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

namespace yii\caching;

use yii\base\InvalidConfigException;

/**
 * MemCache implements a cache application component based on [memcache](http://pecl.php.net/package/memcache)
 * and [memcached](http://pecl.php.net/package/memcached).
 *
 * MemCache supports both [memcache](http://pecl.php.net/package/memcache) and
 * [memcached](http://pecl.php.net/package/memcached). By setting [[useMemcached]] to be true or false,
 * one can let MemCache to use either memcached or memcache, respectively.
 *
 * MemCache can be configured with a list of memcache servers by settings its [[servers]] property.
 * By default, MemCache assumes there is a memcache server running on localhost at port 11211.
 *
 * See [[Cache]] for common cache operations that MemCache supports.
 *
 * Note, there is no security measure to protected data in memcache.
 * All data in memcache can be accessed by any process running in the system.
 *
 * To use MemCache as the cache application component, configure the application as follows,
 *
 * ~~~
 * [
 *     'components' => [
 *         'cache' => [
 *             'class' => 'yii\caching\MemCache',
 *             'servers' => [
 *                 [
 *                     'host' => 'server1',
 *                     'port' => 11211,
 *                     'weight' => 60,
 *                 ],
 *                 [
 *                     'host' => 'server2',
 *                     'port' => 11211,
 *                     'weight' => 40,
 *                 ],
 *             ],
 *         ],
 *     ],
 * ]
 * ~~~
 *
 * In the above, two memcache servers are used: server1 and server2. You can configure more properties of
 * each server, such as `persistent`, `weight`, `timeout`. Please see [[MemCacheServer]] for available options.
 *
 * @property \Memcache|\Memcached $memcache The memcache (or memcached) object used by this cache component.
 * This property is read-only.
 * @property MemCacheServer[] $servers List of memcache server configurations. Note that the type of this
 * property differs in getter and setter. See [[getServers()]] and [[setServers()]] for details.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class MemCache extends Cache
{
    /**
     * @var boolean whether to use memcached or memcache as the underlying caching extension.
     * If true, [memcached](http://pecl.php.net/package/memcached) will be used.
     * If false, [memcache](http://pecl.php.net/package/memcache) will be used.
     * Defaults to false.
     */
    public $useMemcached = false;
    /**
     * @var \Memcache|\Memcached the Memcache instance
     */
    private $_cache = null;
    /**
     * @var array list of memcache server configurations
     */
    private $_servers = [];


    /**
     * Initializes this application component.
     * It creates the memcache instance and adds memcache servers.
     */
    public function init()
    {
        parent::init();
        $servers = $this->getServers();
        $cache = $this->getMemCache();
        if (empty($servers)) {
            $cache->addServer('127.0.0.1', 11211);
        } else {
            if (!$this->useMemcached) {
                // different version of memcache may have different number of parameters for the addServer method.
                $class = new \ReflectionClass($cache);
                $paramCount = $class->getMethod('addServer')->getNumberOfParameters();
            }
            foreach ($servers as $server) {
                if ($server->host === null) {
                    throw new InvalidConfigException("The 'host' property must be specified for every memcache server.");
                }
                if ($this->useMemcached) {
                    $cache->addServer($server->host, $server->port, $server->weight);
                } else {
                    // $timeout is used for memcache versions that do not have timeoutms parameter
                    $timeout = (int) ($server->timeout / 1000) + (($server->timeout % 1000 > 0) ? 1 : 0);
                    if ($paramCount === 9) {
                        $cache->addServer(
                            $server->host, $server->port, $server->persistent,
                            $server->weight, $timeout, $server->retryInterval,
                            $server->status, $server->failureCallback, $server->timeout
                        );
                    } else {
                        $cache->addServer(
                            $server->host, $server->port, $server->persistent,
                            $server->weight, $timeout, $server->retryInterval,
                            $server->status, $server->failureCallback
                        );
                    }
                }
            }
        }
    }

    /**
     * Returns the underlying memcache (or memcached) object.
     * @return \Memcache|\Memcached the memcache (or memcached) object used by this cache component.
     * @throws InvalidConfigException if memcache or memcached extension is not loaded
     */
    public function getMemcache()
    {
        if ($this->_cache === null) {
            $extension = $this->useMemcached ? 'memcached' : 'memcache';
            if (!extension_loaded($extension)) {
                throw new InvalidConfigException("MemCache requires PHP $extension extension to be loaded.");
            }
            $this->_cache = $this->useMemcached ? new \Memcached : new \Memcache;
        }

        return $this->_cache;
    }

    /**
     * Returns the memcache server configurations.
     * @return MemCacheServer[] list of memcache server configurations.
     */
    public function getServers()
    {
        return $this->_servers;
    }

    /**
     * @param array $config list of memcache server configurations. Each element must be an array
     * with the following keys: host, port, persistent, weight, timeout, retryInterval, status.
     * @see http://www.php.net/manual/en/function.Memcache-addServer.php
     */
    public function setServers($config)
    {
        foreach ($config as $c) {
            $this->_servers[] = new MemCacheServer($c);
        }
    }

    /**
     * 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 $this->_cache->get($key);
    }

    /**
     * Retrieves multiple values from cache with the specified keys.
     * @param array $keys a list of keys identifying the cached values
     * @return array a list of cached values indexed by the keys
     */
    protected function getValues($keys)
    {
        return $this->useMemcached ? $this->_cache->getMulti($keys) : $this->_cache->get($keys);
    }

    /**
     * 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 $duration the number of seconds in which the cached value will expire. 0 means never expire.
     * @return boolean true if the value is successfully stored into cache, false otherwise
     */
    protected function setValue($key, $value, $duration)
    {
        $expire = $duration > 0 ? $duration + time() : 0;

        return $this->useMemcached ? $this->_cache->set($key, $value, $expire) : $this->_cache->set($key, $value, 0, $expire);
    }

    /**
     * Stores multiple key-value pairs in cache.
     * @param array $data array where key corresponds to cache key while value is the value stored
     * @param integer $duration the number of seconds in which the cached values will expire. 0 means never expire.
     * @return array array of failed keys. Always empty in case of using memcached.
     */
    protected function setValues($data, $duration)
    {
        if ($this->useMemcached) {
            $this->_cache->setMulti($data, $duration > 0 ? $duration + time() : 0);

            return [];
        } else {
            return parent::setValues($data, $duration);
        }
    }

    /**
     * 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 $duration the number of seconds in which the cached value will expire. 0 means never expire.
     * @return boolean true if the value is successfully stored into cache, false otherwise
     */
    protected function addValue($key, $value, $duration)
    {
        $expire = $duration > 0 ? $duration + time() : 0;

        return $this->useMemcached ? $this->_cache->add($key, $value, $expire) : $this->_cache->add($key, $value, 0, $expire);
    }

    /**
     * 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 $this->_cache->delete($key, 0);
    }

    /**
     * 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()
    {
        return $this->_cache->flush();
    }
}
