php+redis一步一步测试秒杀

1、普通的秒杀查库减库存：

<?php
/**
100个用户同时访问100次会出现超卖
**/
//连接数据库
$dsn = "mysql:host=localhost;dbname=ceshi";
$db = new PDO($dsn, 'root', 'root');
//价格
$price=10;
//用户id
$user_id=1;
//商品id
$goods_id=1;
//skuid
$sku_id=11;
//数量
$number=1;
//生成唯一订单
function build_order_no(){
return date('ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}
//库存是否大于0
$sql="select number from ih_store where goods_id='$goods_id' and sku_id='$sku_id'";
$row=$db->query($sql)->fetch();
if($row['number']>0){//高并发下会导致超卖
$order_sn=build_order_no();
//生成订单
$sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
values('$order_sn','$user_id','$goods_id','$sku_id','$price')";
$order_rs=$db->exec($sql);
//库存减少
$sql="update ih_store set number=number-{$number} where sku_id='$sku_id'";
$store_rs=$db->exec($sql);
if($store_rs){
echo "库存减少成功";
}else{
echo "库存减少失败";
}
}else{
echo "库存不够";
}
?>

2、把数据库的库存字段设置为无符号：

<?php
/**
100个用户同时访问600次的情况下会出现超卖
**/
//连接数据库
$dsn = "mysql:host=localhost;dbname=ceshi";
$db = new PDO($dsn, 'root', 'root');
//价格
$price=10;
//用户id
$user_id=1;
//商品id
$goods_id=1;
//skuid
$sku_id=11;
//数量
$number=1;
//生成唯一订单
function build_order_no(){
return date('ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}
//库存是否大于0
$sql="select number from ih_store where goods_id='$goods_id' and sku_id='$sku_id'";
$row=$db->query($sql)->fetch();
if($row['number']>0){//高并发下会导致超卖
$order_sn=build_order_no();
//生成订单
$sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
values('$order_sn','$user_id','$goods_id','$sku_id','$price')";
$order_rs=$db->exec($sql);

//库存减少
$sql="update ih_store set number=number-{$number} where sku_id='$sku_id'";
$store_rs=$db->exec($sql);
if($store_rs){
echo "库存减少成功";
}else{
echo "库存减少失败";
}
}else{
echo "库存不够";
}
?>

3、采用排它锁解决:

<?php
/**
100个用户同时访问1500次的情况下会出现超卖
**/
//连接数据库
$dsn = "mysql:host=localhost;dbname=ceshi";
$db = new PDO($dsn, 'root', 'root');
//价格
$price=10;
//用户id
$user_id=1;
//商品id
$goods_id=1;
//skuid
$sku_id=11;
//数量
$number=1;
//生成唯一订单
function build_order_no(){
return date('ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}
//库存是否大于0
$sql="select number from ih_store where goods_id='$goods_id' and sku_id='$sku_id' FOR UPDATE";
$row=$db->query($sql)->fetch();
if($row['number']>0){//高并发下会导致超卖
$order_sn=build_order_no();
//生成订单
$sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
values('$order_sn','$user_id','$goods_id','$sku_id','$price')";
$order_rs=$db->exec($sql);
//库存减少
$db->beginTransaction();//开启事务处理
$sql="update ih_store set number=number-{$number} where sku_id='$sku_id'";
$store_rs=$db->exec($sql);
if($store_rs){
echo "库存减少成功";
$db->commit();
}else{
echo "库存减少失败";
}
}else{
$db->rollBack();
echo "库存不够";
}
?>

4、采用redis队列实现

第一步把库存存入队列中

<?php
//500个库存存入redis队列
$store=20;
$redis=new Redis();
$result=$redis->connect('127.0.0.1',6379);
$res=$redis->llen('goods_store');
$count=$store-$res;
for($i=0;$i<$count;$i++){
    $redis->lpush('goods_store',1);
}
echo $redis->llen('goods_store');
?>

队列操作：

<?php
/**
可以抗住任何并发
**/
//连接数据库
$dsn = "mysql:host=localhost;dbname=ceshi";
$db = new PDO($dsn, 'root', 'root');
//价格
$price=10;
//用户id
$user_id=1;
//商品id
$goods_id=1;
//skuid
$sku_id=11;
//数量
$number=1;

//生成唯一订单
function build_order_no(){
return date('ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}
//连接redis
$redis=new Redis();
$result=$redis->connect('127.0.0.1',6379);
// echo $redis->llen('goods_store');
// die;
$count=$redis->lpop('goods_store');
if(!$count){
    echo "redis队列无库存";
    return false;

}
//生成订单
$order_sn=build_order_no();
$sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
values('$order_sn','$user_id','$goods_id','$sku_id','$price')";
$order_rs=$db->exec($sql);

//库存减少
$sql="update ih_store set number=number-{$number} where sku_id='$sku_id'";
$store_rs=$db->exec($sql);
if($store_rs){
echo "库存减少成功";
}else{
echo "库存减少失败";
}
?>

ab测试：

ab -n 2000 -c 100 http://localhost/miaosha/index2.php

数据库导入

-- ----------------------------
-- Table structure for `ih_goods`
-- ----------------------------
DROP TABLE IF EXISTS `ih_goods`;
CREATE TABLE `ih_goods` (
  `goods_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `cat_id` int(11) NOT NULL,
  `goods_name` varchar(255) NOT NULL,
  PRIMARY KEY (`goods_id`)
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of ih_goods
-- ----------------------------
INSERT INTO `ih_goods` VALUES ('1', '0', '小米手机');

-- ----------------------------
-- Table structure for `ih_order`
-- ----------------------------
DROP TABLE IF EXISTS `ih_order`;
CREATE TABLE `ih_order` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `order_sn` char(32) NOT NULL,
  `user_id` int(11) NOT NULL,
  `status` int(11) NOT NULL DEFAULT '0',
  `goods_id` int(11) NOT NULL DEFAULT '0',
  `sku_id` int(11) NOT NULL DEFAULT '0',
  `price` float NOT NULL,
  `addtime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=21 DEFAULT CHARSET=utf8 COMMENT='订单表';

-- ----------------------------
-- Table structure for `ih_store`
-- ----------------------------
DROP TABLE IF EXISTS `ih_store`;
CREATE TABLE `ih_store` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `goods_id` int(11) NOT NULL,
  `sku_id` int(10) unsigned NOT NULL DEFAULT '0',
  `number` int(10) unsigned NOT NULL DEFAULT '0',
  `freez` int(11) NOT NULL DEFAULT '0' COMMENT '虚拟库存',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 COMMENT='库存';

-- ----------------------------
-- Records of ih_store
-- ----------------------------
INSERT INTO `ih_store` VALUES ('1', '1', '11', '20', '0');