php+redis消息队列实现抢购功能

<?php
/
 抢购模块

 @author liubin
 @date 2016-02-10

 ab -n 1000 -c 100 http://192.168.16.73/Seckill/buy.php

/
class seckill extends mon
{

 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':
    $this->order_check_mysql($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 order_check_mysql($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$sql_forlock如果不加事务，只加写锁
    第一个会话读$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$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;
  }
  $key = 'goods_list_'.$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mit之前才会锁定
     出现超卖跟事务的一致性不冲突
     
    
     2$sql_forlock如果加了事务，又加读锁
     开启事务
     第一个会话读$sql_forlock时加读锁，并发时，第二个会话也允许获得$sql_forlock的读锁，
     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$sql_forlock如果加了事务，又加写锁
     开启事务
     第一个会话读$sql_forlock时加写锁，直到mit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'];
    $sql_inventory = 'UPDATE goods SET counts = counts - 1 WHERE id = '.$gid;
    $result = $this->_goodsModel->exect($sql_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();

    $sql = 'insert into orders (id,order_id,goods_id,uid,addtime) values ('.$data['id'].',"'.$data['order_id'].'","'.$data['goods_id'].'","'.$data['uid'].'","'.$data['addtime'].'")';   
    $result = $pdo->exec($sql);
    if(!$result){
     $pdo->rollBack();
     $this->_error = '订单创建失败';
     return false;
    }
    $pdo->mit();//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;
 }
}