方案详解：使用laravel解决库存超出问题

    /**
     * 错误示范
     * Create by Peter Yang
     * 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！！";
        }

        //仓库减1
        $product->decrement('num');

        return "success";

    }

package mainimport (
    "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 wait.Done()

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

            fmt.Println(res)

        }(&wait)

    }

    wait.Wait()}

    /**
     * redis原子锁
     * Create by Peter Yang
     * 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！！";
            }
            //仓库减1
            $product->decrement('num');

            return 'success';

        }catch (LockTimeoutException $e) {

            return '当前人数过多';

        } finally {

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

    /**
     * mysql悲观锁
     * Create by Peter Yang
     * 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！！";
            }

            //仓库减1
            $product->decrement('num');

            \DB::commit();

            return "success";

        } catch (\Exception $exception) {

        }

    }

    /**
     * mysql乐观锁
     * Create by Peter Yang
     * 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
        $res = \DB::update('UPDATE `product` SET num = num -1 WHERE id = ? AND num=?', [$id, $product->num]);

        if (!$res) {

            return '当前人数过多';

        }

        return 'success';


    }

\DB::update('UPDATE `product` SET num = num -1 WHERE id = ? AND num-1 >= 0', [$id]);