Redis queue realizes second kill

Features of seckill system

1、 The number of people snapping up is far more than the inventory , Read write concurrency is huge .

2、 The stock is low , Write less effectively .

3、 Writing needs strong consistency , Goods cannot be sold beyond .

4、 Reading consistency is not high .

5、 Stability is difficult ： High and low , A small dependency may directly cause an avalanche 、 It is difficult to predict the flow accurately , Too high also causes avalanches . Distributed cluster , There are many machines , The probability of failure is high .

6、 Accuracy is difficult ： stock 、 Number of successful rush purchases , Create consistency between the number of orders .

7、 High performance difficult ： We need to achieve extreme performance at limited cost .

Seckill system —— Principles of Architecture

1、 stability ： Reduce third-party dependence , At the same time, its own service deployment also needs to be isolated . Pressure measurement 、 Downgrade 、 Current limiting scheme 、 Ensure that core services are available . Health detection mechanism is needed , The whole link avoids single point .

2、 High performance ： Shorten the single request access path , Reduce IO. Reduce the number of interfaces , Reduce data throughput , Fewer requests .

Seckill service core implementation

1、 How to design seckill service ： Meet basic needs , Achieve the ultimate performance of single service . Request link traffic optimization , Optimize every layer from client to server . Stability building .

2、 Basic needs ： Inventory deduction 、 Check inventory 、 Queue progress .（ Achieve the ultimate performance of single service ）. Check the order details 、 Create order , Payment order .（ The number of people who rush to buy is far more than inventory , Read write concurrency is high ）

Basic needs —— Inventory deduction scheme

1、 Order less stock ？

Concurrent request ——> Create order ——> Inventory deduction ——> payment This process will not oversold , But the problem is that if someone places an order maliciously and doesn't pay , Occupy inventory .

2、 Pay less inventory ？

Concurrent request ——> Create order ——> payment ——> Inventory deduction This process is to pay for one-time deduction of inventory , If the user has finished buying the goods , Other users cannot place orders or orders are oversold .

3、 Withholding stock ？

Concurrent request ——> Inventory deduction ——> Create order ——> payment ——>10 Cancel the order without payment within minutes , Add inventory .

It is better to adopt the withholding inventory scheme .

wxml

<view>
  <l-countdown time-type="second" time="{
   {expire_time}}" bind:linend="changeBtn"/>

  <view><image src="{
   {Detail.image}}" bindtap="image"></image></view>
  <view>{
   {Detail.store_product.store_name}}</view>
  <view>{
   {Detail.price}}</view>

    <view>
      <l-button disabled="{
   { disabled }}" bind:lintap="buyGoods" type="error" data-id="{
   {Detail.id}}"> Kill immediately </l-button>
     </view>
</view>

js

// pages/Detail/Detail.js
Page({

  /**
   *  Initial data of the page 
   */
  data: {
    expire_time:0,
    disabled:false,
    expire_time:'',

  },

  /**
   *  Life cycle function -- Monitor page loading 
   */
  onLoad(options) {
    let that = this
    let sid = options.id
    wx.request({
      url: 'http://www.wej.com/index.php/api/seckill/goodsDetail', // Just for the sample , Not a real interface address 
      data: {
        sid
      },
      header: {
        'content-type': 'application/json' //  The default value is 
      },
      success (res) {
        console.log(res.data) 
        let newdate = Math.round(new Date().getTime() / 1000).toString()
        let expire_time = res.data.data.start_time - newdate
        console.log(expire_time)
        that.setData({
          Detail:res.data.data,
          expire_time:expire_time
        })
        if(expire_time > 0){
          that.setData({
            disabled:true
          })
        }else{
          that.setData({
            disabled:false
          })
        }
      }
    })


  },

  buyGoods(c){
    clearTimeout(this.TimeID);
    this.TimeID = setTimeout(() => {
      let goods_id = c.currentTarget.dataset.id
      wx.request({
        url: 'http://www.wej.com/index.php/api/seckill/snap_up', // Just for the sample , Not a real interface address 
        data: {
          goods_id
        },
        header: {
          'content-type': 'application/json' //  The default value is 
        },
        success (res) {
          console.log(res.data)
        }
      })
    }, 1000);

  },


changeBtn(){
  console.log(' The second kill begins ')
    this.setData({
      disabled:false
    })
  },




image(c){
  wx.previewImage({
    current: this.data.Detail.image, //  The  http  link 
    urls: [this.data.Detail.image] //  Pictures that need to be previewed  http  Link list 
  })
},


})

json

{
  "usingComponents": {
    "l-countdown":"/dist/countdown",
    "l-button":"/dist/button"
  }
}

