php+redis消息队列实现抢购功能

本文实例为大家分享PHP+redis消息队列实现抢购的具体代码,供大家参考,具体内容如下

实现功能

1. 基于redis队列,防止高并发的超卖 2. 基于MysqL的事务加排它锁,防止高并发的超卖

基于redis队列工作流程:

1. 管理员根据goods表中的库存,创建redis商品库存队列 2. 客户端访问秒杀API 3. web服务器先从redis的商品库存队列中查询剩余库存重点内容 4. redis队列中有剩余,则在MysqL中创建订单,去库存,抢购成功 5. redis队列中没有剩余,则提示库存不足,抢购失败重点内容

基于MysqL事务和排它锁工作流程:

1. 开启事务 2. 查询库存,并显示的设置写锁(排他锁):SELECT * FROM goods WHERE id = 1 FOR UPDATE 3. 生成订单 4. 去库存,隐示的设置写锁(排他锁):UPDATE goods SET counts = counts – 1 WHERE id = 1 5. commit,释放锁

注意:第二步步可以设置共享锁,不然有可能会造成死锁。

代码

rush:PHP;"> private $_orderModel = null;
private $_goodsModel = null;
private $_redis = null;
/*

  • 错误信息
    */
    protected $_error = '';
    /**
  • 构造器
  • /
    public function __construct()
    {
    if($this->_orderModel === null){
    $this->_orderModel = new OrderModel();
    }
    if($this->_goodsModel === null){
    $this->_goodsModel = new GoodsModel();
    }
    if($this->_redis === null){
    $this->_redis = new QRedis();
    }
    }
    /

  • 秒杀API
  • @author liubin
  • @date 2017-02-10
    /
    public function addQsec(){
    $gid = intval($_GET['gid']);
    $type = isset($_GET['type']) ? $_GET['type'] : 'MysqL';
    switch ($type) {
    case 'MysqL':
    $this->ordercheckMysqL($gid);
    echo $this->getError();
    break;
    case 'redis':
    $this->order_check_redis($gid);
    echo $this->getError();
    break;
    case 'transaction':
    $this->order_check_transaction($gid);
    echo $this->getError();
    break;
    default:
    echo '类型错误';
    break;
    }
    }
    /
  • 获取错误信息
  • @author liubin
  • @date 2017-02-10
    /
    public function getError(){
    return $this->_error;
    }
    /
  • 基于MysqL验证库存信息
  • @desc 高并发下会导致超卖
  • @author liubin
  • @date 2017-02-10
    */
    protected function ordercheckMysqL($gid){

$model = $this->_goodsModel;
$pdo = $model->getHandler();
$gid = intval($gid);

/*

  • 1:$sql_forlock如果不加事务,不加写锁:
  • 超卖非常严重,就不说了
  • 2:$sql_forlock如果不加事务,只加写锁:
  • 一个会话读$sql_forlock时加写锁,第一个会话$sql_forlock查询结束会释放该行锁.
  • 第二个会话在第一个会话释放后读$sql_forlock的写锁时,会再次$sql_forlock查库存
  • 导致超卖现象产生
  • /
    $sql_forlock = 'select
    from goods where id = '.$gid .' limit 1 for update';
    //$sql_forlock = 'select * from goods where id = '.$gid .' limit 1';
    $result = $pdo->query($sql_forlock,PDO::FETCH_ASSOC);
    $goodsInfo = $result->fetch();

if($goodsInfo['counts']>0){

//去库存
$gid = $goodsInfo['id'];
$sql_inventory = 'UPDATE goods SET counts = counts - 1 WHERE id = '.$gid;
$result = $this->_goodsModel->exect($sql_inventory);
if($result){
//创订单
$data = [];
$data['order_id'] = $this->_orderModel->buildOrderNo();
$data['goods_id'] = $goodsInfo['id'];
$data['addtime'] = time();
$data['uid'] = 1;
$order_rs = $this->_orderModel->create_order($data);
if($order_rs){
$this->_error = '购买成功';
return true;
}
}
}

$this->_error = '库存不足';
return false;

}
/*

  • 基于redis队列验证库存信息
  • @desc Redis是底层是单线程的,命令执行是原子操作,包括lpush,lpop等.高并发下不会导致超卖
  • @author liubin
  • @date 2017-02-10
    */
    protected function order_check_redis($gid){
    $goodsInfo = $this->_goodsModel->getGoods($gid);
    if(!$goodsInfo){
    $this->_error = '商品不存在';
    return false;
    }
    $key = 'goodslist'.$goodsInfo['id'];
    $count = $this->_redis->getHandel()->lpop($key);
    if(!$count){
    $this->_error = '库存不足';
    return false;
    }
    //生成订单
    $data = [];
    $data['order_id'] = $this->_orderModel->buildOrderNo();
    $data['goods_id'] = $goodsInfo['id'];
    $data['addtime'] = time();
    $data['uid'] = 1;
    $order_rs = $this->_orderModel->create_order($data);

