看下面程式碼,一個簡單的減庫存模擬.

一,併發扣庫存

1.原始資料裡面有100個庫存

2.下面進行減庫存操作,程式碼如下所示

        $model = new Test();
        $data = $model->get(1);
        $count = $data['count'];
        $model->update(['id' => 1, 'count' => $count - 1]);

3.併發10,模擬100個請求

ab.exe -c 10 -n 100 http://www.tp5.net/
哈哈, 理論上count應該是0對吧,但是我們看看實際的結果

4.我們利用mysql的自減函式,換一個程式碼試試

        $model = new Test();
$model->where('id', 1)->setDec('count');

正常了,變成0了

        $model = new Test();
$model->where('id', 1)->setDec('count');

二,併發新增資料

1.100個併發,這時候不在同一條資料,需要插入

        $model = new Test();
        $data = $model->order('id desc')->find();
        $count = $data['count'];
        $new_count = $count -1;
        $model->insert(['count'=>$new_count]);

ab.exe -c 100 -n 1000 http://www.tp5.net/

不好意思犯了一個錯誤,不要用mysql保留函式做欄位名,下面改為count改為stock_num

3.檔案鎖

        $fp = fopen(ROOT_PATH . "./lock.txt", "w+");
        if (flock($fp, LOCK_EX)) {
            $model = new Test();
            $data = $model->order('id desc')->find();
            $stock_num = $data['stock_num'];
            $new_stock_num = $stock_num - 1;
            $model->insert(['stock_num' => $new_stock_num]);
            flock($fp, LOCK_UN);
        } else {
            return data('0', 286, "系統繁忙稍後再試");
        }
        fclose($fp);

ab.exe -c 100 -n 1000 http://www.tp5.net/

4.redis鎖,其實原理和上面檔案鎖的原理類似

5.mysql悲觀鎖+事務

        $model = new Test();
        $model->startTrans();
        try {
            $data = $model->lock(true)->order('id desc')->find();
            $stock_num = $data['stock_num'];
            $new_stock_num = $stock_num - 1;
            $model->insert(['stock_num' => $new_stock_num]);
            $model->commit();
        } catch (\Exception $exception) {
            $model->rollback();
            throw $exception;
        }

6.mysql樂觀鎖+事務

        $model = new Test();
        $TestLogModel = new TestLog();
        $model->startTrans();
        try {
            $data = $model->order('id desc')->find();
            $stock_num = $data['stock_num'];
            $version = $data['version'];
            $new_stock_num =$stock_num-1;
            $stock_data = ['stock_num' => $new_stock_num,'version' => $version+1];
            $rows = $model->where(['id' => 1,'version' =>$version])->update($stock_data);
            if($rows == 1){
                $res = $TestLogModel->insert(['number' => $new_stock_num]);
                if($res){
                    $model->commit();
                }else{
                    throw new \Exception('插入失敗');
                }
            }else{
                throw new \Exception('更新失敗');
            }
        } catch (\Exception $exception) {
            $model->rollback();
            throw $exception;
        }

沒有出現重複資料,但是有資料丟失了