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<?php
/**
* @copyright Copyright (c) 2016, ownCloud, Inc.
*
* @author Robin Appelman <robin@icewind.nl>
*
* @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
* @template T
*/
class CappedMemoryCache implements ICache, \ArrayAccess {
private $capacity;
/** @var T[] */
private $cache = [];
public function __construct($capacity = 512) {
$this->capacity = $capacity;
}
public function hasKey($key): bool {
return isset($this->cache[$key]);
}
/**
* @return ?T
*/
public function get($key) {
return $this->cache[$key] ?? null;
}
/**
* @param string $key
* @param T $value
* @param int $ttl
* @return bool
*/
public function set($key, $value, $ttl = 0): bool {
if (is_null($key)) {
$this->cache[] = $value;
} else {
$this->cache[$key] = $value;
}
$this->garbageCollect();
return true;
}
public function remove($key) {
unset($this->cache[$key]);
return true;
}
public function clear($prefix = '') {
$this->cache = [];
return true;
}
public function offsetExists($offset): bool {
return $this->hasKey($offset);
}
/**
* @return T
*/
#[\ReturnTypeWillChange]
public function &offsetGet($offset) {
return $this->cache[$offset];
}
/**
* @param string $key
* @param T $value
* @return void
*/
public function offsetSet($offset, $value): void {
$this->set($offset, $value);
}
public function offsetUnset($offset): void {
$this->remove($offset);
}
/**
* @return T[]
*/
public function getData() {
return $this->cache;
}
private function garbageCollect() {
while (count($this->cache) > $this->capacity) {
reset($this->cache);
$key = key($this->cache);
$this->remove($key);
}
}
}
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