//库存减少
$gid = $goodsInfo['id'];
$sql = 'UPDATE goods SET counts = counts - 1 WHERE id = '.$gid;
$result = $this->_goodsModel->exect($sql);
$this->_error = '购买成功';
return true;
}
/*

  • 基于MysqL事务验证库存信息
  • @desc 事务 和 行锁 模式,高并发下不会导致超卖,但效率会慢点
  • @author liubin
  • @date 2017-02-10

说明:
如果$sql_forlock不加写锁,并发时,$sql_forlock查询的记录存都大于0,可以减库存操作.
如果$sql_forlock加了写锁,并发时,$sql_forlock查询是等待第一次链接释放后查询.所以库存最多就是5

*/
protected function order_check_transaction($gid){

$model = $this->_goodsModel;
$pdo = $model->getHandler();
$gid = intval($gid);

try{
$pdo->beginTransaction();//开启事务处理

/*

  • 1:$sql_forlock如果只加事务,不加写锁:

  • 开启事务

  • 因为没有加锁,读$sql_forlock后,并发时$sql_inventory之前还可以再读。

  • $sql_inventory之后和commit之前才会锁定

  • 出现超卖跟事务的一致性不冲突

  • 2:$sql_forlock如果加了事务,又加读锁:

  • 开启事务

  • 一个会话读$sql_forlock时加读锁,并发时,第二个会话也允许获得$sql_forlock的读锁,

  • 但是在第一个会话执行去库存操作时(写锁),写锁便会等待第二个会话的读锁,第二个会话执行写操作时,写锁便会等待第一个会话的读锁,

  • 出现死锁

  • 3:$sql_forlock如果加了事务,又加写锁:

  • 开启事务

  • 一个会话读$sql_forlock时加写锁,直到commit才会释放写锁,并发查询不会出现超卖现象。

  • */

$sql_forlock = 'select from goods where id = '.$gid .' limit 1 for update';
//$sql_forlock = 'select
from goods where id = '.$gid .' limit 1 LOCK IN SHARE MODE';
//$sql_forlock = 'select * from goods where id = '.$gid .' limit 1';
$result = $pdo->query($sql_forlock,PDO::FETCH_ASSOC);
$goodsInfo = $result->fetch();

if($goodsInfo['counts']>0){

//去库存
$gid = $goodsInfo['id'];
$<a href="https://www.jb51.cc/tag/sql/" target="_blank" class="keywords">sql</a>_inventory = 'UPDATE goods SET counts = counts - 1 WHERE id = '.$gid;
$result = $this->_goodsModel->exect($<a href="https://www.jb51.cc/tag/sql/" target="_blank" class="keywords">sql</a>_inventory);

if(!$result){
 $pdo->rollBack();
 $this->_error = '库存减少失败';
 return false;
}

//创订单
$data    = [];
$data['id']   = 'null';
$data['order_id'] = $this->_orderModel->buildOrderNo();
$data['goods_id'] = $goodsInfo['id'];
$data['uid']  = 'abc';
$data['addtime'] = time();

$<a href="https://www.jb51.cc/tag/sql/" target="_blank" class="keywords">sql</a> = 'insert into orders (id,order_id,goods_id,uid,addtime) values ('.$data['id'].',"'.$data['order_id'].'","'.$data['goods_id'].'","'.$data['uid'].'","'.$data['addtime'].'")';   
$result = $pdo->exec($<a href="https://www.jb51.cc/tag/sql/" target="_blank" class="keywords">sql</a>);
if(!$result){
 $pdo->rollBack();
 $this->_error = '订单创建失败';
 return false;
}
$pdo->commit();//提交
$this->_error = '购买成功';
return true;

}else{
$this->_error = '库存不足';
return false;
}
}catch(PDOException $e){
echo $e->getMessage();
$pdo->rollBack();
}

}
/*

  • 创建订单
  • MysqL 事物处理,也可以用存储过程
  • */
    private function create_order($goodsInfo){
    //生成订单
    $data = [];
    $data['order_id'] = $this->_orderModel->buildOrderNo();
    $data['goods_id'] = $goodsInfo['id'];
    $data['addtime'] = time();
    $data['uid'] = 1;
    $order_rs = $this->_orderModel->create_order($data);

//库存减少
$gid = $goodsInfo['id'];
$sql = 'UPDATE goods SET counts = counts - 1 WHERE id = '.$gid;
$result = $this->_goodsModel->exect($sql);
return true;
}
}

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持编程之家。

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