php中使用redis实现秒杀

<?php
/**
 * $productTotal 商品总数
 * $productSellNum 已售商品数量
 * $currentBuyNum 当前购买数量
 */

//商品总数
$productTotal = 100;

//当前购买数量
$currentBuyNum = 5;

try {
    $redis = new redis();
    $result = $redis->connect('127.0.0.1',6379);
    if(!$result){
        throw new Exception('redis连接失败');
    }
} catch (Exception $e){
    echo $e->getMessage();
    die;
}

//监视 product_sell_num
$redis->watch('product_sell_num');
//已售商品数量
$productSellNum = $redis->get('product_sell_num');
//判断商品是否剩余
if($productSellNum + $currentBuyNum <= $productTotal){
    $redis->multi();
    $redis->set('product_sell_num',$productSellNum + $currentBuyNum);
    $status = $redis->exec();
    if($status){
        //对购买信息处理
    }else{
        return "抢购失败";
    }
}else{
    return "抢购结束";
}