1 files changed, 87 insertions, 0 deletions
diff --git a/lib/private/Cache/CappedMemoryCache.php b/lib/private/Cache/CappedMemoryCache.php
new file mode 100644
index 00000000000..e3efbf76a23
--- /dev/null
+++ b/lib/private/Cache/CappedMemoryCache.php
@@ -0,0 +1,87 @@
+<?php
+/**
+ * @author Robin Appelman <icewind@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, 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\Cache;
+
+use OCP\ICache;
+
+/**
+ * In-memory cache with a capacity limit to keep memory usage in check
+ *
+ * Uses a simple FIFO expiry mechanism
+ */
+class CappedMemoryCache implements ICache, \ArrayAccess {
+
+	private $capacity;
+	private $cache = [];
+
+	public function __construct($capacity = 512) {
+		$this->capacity = $capacity;
+	}
+
+	public function hasKey($key) {
+		return isset($this->cache[$key]);
+	}
+
+	public function get($key) {
+		return isset($this->cache[$key]) ? $this->cache[$key] : null;
+	}
+
+	public function set($key, $value, $ttl = 0) {
+		$this->cache[$key] = $value;
+		$this->garbageCollect();
+	}
+
+	public function remove($key) {
+		unset($this->cache[$key]);
+		return true;
+	}
+
+	public function clear($prefix = '') {
+		$this->cache = [];
+		return true;
+	}
+
+	public function offsetExists($offset) {
+		return $this->hasKey($offset);
+	}
+
+	public function &offsetGet($offset) {
+		return $this->cache[$offset];
+	}
+
+	public function offsetSet($offset, $value) {
+		$this->set($offset, $value);
+	}
+
+	public function offsetUnset($offset) {
+		$this->remove($offset);
+	}
+
+
+	private function garbageCollect() {
+		while (count($this->cache) > $this->capacity) {
+			reset($this->cache);
+			$key = key($this->cache);
+			$this->remove($key);
+		}
+	}
+}