php如何防止超发,PHP+redis实现的限制抢购防止商品超发功能详解
本文實(shí)例講述了php+redis實(shí)現(xiàn)的限制搶購防止商品超發(fā)功能。分享給大家供大家參考，具體如下：
redis不僅僅是單純的緩存，它還有一些特殊的功能，在一些特殊場景上很好用。redis中key的原子自增incrby和判斷key不存在再寫入的setnx方法，可以有效的防止超發(fā)。
下面使用兩個(gè)不同的方式來說明利用redis做商品購買庫存數(shù)量限制。
業(yè)務(wù)場景很簡單，就是限制搶購5個(gè)商品，模擬并發(fā)請求搶購商品，每搶購一次對應(yīng)redis中的key值增加一次，通過判斷限購的數(shù)量來限制搶購，搶購成功寫入成功日志，失敗寫入失敗的信息記錄，通過記錄的數(shù)量來判斷是否超發(fā)。
文件index.php
require_once './myredis.php';
require_once './function.php';
class sendaward{
public $conf = [];
const v1 = 'way1';//版本一
const v2 = 'way2';//版本二
const amountlimit = 5;//搶購數(shù)量限制
const incramount = 1;//redis遞增數(shù)量值
//初始化調(diào)用對應(yīng)方法執(zhí)行商品發(fā)放
public function __construct($conf,$type){
$this->conf = $conf;
if(empty($type))
return '';
if($type==self::v1){
$this->way1(self::v1);
}elseif($type==self::v2){
$this->way2(self::v2);
}else{
return '';
}
}
//搶購商品方式一
protected function way1($v){
$redis = new myredis($this->conf);
$keynmae = getkeyname($v);
if(!$redis->exists($keynmae)){
$redis->set($keynmae,0);
}
$curramount = $redis->get($keynmae);
if(($curramount+self::incramount)>self::amountlimit){
writelog("沒有搶到商品",$v);
return;
}
$redis->incrby($keynmae,self::incramount);
writelog("搶到商品",$v);
}
//搶購商品方式二
protected function way2($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("沒有搶到商品",$v);
return;
}
writelog("搶到商品",$v);
}
}
//實(shí)例化調(diào)用對應(yīng)執(zhí)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
/**
* @desc 自定義redis操作類
* **/
class myredis{
public $handler = null;
public function __construct($conf){
$this->handler = new redis();
$this->handler->connect($conf['host'], $conf['port']); //連接redis
//設(shè)置密碼
if(isset($conf['auth'])){
$this->handler->auth($conf['auth']); //密碼驗(yàn)證
}
//選擇數(shù)據(jù)庫
if(isset($conf['db'])){
$this->handler->select($conf['db']);//選擇數(shù)據(jù)庫2
}else{
$this->handler->select(0);//默認(rèn)選擇0庫
}
}
//獲取key的值
public function get($name){
return $this->handler->get($name);
}
//設(shè)置key的值
public function set($name,$value){
return $this->handler->set($name,$value);
}
//判斷key是否存在
public function exists($key){
if($this->handler->exists($key)){
return true;
}
return false;
}
//當(dāng)key不存在的設(shè)置key的值，存在則不設(shè)置
public function setnx($key,$value){
return $this->handler->setnx($key,$value);
}
//將key的數(shù)值增加指定數(shù)值
public function incrby($key,$value){
return $this->handler->incrby($key,$value);
}
}
文件function.php
//獲取商品key名稱
function getkeyname($v)
{
return "send_goods_".$v;
}
//日志寫入方法
function writelog($msg,$v)
{
$log = $msg.php_eol;
file_put_contents("log/$v.log",$log,file_append);
}
1.ab工具并發(fā)測試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
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 搶到商品
2 搶到商品
3 搶到商品
4 搶到商品
5 搶到商品
6 搶到商品
7 沒有搶到商品
8 沒有搶到商品
9 沒有搶到商品
10 沒有搶到商品
11 沒有搶到商品
12 沒有搶到商品
觀察日志發(fā)現(xiàn) 搶到商品的記錄有6條超過正常的5條，說明超發(fā)了
2.ab工具并發(fā)測試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
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 搶到商品
2 搶到商品
3 搶到商品
4 搶到商品
5 沒有搶到商品
6 搶到商品
7 沒有搶到商品
8 沒有搶到商品
9 沒有搶到商品
10 沒有搶到商品
總結(jié)：觀察日志可知搶到商品的日志記錄是5條并沒有超發(fā)，說明利用這種方式可以限制住庫存的數(shù)量。之所以超發(fā)是因?yàn)榉椒ㄒ恢型ㄟ^加法來判斷限制條件的同時(shí)，并發(fā)一大，就會越過這個(gè)判斷條件出現(xiàn)會超發(fā)，redis的在這方面就體現(xiàn)優(yōu)勢了。
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