add($key, $value, $ttl = 0) {
+		if ($this->hasKey($key)) {
+			return false;
+		} else {
+			return $this->set($key, $value, $ttl);
+		}
+	}
+
+	/**
+	 * Increase a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function inc($key, $step = 1) {
+		$this->add($key, 0);
+		return xcache_inc($this->getPrefix() . $key, $step);
+	}
+
+	/**
+	 * Decrease a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 */
+	public function dec($key, $step = 1) {
+		return xcache_dec($this->getPrefix() . $key, $step);
+	}
+
+	static public function isAvailable() {
 		if (!extension_loaded('xcache')) {
 			return false;
 		}
@@ -80,7 +120,7 @@ class XCache extends Cache {
 			// AND administration functions are password-protected.
 			return false;
 		}
-		$var_size = (int) ini_get('xcache.var_size');
+		$var_size = (int)ini_get('xcache.var_size');
 		if (!$var_size) {
 			return false;
 		}
diff --git a/lib/public/imemcache.php b/lib/public/imemcache.php
new file mode 100644
index 00000000000..bc7762f80f9
--- /dev/null
+++ b/lib/public/imemcache.php
@@ -0,0 +1,68 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+/**
+ * Public interface of ownCloud for apps to use.
+ * Cache interface
+ *
+ */
+
+// use OCP namespace for all classes that are considered public.
+// This means that they should be used by apps instead of the internal ownCloud classes
+namespace OCP;
+
+/**
+ * This interface defines method for accessing the file based user cache.
+ *
+ * @since 8.1.0
+ */
+interface IMemcache extends ICache {
+	/**
+	 * Set a value in the cache if it's not already stored
+	 *
+	 * @param string $key
+	 * @param mixed $value
+	 * @param int $ttl Time To Live in seconds. Defaults to 60*60*24
+	 * @return bool
+	 * @since 8.0.0
+	 */
+	public function add($key, $value, $ttl = 0);
+
+	/**
+	 * Increase a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 * @since 8.0.0
+	 */
+	public function inc($key, $step = 1);
+
+	/**
+	 * Decrease a stored number
+	 *
+	 * @param string $key
+	 * @param int $step
+	 * @return int | bool
+	 * @since 8.0.0
+	 */
+	public function dec($key, $step = 1);
+}
diff --git a/tests/lib/memcache/cache.php b/tests/lib/memcache/cache.php
index e5ceae52fb0..80ad182b6bf 100644
--- a/tests/lib/memcache/cache.php
+++ b/tests/lib/memcache/cache.php
@@ -10,6 +10,11 @@
 namespace Test\Memcache;
 
 abstract class Cache extends \Test_Cache {
+	/**
+	 * @var \OCP\IMemcache cache;
+	 */
+	protected $instance;
+
 	public function testExistsAfterSet() {
 		$this->assertFalse($this->instance->hasKey('foo'));
 		$this->instance->set('foo', 'bar');
@@ -56,6 +61,37 @@ abstract class Cache extends \Test_Cache {
 		$this->assertFalse($this->instance->hasKey('foo'));
 	}
 
+	public function testAdd() {
+		$this->assertTrue($this->instance->add('foo', 'bar'));
+		$this->assertEquals('bar', $this->instance->get('foo'));
+		$this->assertFalse($this->instance->add('foo', 'asd'));
+		$this->assertEquals('bar', $this->instance->get('foo'));
+	}
+
+	public function testInc() {
+		$this->assertEquals(1, $this->instance->inc('foo'));
+		$this->assertEquals(1, $this->instance->get('foo'));
+		$this->assertEquals(2, $this->instance->inc('foo'));
+		$this->assertEquals(12, $this->instance->inc('foo', 10));
+
+		$this->instance->set('foo', 'bar');
+		$this->assertFalse($this->instance->inc('foo'));
+		$this->assertEquals('bar', $this->instance->get('foo'));
+	}
+
+	public function testDec() {
+		$this->assertEquals(false, $this->instance->dec('foo'));
+		$this->instance->set('foo', 20);
+		$this->assertEquals(19, $this->instance->dec('foo'));
+		$this->assertEquals(19, $this->instance->get('foo'));
+		$this->assertEquals(9, $this->instance->dec('foo', 10));
+
+		$this->instance->set('foo', 'bar');
+		$this->assertFalse($this->instance->dec('foo'));
+		$this->assertEquals('bar', $this->instance->get('foo'));
+	}
+
+
 	protected function tearDown() {
 		if ($this->instance) {
 			$this->instance->clear();

