PHP+redis实现的限制抢购防止商品超发功能详解

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。

完整代码github地址

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