防缓存失效惊群

[guanhui07]

大并发下 防缓存失效惊群

public function setByLock($key, $value, $ttl = null,$redis)
    {
        if (is_numeric($ttl) && intval($ttl) > 0) {
            $ttl = intval($ttl);
            $exp = time() + $ttl;
            $arg = array("data" => $value, "expire" => $exp);
        } else {
            $ttl = 30;//300
            $exp = time() + $ttl;
        }
        empty($ttl) OR $ttl += 30; //300增加redis缓存时间，使程序有足够的时间生成缓存
        $arg = array("data" => $value, "expire" => $exp);
        $rs = $redis->setex($key, $ttl, json_encode($arg, TRUE));
        $redis->del($key . ".lock");
        return $rs;
    }   

    public function getByLock($key,$redis)
    {
        $sth = $redis->get($key);
        if ($sth === false) {
            return $sth;
        } else {
            $sth = json_decode($sth, TRUE);
            if (intval($sth['expire']) <= time()) {
                $lock = $redis->incr($key . ".lock");
                if ($lock === 1) {
                    return false;
                } else {
                    return $sth['data'];
                }
            } else {
                return $sth['data'];
            }
        }
    }