使用laravel解决库存超出的几个方案

数据库字段

1. 错误的示范

2021-06-08 10:57:59
* @return string
*/
function test1()
{

//商品id
$id = request()->input('id');

$product = Product::where('id', $id)->firstOrFail();

if ($product->num <= 0) {

return "卖光啦！！";
}

//库存减1
$product->decrement('num');

return "success";

}

使用 go 模拟并发

package main

import (
"fmt"
"github.com/PeterYangs/tools/http"
"sync"
)

func main() {

client := http.Client()

wait := sync.WaitGroup{}

for i := 0; i < 50; i++ {

wait.Add(1)

go func(w *sync.WaitGroup) {

defer w.Done()

res, _ := client.Request().GetToString("http://www.api/test1?id=1")

fmt.Println(res)

}(&wait)

}

wait.Wait()

}

在数据库中查看库存

库存已超出

2.redis 原子锁

2021-06-08 11:00:31
*/
function test2()
{
//商品id
$id = request()->input('id');

$lock = \Cache::lock("product_" . $id, 10);

try {

//最多等待5秒，5秒后未获取到锁，则抛出异常
$lock->block(5);

$product = Product::where('id', $id)->firstOrFail();

if ($product->num <= 0) {

return "卖光啦！！";
}
//库存减1
$product->decrement('num');

return 'success';

}catch (LockTimeoutException $e) {

return '当前人数过多';

} finally {

optional($lock)->release();
}
}

库存正常

3.mysql 悲观锁

2021-06-08 11:00:47
*/
function test3()
{

//商品id
$id = request()->input('id');

try {
\DB::beginTransaction();
$product = Product::where('id', $id)->lockForUpdate()->first();

if ($product->num <= 0) {

return "卖光啦！！";
}

//库存减1
$product->decrement('num');

\DB::commit();

return "success";

} catch (\Exception $exception) {

}

}

库存正常

4.mysql 乐观锁

2021-06-08 11:00:47
*/
function test4()
{

//商品id
$id = request()->input('id');

$product = Product::where('id', $id)->first();

if ($product->num <= 0) {

return "卖光啦！！";
}

//修改前检查库存和之前是否一致，不一致说明已经有变动，则放弃更改
$res = \DB::update('UPDATE `product`, [$id, $product->num]);

if (!$res) {

return '当前人数过多';

}

return 'success';


}

库存正常

优化乐观锁

修改库存的 sql 修改为

\DB::update('UPDATE `product`, [$id]);

5.redis 存储库存

2021-06-15 15:18:31
* @return string
*/
function test5()
{

//商品id
$id = request()->input('id');


$num = Redis::command('get', ['product_' . $id]);


if ($num <= 0) {

return "卖完啦！";
}

//减库存
$re = Redis::command('decrby', ['product_' . $id, 1]);


//减多了回滚
if ($re < 0) {

Redis::command('incrby', ['product_' . $id, 1]);


return "卖完啦！";

}

return 'success';

}