php和redis实现秒杀活动的流程

日期：2020-05-21 栏目：程序人生浏览：次

1 说明

前段时间面试的时候，一直被问到如何设计一个秒杀活动，但是无奈没有此方面的实际经验，所以只好凭着自己的理解和一些资料去设计这么一个程序

主要利用到了redis的string和set,string主要是利用它的k-v结构去对库存进行处理，也可以用list的数据结构来处理商品的库存，set则用来确保用户进行重复的提交

其中我们最主要解决的问题是

-防止并发产生超抢/超卖

2 流程设计

3 代码

3.1 服务端代码

class MiaoSha{

 const MSG_REPEAT_USER = '请勿重复参与';
 const MSG_EMPTY_STOCK = '库存不足';
 const MSG_KEY_NOT_EXIST = 'key不存在';

 const IP_POOL = 'ip_pool';
 const USER_POOL = 'user_pool';

 /** @var Redis */
 public $redis;
 public $key;

 public function __construct($key = '')
 {
  $this->checkKey($key);
  $this->redis = new Redis(); //todo 连接池
  $this->redis->connect('127.0.0.1');
 }

 public function checkKey($key = '')
 {
  if(!$key) {
   throw new Exception(self::MSG_KEY_NOT_EXIST);
  } else {
   $this->key = $key;
  }
 }

 public function setStock($value = 0)
 {
  if($this->redis->exists($this->key) == 0) {
   $this->redis->set($this->key,$value);
  }
 }

 public function checkIp($ip = 0)
 {
  $sKey = $this->key . self::IP_POOL;
  if(!$ip || $this->redis->sIsMember($sKey,$ip)) {
   throw new Exception(self::MSG_REPEAT_USER);
  }
 }

 public function checkUser($user = 0)
 {
  $sKey = $this->key . self::USER_POOL;
  if(!$user || $this->redis->sIsMember($sKey,$user)) {
   throw new Exception(self::MSG_REPEAT_USER);
  }
 }

 public function checkStock($user = 0, $ip = 0)
 {
  $num = $this->redis->decr($this->key);
  if($num < 0 ) {
   throw new Exception(self::MSG_EMPTY_STOCK);
  } else {
   $this->redis->sAdd($this->key . self::USER_POOL, $user);
   $this->redis->sAdd($this->key . self::IP_POOL, $ip);
   //todo add to mysql
   echo 'success' . PHP_EOL;
   error_log('success' . $user . PHP_EOL,3,'/var/www/html/demo/log/debug.log');
  }
 }

 /**
  * @note:此种做法不能防止并发
  * @func checkStockFail
  * @param int $user
  * @param int $ip
  * @throws Exception
  */
 public function checkStockFail($user = 0,$ip = 0) {
  $num = $this->redis->get($this->key);
  if($num > 0 ){
   $this->redis->sAdd($this->key . self::USER_POOL, $user);
   $this->redis->sAdd($this->key . self::IP_POOL, $ip);
   //todo add to mysql
   echo 'success' . PHP_EOL;
   error_log('success' . $user . PHP_EOL,3,'/var/www/html/demo/log/debug.log');
   $num--;
   $this->redis->set($this->key,$num);
  } else {
   throw new Exception(self::MSG_EMPTY_STOCK);
  }
 }
}

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php和redis实现秒杀活动的流程

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