本文实例为大家分享了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：
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：
- 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
-
$sql_inventory之后和commit之前才会锁定
-
出现超卖跟事务的一致性不冲突
-
2：$sql_forlock如果加了事务，又加读锁：
-
开启事务
-
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
-
*/
$sql_forlock = 'select from goods where id = '.$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;
}
}