From acf30ede95f4b8986787f81edcf025a84237b7c5 Mon Sep 17 00:00:00 2001
From: Robin Appelman <icewind@owncloud.com>
Date: Wed, 29 Apr 2015 16:34:36 +0200
Subject: [PATCH 2/6] add compare and swap to memcache

---
 lib/private/memcache/apc.php        | 21 +++++++++++
 lib/private/memcache/arraycache.php | 16 +++++++++
 lib/private/memcache/castrait.php   | 56 +++++++++++++++++++++++++++++
 lib/private/memcache/memcached.php  |  2 ++
 lib/private/memcache/redis.php      |  1 +
 lib/private/memcache/xcache.php     | 28 +++++++++++++--
 lib/public/imemcache.php            | 10 ++++++
 tests/lib/memcache/cache.php        | 12 +++++++
 8 files changed, 144 insertions(+), 2 deletions(-)
 create mode 100644 lib/private/memcache/castrait.php

diff --git a/lib/private/memcache/apc.php b/lib/private/memcache/apc.php
index ba16972e6d6..50b942e7297 100644
--- a/lib/private/memcache/apc.php
+++ b/lib/private/memcache/apc.php
@@ -27,6 +27,10 @@ namespace OC\Memcache;
 use OCP\IMemcache;
 
 class APC extends Cache implements IMemcache {
+	use CASTrait {
+		cas as casEmulated;
+	}
+
 	public function get($key) {
 		$result = apc_fetch($this->getPrefix() . $key, $success);
 		if (!$success) {
@@ -89,6 +93,23 @@ class APC extends Cache implements IMemcache {
 		return apc_dec($this->getPrefix() . $key, $step);
 	}
 
+	/**
+	 * Compare and set
+	 *
+	 * @param string $key
+	 * @param mixed $old
+	 * @param mixed $new
+	 * @return bool
+	 */
+	public function cas($key, $old, $new) {
+		// apc only does cas for ints
+		if (is_int($old) and is_int($new)) {
+			return apc_cas($this->getPrefix() . $key, $old, $new);
+		} else {
+			return $this->casEmulated($key, $old, $new);
+		}
+	}
+
 	static public function isAvailable() {
 		if (!extension_loaded('apc')) {
 			return false;
diff --git a/lib/private/memcache/arraycache.php b/lib/private/memcache/arraycache.php
index 6db920a69a8..2b1b87a9eb3 100644
--- a/lib/private/memcache/arraycache.php
+++ b/lib/private/memcache/arraycache.php
@@ -130,6 +130,22 @@ class ArrayCache extends Cache implements IMemcache {
 		}
 	}
 
