本文实例讲述了php+redis实现的限制抢购防止商品超发功能。分享给大家供大家参考，具体如下：
- redis不仅仅是单纯的缓存，它还有一些特殊的功能，在一些特殊场景上很好用。redis中key的原子自增incrby和判断key不存在再写入的setnx方法，可以有效的防止超发。
- 下面使用两个不同的方式来说明利用redis做商品购买库存数量限制。
- 业务场景很简单，就是限制抢购5个商品，模拟并发请求抢购商品，每抢购一次对应redis中的key值增加一次，通过判断限购的数量来限制抢购，抢购成功写入成功日志，失败写入失败的信息记录，通过记录的数量来判断是否超发。
文件index.php
<?php
require_once './myredis.php';
require_once './function.php';
class sendaward{
public $conf = [];
const v1 = 'way1';//版本一
const v2 = 'way2';//版本二
const amountlimit = 5;//抢购数量限制
const incramount = 1;//redis递增数量值
//初始化调用对应方法执行商品发放
public function __construct($conf,$type){
$this->conf = $conf;
if(empty($type))
return '';
if($type==self::v1){
$this->way1(self::v1);
}elseif($type==self::v2){
$this->way2(self::v2);
}else{
return '';
}
}
//抢购商品方式一
protected function way1($v){
$redis = new myredis($this->conf);
$keynmae = getkeyname($v);
if(!$redis->exists($keynmae)){
$redis->set($keynmae,0);
}
$curramount = $redis->get($keynmae);
if(($curramount+self::incramount)>self::amountlimit){
writelog("没有抢到商品",$v);
return;
}
$redis->incrby($keynmae,self::incramount);
writelog("抢到商品",$v);
}
//抢购商品方式二
protected function way2($v){
$redis = new myredis($this->conf);
$keynmae = getkeyname($v);
if(!$redis->exists($keynmae)){
$redis->setnx($keynmae,0);
}
if($redis->incrby($keynmae,self::incramount) > self::amountlimit){
writelog("没有抢到商品",$v);
return;
}
writelog("抢到商品",$v);
}
}
//实例化调用对应执行方法
$type = isset($_get['v'])?$_get['v']:'way1';
$conf = [
'host'=>'192.168.0.214','port'=>'6379',
'auth'=>'test','db'=>2,
];
new sendaward($conf,$type);
文件myredis.php
<?php
/**
* @desc 自定义redis操作类
* **/
class myredis{
public $handler = null;
public function __construct($conf){
$this->handler = new redis();
$this->handler->connect($conf['host'], $conf['port']); //连接redis
//设置密码
if(isset($conf['auth'])){
$this->handler->auth($conf['auth']); //密码验证
}
//选择数据库
if(isset($conf['db'])){
$this->handler->select($conf['db']);//选择数据库2
}else{
$this->handler->select(0);//默认选择0库
}
}
//获取key的值
public function get($name){
return $this->handler->get($name);
}
//设置key的值
public function set($name,$value){
return $this->handler->set($name,$value);
}
//判断key是否存在
public function exists($key){
if($this->handler->exists($key)){
return true;
}
return false;
}
//当key不存在的设置key的值，存在则不设置
public function setnx($key,$value){
return $this->handler->setnx($key,$value);
}
//将key的数值增加指定数值
public function incrby($key,$value){
return $this->handler->incrby($key,$value);
}
}
文件function.php
<?php
//获取商品key名称
function getkeyname($v)
{
return "send_goods_".$v;
}
//日志写入方法
function writelog($msg,$v)
{
$log = $msg.php_eol;
file_put_contents("log/$v.log",$log,file_append);
}
1.ab工具并发测试way1方法
[root@localhost oversend]# ab -c 100 -n 200 http://192.168.0.213:8083/index.php?v=way1
this is apachebench, version 2.3 <$revision: 655654 $>
copyright 1996 adam twiss, zeus technology ltd, http://www.zeustech.net/
licensed to the apache software foundation, http://www.apache.org/
benchmarking 192.168.0.213 (be patient)
completed 100 requests
completed 200 requests
finished 200 requests
server software: nginx
server hostname: 192.168.0.213
server port: 8083
document path: /index.php?v=way1
document length: 0 bytes
concurrency level: 100
time taken for tests: 0.089 seconds
complete requests: 200
failed requests: 0
write errors: 0
total transferred: 30600 bytes
html transferred: 0 bytes
requests per second: 2243.13 [#/sec] (mean)
time per request: 44.581 [ms] (mean)
time per request: 0.446 [ms] (mean, across all concurrent requests)
transfer rate: 335.16 [kbytes/sec] received
connection times (ms)
min mean[+/-sd] median max
connect: 0 6 2.2 5 17
processing: 2 28 16.3 25 55
waiting: 1 26 15.2 24 50
total: 5 34 16.3 30 60
percentage of the requests served within a certain time (ms)
50% 30
66% 35
75% 54
80% 56
90% 57
95% 60
98% 60
99% 60
100% 60 (longest request)
v1方法日志分析
[root@localhost log]# less -n way1.log 1 抢到商品 2 抢到商品 3 抢到商品 4 抢到商品 5 抢到商品 6 抢到商品 7 没有抢到商品 8 没有抢到商品 9 没有抢到商品 10 没有抢到商品 11 没有抢到商品 12 没有抢到商品
观察日志发现 抢到商品的记录有6条超过正常的5条，说明超发了
2.ab工具并发测试way2方法
[root@localhost oversend]# ab -c 100 -n 200 http://192.168.0.213:8083/index.php?v=way2
this is apachebench, version 2.3 <$revision: 655654 $>
copyright 1996 adam twiss, zeus technology ltd, http://www.zeustech.net/
licensed to the apache software foundation, http://www.apache.org/
benchmarking 192.168.0.213 (be patient)
completed 100 requests
completed 200 requests
finished 200 requests
server software: nginx
server hostname: 192.168.0.213
server port: 8083
document path: /index.php?v=way2
document length: 0 bytes
concurrency level: 100
time taken for tests: 0.087 seconds
complete requests: 200
failed requests: 0
write errors: 0
total transferred: 31059 bytes
html transferred: 0 bytes
requests per second: 2311.68 [#/sec] (mean)
time per request: 43.259 [ms] (mean)
time per request: 0.433 [ms] (mean, across all concurrent requests)
transfer rate: 350.58 [kbytes/sec] received
connection times (ms)
min mean[+/-sd] median max
connect: 0 6 5.4 5 13
processing: 3 31 16.6 30 70
waiting: 1 30 16.6 30 70
total: 5 37 18.5 32 82
percentage of the requests served within a certain time (ms)
50% 32
66% 41
75% 45
80% 50
90% 68
95% 80
98% 81
99% 82
100% 82 (longest request)
v2方法日志分析
[root@localhost log]# less -n v2.log [root@localhost log]# less -n way2.log 1 抢到商品 2 抢到商品 3 抢到商品 4 抢到商品 5 没有抢到商品 6 抢到商品 7 没有抢到商品 8 没有抢到商品 9 没有抢到商品 10 没有抢到商品
总结：观察日志可知抢到商品的日志记录是5条并没有超发，说明利用这种方式可以限制住库存的数量。之所以超发是因为方法一中通过加法来判断限制条件的同时，并发一大，就会越过这个判断条件出现会超发，redis的在这方面就体现优势了。
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