<?php

namespace App\Http\Controllers;

use App\Models\AddressInfo;
use App\Models\StoreOrder;
use App\Server\Snowflake;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Redis;

class Seckill extends Controller
{
    /**
     *  Data preheating 
     * @return \Illuminate\Http\JsonResponse
     */
    public function activity()
    {
        $result = \App\Models\Seckill::with('StoreProduct')
            ->get()->toArray();
        foreach ($result as $val){
            // Generate the corresponding commodity inventory queue 
            $goods = "activity_goods_".$val['product_id'];
            for ($i=0; $i < $val['stock']; $i++) {
                Redis::lpush($goods,1);
            }
        }
        return response()->json(['code' => 20000, 'msg' => ' The query is successful ', 'data' => $result]);
    }

    /**、
     *  Second kill list 
     * @return \Illuminate\Http\JsonResponse
     */
    public function activityList()
    {
        $result = \App\Models\Seckill::with('StoreProduct')
            ->get()->toArray();
        return response()->json(['code' => 20000, 'msg' => ' The query is successful ', 'data' => $result]);
    }

    /**
     *  Second kill product details 
     * @return \Illuminate\Http\JsonResponse
     */
    public function goodsDetail()
    {
        $goods_id = request()->get('sid');
        $result = \App\Models\Seckill::with(['StoreProduct'])
            ->where('product_id',$goods_id)
            ->first();
        return response()->json(['code' => 20000, 'data' => $result, 'msg' => ' The query is successful ']);
    }

    /**
     *  Verify inventory 
     * @return \Illuminate\Http\JsonResponse
     */
    public function snap_up(){
        // user ID
        $userID = 1;
        // goods ID
        $goodsID = request()->get('goods_id');
        // Corresponding commodity inventory queue 
        $goods = "activity_goods_".$goodsID;
        // Set of users who have successfully snapped up corresponding products  {1,3,4}
        $robSuccessUser = "success_user".$goodsID;
        // Judge whether the current user is in the queue of successful robbery 
        $result = Redis::sismember($robSuccessUser,$userID);
        // If you're in here , It's over 
        if ($result) {
            // If the rush is successful   Return status code , Place an order 
            return response()->json(['code' => 20000, 'data' => '', 'msg' => ' It has been snapped up ']);
        }
        // Reduce inventory , Turn the data in the queue from the left   head 
        $count = Redis::lpop($goods);
        if (!$count) {
            // If the rush is successful   Return status code , Place an order 
            return response()->json(['code' => 20001, 'data' => '', 'msg' => ' It's all gone ']);
        }
        // Put the current spike uid Store it in the queue of successful rush purchase set
        $success = Redis::sadd($robSuccessUser, $userID);
        if(!$success){
            // Already in the success queue , Add back inventory , To prevent concurrent requests from the same user 
            Redis::lpush($goods, 1);
            // If the rush is successful   Return status code , Place an order 
            return response()->json(['code' => 20002, 'data' => '', 'msg' => ' It has been snapped up ']);
        }
        // If the rush is successful   Return status code , Place an order 
        return response()->json(['code' => 20000, 'data' => '', 'msg' => ' Seckill success ']);
    }

    /**
     *  Generate order 
     * @return false|\Illuminate\Http\JsonResponse|string
     */
    public function createOrder(){
        // user ID
        $userID = request()->get('userID');
        // goods ID
        $goodsID = request()->get('goods_id');
        // Address ID
        $address_id = request()->get('address_id');
        // Set of users who have successfully snapped up corresponding products 
        $robSuccessUser = "success_user".$goodsID;
        // Judge whether the current user is in the queue of successful robbery 
        $result = Redis::sismember($robSuccessUser,$userID);
        // If you're in here , It's over 
        if (!$result) {
            // If the rush is successful   Return status code , Place an order 
            return response()->json(['code' => 20003, 'data' => '', 'msg' => ' Hands slow ！']);
        }
        DB::beginTransaction();
        try{
            // Reduce inventory 
            $shopData = \App\Models\Seckill::with('StoreProduct')
                ->where('product_id',$goodsID)
                ->first()->toArray();
            $shopStock = \App\Models\Seckill::where('product_id',$goodsID)->update(['stock' => $shopData['stock'] - 1]);
            if (!$shopStock) return json_encode(['code' => 50000,'msg' => ' Order failure ','data' => []]);
            // Address 
            $address_info = AddressInfo::find($address_id)->toArray();
            // Generate order 
            Snowflake::machineId($userID);
            $order_id = substr(date('Ymd'),2).'-'.Snowflake::createOnlyId();
            $data = [
                'order_id' => $order_id,
                'uid' => $userID,
                'real_name' => $address_info['real_name'],
                'user_phone' => $address_info['phone'],
                'user_address' => $address_info['detail'],
                'pay_price' => $shopData['store_product']['price'],
                'pay_time' => time()
            ];
            $orderAdd = StoreOrder::insert($data);
            if (!$orderAdd) return json_encode(['code' => 50000,'msg' => ' Order failure ','data' => []]);
            DB::commit();
            // checkout success , Jump to the payment page 
            return response()->json(['code' => 20000, 'data' => '', 'msg' => ' checkout success ！']);
        }catch (\Exception $e){
            DB::rollBack();
            return response()->json(['code' => 50000, 'data' => '', 'msg' => $e->getMessage()]);
        }
    }


}