+	/**
+	 * Compare and set
+	 *
+	 * @param string $key
+	 * @param mixed $old
+	 * @param mixed $new
+	 * @return bool
+	 */
+	public function cas($key, $old, $new) {
+		if ($this->get($key) === $old) {
+			return $this->set($key, $new);
+		} else {
+			return false;
+		}
+	}
+
 	/**
 	 * {@inheritDoc}
 	 */
diff --git a/lib/private/memcache/castrait.php b/lib/private/memcache/castrait.php
new file mode 100644
index 00000000000..c52538023fb
--- /dev/null
+++ b/lib/private/memcache/castrait.php
@@ -0,0 +1,56 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OC\Memcache;
+
+trait CASTrait {
+	abstract public function get($key);
+
+	abstract public function set($key, $value, $ttl = 0);
+
+	abstract public function remove($key);
+
+	abstract public function add($key, $value, $ttl = 0);
+
+	/**
+	 * Compare and set
+	 *
+	 * @param string $key
+	 * @param mixed $old
+	 * @param mixed $new
+	 * @return bool
+	 */
+	public function cas($key, $old, $new) {
+		//no native cas, emulate with locking
+		if ($this->add($key . '_lock', true)) {
+			if ($this->get($key) === $old) {
+				$this->set($key, $new);
+				$this->remove($key . '_lock');
+				return true;
+			} else {
+				$this->remove($key . '_lock');
+				return false;
+			}
+		} else {
+			return false;
+		}
+	}
+}
diff --git a/lib/private/memcache/memcached.php b/lib/private/memcache/memcached.php
index 9566e54c42b..cf1d651b551 100644
--- a/lib/private/memcache/memcached.php
+++ b/lib/private/memcache/memcached.php
@@ -27,6 +27,8 @@ namespace OC\Memcache;
 use OCP\IMemcache;
 
 class Memcached extends Cache implements IMemcache {
+	use CASTrait;
+
 	/**
 	 * @var \Memcached $cache
 	 */
diff --git a/lib/private/memcache/redis.php b/lib/private/memcache/redis.php
index dc52c03422a..78d061404ef 100644
--- a/lib/private/memcache/redis.php
+++ b/lib/private/memcache/redis.php
@@ -26,6 +26,7 @@ namespace OC\Memcache;
 use OCP\IMemcache;
 
 class Redis extends Cache implements IMemcache {
+	use CASTrait;
 
 	/**
 	 * @var \Redis $cache
diff --git a/lib/private/memcache/xcache.php b/lib/private/memcache/xcache.php
index 48b0bd8a289..3a5bd73d8ad 100644
--- a/lib/private/memcache/xcache.php
+++ b/lib/private/memcache/xcache.php
@@ -24,6 +24,7 @@
  */
 
 namespace OC\Memcache;
+
 use OCP\IMemcache;
 
 /**
@@ -92,7 +93,6 @@ class XCache extends Cache implements IMemcache {
 	 * @return int | bool
 	 */
 	public function inc($key, $step = 1) {
-		$this->add($key, 0);
 		return xcache_inc($this->getPrefix() . $key, $step);
 	}
 
@@ -107,11 +107,35 @@ class XCache extends Cache implements IMemcache {
 		return xcache_dec($this->getPrefix() . $key, $step);
 	}
 
+	/**
+	 * Compare and set
+	 *
+	 * @param string $key
+	 * @param mixed $old
+	 * @param mixed $new
+	 * @return bool
+	 */
+	public function cas($key, $old, $new) {
+		//no native cas, emulate with locking
+		if ($this->add($key . '_lock', true)) {
+			if ($this->get($key) === $old) {
+				$this->set($key, $new);
+				$this->remove($key . '_lock');
+				return true;
+			} else {
+				$this->remove($key . '_lock');
+				return false;
+			}
+		} else {
+			return false;
+		}
+	}
+
 	static public function isAvailable() {
 		if (!extension_loaded('xcache')) {
 			return false;
 		}
-		if (\OC::$CLI) {
+		if (\OC::$CLI && !getenv('XCACHE_TEST')) {
 			return false;
 		}
 		if (!function_exists('xcache_unset_by_prefix') && ini_get('xcache.admin.enable_auth')) {
diff --git a/lib/public/imemcache.php b/lib/public/imemcache.php
index bc7762f80f9..56a33c9572f 100644
--- a/lib/public/imemcache.php
+++ b/lib/public/imemcache.php
@@ -65,4 +65,14 @@ interface IMemcache extends ICache {
 	 * @since 8.0.0
 	 */
 	public function dec($key, $step = 1);
+
+	/**
+	 * Compare and set
+	 *
+	 * @param string $key
+	 * @param mixed $old
+	 * @param mixed $new
+	 * @return bool
+	 */
+	public function cas($key, $old, $new);
 }
diff --git a/tests/lib/memcache/cache.php b/tests/lib/memcache/cache.php
index 80ad182b6bf..9d977cf0247 100644
--- a/tests/lib/memcache/cache.php
+++ b/tests/lib/memcache/cache.php
@@ -91,6 +91,18 @@ abstract class Cache extends \Test_Cache {
 		$this->assertEquals('bar', $this->instance->get('foo'));
 	}
 
