Redis classic case sharing product flash sale and shopping cart

<?php  
    header("content-type:text/html;charset=utf-8");  
    $redis = new redis();  
    $result = $redis->connect('10.10.10.119', 6379);  
    $mywatchkey = $redis->get("mywatchkey");  
    $rob_total = 100;   //抢购数量  
    if($mywatchkey<$rob_total){  
        $redis->watch("mywatchkey");  
        $redis->multi();  
        //设置延迟，方便测试效果。  
        sleep(5);  
        //插入抢购数据  
        $redis->hSet("mywatchlist","user_id_".mt_rand(1, 9999),time());  
        $redis->set("mywatchkey",$mywatchkey+1);  
        $rob_result = $redis->exec();  
        if($rob_result){  
            $mywatchlist = $redis->hGetAll("mywatchlist");  
            echo "抢购成功！<br/>";  
            echo "剩余数量：".($rob_total-$mywatchkey-1)."<br/>";  
            echo "用户列表：<pre class="brush:php;toolbar:false">";  
            var_dump($mywatchlist);  
        }else{  
            echo "手气不好，再抢购！";exit;  
        }  
    }