laravel解决超卖的几个方法

数据库字段

1 错误的示范

1. function test1()
2. {
3. $id = request()->input('id');
4. $product = Product::where('id', $id)->firstOrFail();
5. if ($product->num <= 0) return "卖光啦！！";
6. $product->decrement('num'); //库存减1
7. return "success";
8. }

使用 go 模拟并发

1. package main
2. import (
3. "fmt"
4. "github.com/PeterYangs/tools/http"
5. "sync"
6. )
7. func main() {
8. client := http.Client()
9. wait := sync.WaitGroup{}
10. for i := 0; i < 50; i++ {
11. wait.Add(1)
12. go func(w *sync.WaitGroup) {
13. defer w.Done()
14. res, _ := client.Request().GetToString("http://www.api/test1?id=1")
15. fmt.Println(res)
16. }(&wait)
17. }
18. wait.Wait()
19. }

2 方案1 redis 原子锁

1. function test2()
2. {
3. $id = request()->input('id');
4. $lock = \Cache::lock("product_" . $id, 10);
5. try {
6. //最多等待5秒，5秒后未获取到锁，则抛出异常
7. $lock->block(5);
8. $product = Product::where('id', $id)->firstOrFail();
9. if ($product->num <= 0) {
10. return "卖光啦！！";
11. }
12. $product->decrement('num');
13. return 'success';
14. }catch (LockTimeoutException $e) {
15. return '当前人数过多';
16. } finally {
17. optional($lock)->release();
18. }
19. }

3 方案2 mysql 悲观锁

1. function test3()
2. {
3. $id = request()->input('id');
4. try {
5. \DB::beginTransaction();
6. $product = Product::where('id', $id)->lockForUpdate()->first();
7. if ($product->num <= 0) {
8. return "卖光啦！！";
9. }
10. $product->decrement('num');
11. \DB::commit();
12. return "success";
13. } catch (\Exception $exception) {
14. }
15. }

库存正常

4 方案3 mysql 乐观锁

1. function test4()
2. {
3. $id = request()->input('id');
4. $product = Product::where('id', $id)->first();
5. if ($product->num <= 0) {
6. return "卖光啦！！";
7. }
8. //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
9. $res = \DB::update('UPDATE `product` SET num = num -1 WHERE id = ? AND num=?', [$id, $product->num]);
10. if (!$res) {
11. return '当前人数过多';
12. }
13. return 'success';
14. }

库存正常
优化乐观锁
修改库存的 sql 修改为
\DB::update(‘UPDATE product SET num = num -1 WHERE id = ? AND num-1 >= 0’, [$id]);

5 方案4 redis 存储库存

1. function test5()
2. {
3. $id = request()->input('id');
4. $num = Redis::command('get', ['product_' . $id]);
5. if ($num <= 0) {
6. return "卖完啦！";
7. }
8. $re = Redis::command('decrby', ['product_' . $id, 1]);
9. //减多了回滚
10. if ($re < 0) {
11. Redis::command('incrby', ['product_' . $id, 1]);
12. return "卖完啦！";
13. }
14. return 'success';
15. }

库存正常
原文链接：https://blog.csdn.net/weixin_41882200/article/details/119249367
欢迎补充