+	public function testCasNotChanged() {
+		$this->instance->set('foo', 'bar');
+		$this->assertTrue($this->instance->cas('foo', 'bar', 'asd'));
+		$this->assertEquals('asd', $this->instance->get('foo'));
+	}
+
+	public function testCasChanged() {
+		$this->instance->set('foo', 'bar1');
+		$this->assertFalse($this->instance->cas('foo', 'bar', 'asd'));
+		$this->assertEquals('bar1', $this->instance->get('foo'));
+	}
+
 
 	protected function tearDown() {
 		if ($this->instance) {

From 96f9573a4b0addc4b0fad6a6ac2faef8da187aff Mon Sep 17 00:00:00 2001
From: Robin Appelman <icewind@owncloud.com>
Date: Wed, 29 Apr 2015 17:19:02 +0200
Subject: [PATCH 3/6] add memcache based shared/exclusive locking

---
 lib/private/lock/memcachelockingprovider.php |  86 ++++++++++++++
 lib/public/lock/ilockingprovider.php         |  47 ++++++++
 lib/public/lock/lockedexception.php          |  25 ++++
 tests/lib/lock/lockingprovider.php           | 118 +++++++++++++++++++
 tests/lib/lock/memcachelockingprovider.php   |  45 +++++++
 5 files changed, 321 insertions(+)
 create mode 100644 lib/private/lock/memcachelockingprovider.php
 create mode 100644 lib/public/lock/ilockingprovider.php
 create mode 100644 lib/public/lock/lockedexception.php
 create mode 100644 tests/lib/lock/lockingprovider.php
 create mode 100644 tests/lib/lock/memcachelockingprovider.php

