ssdb的Yiicache扩展

google的leveldb越来越被很多人接受。国内的ideawu基于leveldb还写了一个ssdb的前置扩展用来实现了很多功能，比如标准的getset和hget,hset还有zset,zget，也实现了队列。当然pub/sub就没有办法实现了。毕竟它和redis还是有点区别。 基于标准的ssdb的类，写了

google的leveldb越来越被很多人接受。国内的ideawu基于leveldb还写了一个ssdb的前置扩展用来实现了很多功能，比如标准的getset和hget,hset还有zset,zget，也实现了队列。当然pub/sub就没有办法实现了。毕竟它和redis还是有点区别。

基于标准的ssdb的类，写了个小扩展，扩展了Yii的Cache类：

    class?CSsdbCache?extends?CCache??
    {??
    ????/**?
    ?????*?@var?string?hostname?to?use?for?connecting?to?the?redis?server.?Defaults?to?'127.0.0.1'.?
    ?????*/??
    ????public?$hostname?=?'127.0.0.1';??
    ????/**?
    ?????*?@var?int?the?port?to?use?for?connecting?to?the?ssdb?server.?Default?port?is?8888.?
    ?????*/??
    ????public?$port?=?8888;??
    ????/**?
    ?????*?@var?float?
    ?????*/??
    ????public?$timeout?=?2000;??
    ????public?$serializer?=?false;??
    ????public?$_cache;??
    ????protected?$_cachekeys?=?'ssdb_cachekey';??
    ??????
    ????public?function?init()?{??
    ????????parent::init();??
    ????}??
    ????/**?
    ?????*?@return?SSDB?
    ?????*/??
    ????public?function?getSsdbCache()?{??
    ????????if?($this->_cache?!==?null)??
    ????????????return?$this->_cache;??
    ????????else?{??
    ????????????return?$this->_cache?=?new?SimpleSSDB($this->hostname,?$this->port,?$this->timeout);??
    ????????}??
    ????}??
    ????public?function?getkeys()?{??
    ????????return?$this->getSsdbCache()->hkeys($this->_cachekeys,?"",?"",?$this->getSsdbCache()->hsize($this->_cachekeys));??
    ????}??
    ????/**?
    ?????*?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?unserialize($this->getSsdbCache()->get($key));??
    ????}??
    ??
    ????/**?
    ?????*?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)?{??
    ????????$this->getSsdbCache()->hset($this->_cachekeys,?$key,?1);??
    ????????if?($expire?>?0)?{??
    ????????????//$expire?+=?time();??
    ????????????return?$this->getSsdbCache()->setx($key,?serialize($value),?(int)?$expire);??
    ????????}??
    ????????else?{??
    ????????????return?$this->getSsdbCache()->set($key,?serialize($value));??
    ????????}??
    ????}??
    ????/**?
    ?????*?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?$this->setValue($key,?$value,?$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)?{??
    ????????$this->getSsdbCache()->hdel($this->_cachekeys,?$key);??
    ????????return?$this->getSsdbCache()->del($key);??
    ????}??
    ????/**?
    ?????*?@return?boolean?whether?the?flush?operation?was?successful.?
    ?????*/??
    ????protected?function?flushValues()?{??
    ????????$this->getSsdbCache()->multi_del($this->getkeys());??
    ????????return?$this->getSsdbCache()->hclear($this->_cachekeys);??
    ????}??
    }??

其实代码很简单，不过由于ssdb默认没有serialize功能，所以在存储之前，得先主动的serialize，然后get的时候unserialize。不然就没有办法存储数组了。

由于ssdb没有flush功能。所以利用hget/hset将所有的key存储下来。flush的时候把hget获取的key读出来删除。然后再清掉这个hget的key

最后还有expire。ssdb里的setx第三个参数。。。居然不是expire，而是ttl。开始的时候，一直都当成expire。结果浪费了很长时间

原文地址：ssdb的Yii cache扩展, 感谢原作者分享。