<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\caching;

/**
 * XCache provides XCache caching in terms of an application component.
 *
 * To use this application component, the [XCache PHP extension](http://xcache.lighttpd.net/) must be loaded.
 * Also note that the [[flush()]] functionality will work correctly only if "xcache.admin.enable_auth"
 * is set to "Off" in php.ini.
 *
 * See [[Cache]] for common cache operations that XCache supports.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class XCache extends Cache
{
	/**
	 * Retrieves a value from cache with a specified key.
	 * This is the implementation of the method declared in the parent class.
	 * @param string $key a unique key identifying the cached value
	 * @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
	 */
	protected function getValue($key)
	{
		return xcache_isset($key) ? xcache_get($key) : false;
	}

	/**
	 * Stores a value identified by a key in cache.
	 * This is the implementation of the method declared in the parent class.
	 *
	 * @param string $key the key identifying the value to be cached
	 * @param string $value the value to be cached
	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
	 * @return boolean true if the value is successfully stored into cache, false otherwise
	 */
	protected function setValue($key, $value, $expire)
	{
		return xcache_set($key, $value, $expire);
	}

	/**
	 * Stores a value identified by a key into cache if the cache does not contain this key.
	 * This is the implementation of the method declared in the parent class.
	 *
	 * @param string $key the key identifying the value to be cached
	 * @param string $value the value to be cached
	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
	 * @return boolean true if the value is successfully stored into cache, false otherwise
	 */
	protected function addValue($key, $value, $expire)
	{
		return !xcache_isset($key) ? $this->setValue($key, $value, $expire) : false;
	}

	/**
	 * Deletes a value with the specified key from cache
	 * This is the implementation of the method declared in the parent class.
	 * @param string $key the key of the value to be deleted
	 * @return boolean if no error happens during deletion
	 */
	protected function deleteValue($key)
	{
		return xcache_unset($key);
	}

	/**
	 * Deletes all values from cache.
	 * This is the implementation of the method declared in the parent class.
	 * @return boolean whether the flush operation was successful.
	 */
	protected function flushValues()
	{
		for ($i = 0, $max = xcache_count(XC_TYPE_VAR); $i < $max; $i++) {
			if (xcache_clear_cache(XC_TYPE_VAR, $i) === false) {
				return false;
			}
		}
		return true;
	}
}