diff --git a/lib/private/lock/memcachelockingprovider.php b/lib/private/lock/memcachelockingprovider.php
new file mode 100644
index 00000000000..43fdf70bc8b
--- /dev/null
+++ b/lib/private/lock/memcachelockingprovider.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OC\Lock;
+
+use OCP\Lock\ILockingProvider;
+use OCP\Lock\LockedException;
+use OCP\IMemcache;
+
+class MemcacheLockingProvider implements ILockingProvider {
+	/**
+	 * @var \OCP\IMemcache
+	 */
+	private $memcache;
+
+	/**
+	 * @param \OCP\IMemcache $memcache
+	 */
+	public function __construct(IMemcache $memcache) {
+		$this->memcache = $memcache;
+	}
+
+	/**
+	 * @param string $path
+	 * @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
+	 * @return bool
+	 */
+	public function isLocked($path, $type) {
+		$lockValue = $this->memcache->get($path);
+		if ($type === self::LOCK_SHARED) {
+			return $lockValue > 0;
+		} else if ($type === self::LOCK_EXCLUSIVE) {
+			return $lockValue === 'exclusive';
+		} else {
+			return false;
+		}
+	}
+
+	/**
+	 * @param string $path
+	 * @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
+	 * @throws \OCP\Lock\LockedException
+	 */
+	public function acquireLock($path, $type) {
+		if ($type === self::LOCK_SHARED) {
+			if (!$this->memcache->inc($path)) {
+				throw new LockedException($path . ' is locked');
+			}
+		} else {
+			$this->memcache->add($path, 0);
+			if (!$this->memcache->cas($path, 0, 'exclusive')) {
+				throw new LockedException($path . ' is locked');
+			}
+		}
+	}
+
+	/**
+	 * @param string $path
+	 * @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
+	 */
+	public function releaseLock($path, $type) {
+		if ($type === self::LOCK_SHARED) {
+			$this->memcache->dec($path);
+		} else if ($type === self::LOCK_EXCLUSIVE) {
+			$this->memcache->cas($path, 'exclusive', 0);
+		}
+	}
+}
diff --git a/lib/public/lock/ilockingprovider.php b/lib/public/lock/ilockingprovider.php
new file mode 100644
index 00000000000..a584ec02ef6
--- /dev/null
+++ b/lib/public/lock/ilockingprovider.php
@@ -0,0 +1,47 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\Lock;
+
+interface ILockingProvider {
+	const LOCK_SHARED = 1;
+	const LOCK_EXCLUSIVE = 2;
+
+	/**
+	 * @param string $path
+	 * @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
+	 * @return bool
+	 */
+	public function isLocked($path, $type);
+
+	/**
+	 * @param string $path
+	 * @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
+	 * @throws \OCP\Files\Lock\LockedException
+	 */
+	public function acquireLock($path, $type);
+
+	/**
+	 * @param string $path
+	 * @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
+	 */
+	public function releaseLock($path, $type);
+}
diff --git a/lib/public/lock/lockedexception.php b/lib/public/lock/lockedexception.php
new file mode 100644
index 00000000000..4c0ca9b8c5b
--- /dev/null
+++ b/lib/public/lock/lockedexception.php
@@ -0,0 +1,25 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\Lock;
+
+class LockedException extends \Exception {
+}
diff --git a/tests/lib/lock/lockingprovider.php b/tests/lib/lock/lockingprovider.php
new file mode 100644
index 00000000000..e7b8028dc94
--- /dev/null
+++ b/tests/lib/lock/lockingprovider.php
@@ -0,0 +1,118 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Lock;
+
+use OCP\Lock\ILockingProvider;
+use Test\TestCase;
+
+abstract class LockingProvider extends TestCase {
+	/**
+	 * @var \OCP\Lock\ILockingProvider
+	 */
+	protected $instance;
+
+	/**
+	 * @return \OCP\Lock\ILockingProvider
+	 */
+	abstract protected function getInstance();
+
+	protected function setUp() {
+		parent::setUp();
+		$this->instance = $this->getInstance();
+	}
+
+	public function testExclusiveLock() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->assertFalse($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+	}
+
+	public function testSharedLock() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertFalse($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+	}
+
+	public function testDoubleSharedLock() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertFalse($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+	}
+
+	public function testReleaseSharedLock() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertFalse($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+		$this->instance->releaseLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+		$this->instance->releaseLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertFalse($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+	}
+
+	/**
+	 * @expectedException \OCP\Lock\LockedException
+	 */
+	public function testDoubleExclusiveLock() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+	}
+
+	public function testReleaseExclusiveLock() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->instance->releaseLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+		$this->assertFalse($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+	}
+
+	/**
+	 * @expectedException \OCP\Lock\LockedException
+	 */
+	public function testExclusiveLockAfterShared() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+	}
+
+	public function testExclusiveLockAfterSharedReleased() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_SHARED));
+		$this->instance->releaseLock('foo', ILockingProvider::LOCK_SHARED);
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+	}
+
+
+	/**
+	 * @expectedException \OCP\Lock\LockedException
+	 */
+	public function testSharedLockAfterExclusive() {
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
+		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
+		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
+	}
+}
diff --git a/tests/lib/lock/memcachelockingprovider.php b/tests/lib/lock/memcachelockingprovider.php
new file mode 100644
index 00000000000..40478b22939
--- /dev/null
+++ b/tests/lib/lock/memcachelockingprovider.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Lock;
+
+use OC\Memcache\ArrayCache;
+
+class MemcacheLockingProvider extends LockingProvider {
+
+	/**
+	 * @var \OCP\IMemcache
+	 */
+	private $memcache;
+
+	/**
+	 * @return \OCP\Lock\ILockingProvider
+	 */
+	protected function getInstance() {
+		$this->memcache = new ArrayCache();
+		return new \OC\Lock\MemcacheLockingProvider($this->memcache);
+	}
+
+	public function tearDown() {
+		$this->memcache->clear();
+		parent::tearDown();
+	}
+}

