Common application concurrency Lock for PHP redis. (Pessimistic Lock)

Redis implements pessimistic locks.

Principle, in the grab lock, Rob failed to wait a second to rob, and then another second to rob, so repeated circulation.

Unlocking means deleting the corresponding key.

/** * Realize Redis pessimistic lock * User:babytuo*/ClassRedislock { Public $expire= 2;  Public functionTest () {$this->lock ("Test1"); Echo"111"; }     Public functionLock$key){        $redis= Self::createredisobj (); $now= Time(); /** Understanding SETNX if a given key already exists, then SETNX does not do any action.         Setnx is a shorthand for "set if not EXists" (set if it does not exist). */        //grab the lock.        $isLock=$redis->SETNX ($key, Time() +$this->expire);//set to the expiration time. Not successful         while( !$isLock) {            $now++; $time=$now+$this-expire; //and re-create            $lock=$redis->SETNX ($key,$time); if($lock= = 1 | | ($now>$redis->get ($key) &&$now>$redis->getset ($key,$time))) {//after the lock is successful, set a new expiration time.                 Break; } Else {                Sleep(1);//0.5s            }        }        return true; }    /** * unlock * @param type $flag * @return Boolean*/     Public functionUnlock$key) {        $redis= Self::createredisobj (); $redis->del ($key); return true; }    /** * Check if the lock exists * @param $key * @return bool*/     Public functionChecklock ($key){        $redis= Self::createredisobj (); return $redis->exists ($key); }     Public Static $_redis; /** * Create a Redis object. * @return Redis*/     Public Static functioncreateredisobj () {if(! Self::$_redis){            $redis=NewRedis (); $info= Yii::app ()->cache->servers[0];//Read Configuration            $host=$info["Host"]; $port=$info["Port"]; $redis->connect ($host,$port); $redis _db= Yii::app ()->settings->get (' System ', ' redis_db ');//Set the default library            $redis->select ($redis _db); Self::$_redis=$redis; }        returnSelf::$_redis; }}

Common application concurrency Lock for PHP redis. (Pessimistic Lock)