• 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

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

完整代码github地址

01-06 00:08