From a40a237441670a4c575a224158b4a2a7c2fb5266 Mon Sep 17 00:00:00 2001
From: Robin Appelman <icewind@owncloud.com>
Date: Thu, 30 Apr 2015 13:39:31 +0200
Subject: [PATCH 4/6] use trait for cas polyfill for xcache

---
 lib/private/memcache/xcache.php | 26 ++------------------------
 1 file changed, 2 insertions(+), 24 deletions(-)

diff --git a/lib/private/memcache/xcache.php b/lib/private/memcache/xcache.php
index 3a5bd73d8ad..0be79d06ed9 100644
--- a/lib/private/memcache/xcache.php
+++ b/lib/private/memcache/xcache.php
@@ -32,6 +32,8 @@ use OCP\IMemcache;
  * functions etc.
  */
 class XCache extends Cache implements IMemcache {
+	use CASTrait;
+
 	/**
 	 * entries in XCache gets namespaced to prevent collisions between ownCloud instances and users
 	 */
@@ -107,30 +109,6 @@ class XCache extends Cache implements IMemcache {
 		return xcache_dec($this->getPrefix() . $key, $step);
 	}
 
-	/**
-	 * Compare and set
-	 *
-	 * @param string $key
-	 * @param mixed $old
-	 * @param mixed $new
-	 * @return bool
-	 */
-	public function cas($key, $old, $new) {
-		//no native cas, emulate with locking
-		if ($this->add($key . '_lock', true)) {
-			if ($this->get($key) === $old) {
-				$this->set($key, $new);
-				$this->remove($key . '_lock');
-				return true;
-			} else {
-				$this->remove($key . '_lock');
-				return false;
-			}
-		} else {
-			return false;
-		}
-	}
-
 	static public function isAvailable() {
 		if (!extension_loaded('xcache')) {
 			return false;

From 8119b8b0403b83970f329a8512de980580b013d6 Mon Sep 17 00:00:00 2001
From: Robin Appelman <icewind@owncloud.com>
Date: Thu, 30 Apr 2015 14:05:05 +0200
Subject: [PATCH 5/6] add tests for castrait

---
 tests/lib/memcache/castrait.php | 73 +++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 tests/lib/memcache/castrait.php

diff --git a/tests/lib/memcache/castrait.php b/tests/lib/memcache/castrait.php
new file mode 100644
index 00000000000..17f412bb638
--- /dev/null
+++ b/tests/lib/memcache/castrait.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Memcache;
+
+use Test\TestCase;
+
+class CasTrait extends TestCase {
+	/**
+	 * @return \OC\Memcache\CasTrait
+	 */
+	private function getCache() {
+		$sourceCache = new \OC\Memcache\ArrayCache();
+		$mock = $this->getMockForTrait('\OC\Memcache\CasTrait');
+
+		$mock->expects($this->any())
+			->method('set')
+			->will($this->returnCallback(function ($key, $value, $ttl) use ($sourceCache) {
+				return $sourceCache->set($key, $value, $ttl);
+			}));
+
+		$mock->expects($this->any())
+			->method('get')
+			->will($this->returnCallback(function ($key) use ($sourceCache) {
+				return $sourceCache->get($key);
+			}));
+
+		$mock->expects($this->any())
+			->method('add')
+			->will($this->returnCallback(function ($key, $value, $ttl) use ($sourceCache) {
+				return $sourceCache->add($key, $value, $ttl);
+			}));
+
+		$mock->expects($this->any())
+			->method('remove')
+			->will($this->returnCallback(function ($key) use ($sourceCache) {
+				return $sourceCache->remove($key);
+			}));
+		return $mock;
+	}
+
+	public function testCasNotChanged() {
+		$cache = $this->getCache();
+		$cache->set('foo', 'bar');
+		$this->assertTrue($cache->cas('foo', 'bar', 'asd'));
+		$this->assertEquals('asd', $cache->get('foo'));
+	}
+
+	public function testCasChanged() {
+		$cache = $this->getCache();
+		$cache->set('foo', 'bar1');
+		$this->assertFalse($cache->cas('foo', 'bar', 'asd'));
+		$this->assertEquals('bar1', $cache->get('foo'));
+	}
+}

From ba7d221cffab4b42871e5926dd6c3e0a2d2b98dc Mon Sep 17 00:00:00 2001
From: Robin Appelman <icewind@owncloud.com>
Date: Thu, 30 Apr 2015 14:16:09 +0200
Subject: [PATCH 6/6] allow getting the path from the lockedexception

---
 lib/private/lock/memcachelockingprovider.php |  4 ++--
 lib/public/lock/lockedexception.php          | 21 ++++++++++++++++++++
 tests/lib/lock/lockingprovider.php           | 19 ++++++++++++++++++
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/lib/private/lock/memcachelockingprovider.php b/lib/private/lock/memcachelockingprovider.php
index 43fdf70bc8b..9c8c7235462 100644
--- a/lib/private/lock/memcachelockingprovider.php
+++ b/lib/private/lock/memcachelockingprovider.php
@@ -62,12 +62,12 @@ class MemcacheLockingProvider implements ILockingProvider {
 	public function acquireLock($path, $type) {
 		if ($type === self::LOCK_SHARED) {
 			if (!$this->memcache->inc($path)) {
-				throw new LockedException($path . ' is locked');
+				throw new LockedException($path);
 			}
 		} else {
 			$this->memcache->add($path, 0);
 			if (!$this->memcache->cas($path, 0, 'exclusive')) {
-				throw new LockedException($path . ' is locked');
+				throw new LockedException($path);
 			}
 		}
 	}
diff --git a/lib/public/lock/lockedexception.php b/lib/public/lock/lockedexception.php
index 4c0ca9b8c5b..87f7164b7e0 100644
--- a/lib/public/lock/lockedexception.php
+++ b/lib/public/lock/lockedexception.php
@@ -22,4 +22,25 @@
 namespace OCP\Lock;
 
 class LockedException extends \Exception {
+	/**
+	 * @var string
+	 */
+	private $path;
+
+	/**
+	 * LockedException constructor.
+	 *
+	 * @param string $path
+	 */
+	public function __construct($path) {
+		parent::__construct($path . ' is locked');
+		$this->path = $path;
+	}
+
+	/**
+	 * @return string
+	 */
+	public function getPath() {
+		return $this->path;
+	}
 }
diff --git a/tests/lib/lock/lockingprovider.php b/tests/lib/lock/lockingprovider.php
index e7b8028dc94..08d879da8bb 100644
--- a/tests/lib/lock/lockingprovider.php
+++ b/tests/lib/lock/lockingprovider.php
@@ -22,6 +22,7 @@
 namespace Test\Lock;
 
 use OCP\Lock\ILockingProvider;
+use OCP\Lock\LockedException;
 use Test\TestCase;
 
 abstract class LockingProvider extends TestCase {
@@ -115,4 +116,22 @@ abstract class LockingProvider extends TestCase {
 		$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
 		$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
 	}
+
+	public function testLockedExceptionHasPathForShared() {
+		try {
+			$this->testSharedLockAfterExclusive();
+			$this->fail('Expected locked exception');
+		} catch (LockedException $e) {
+			$this->assertEquals('foo', $e->getPath());
+		}
+	}
+
+	public function testLockedExceptionHasPathForExclusive() {
+		try {
+			$this->testExclusiveLockAfterShared();
+			$this->fail('Expected locked exception');
+		} catch (LockedException $e) {
+			$this->assertEquals('foo', $e->getPath());
+		}
+	}
 }