Redis learning - 06 drifting bottle case

Case introduction

Wechat has hundreds of millions of users , At one time, there may be thousands of people playing with drifting bottles at the same time , For such a service with high concurrency and small amount of data , Use Node.js and Redis It is definitely a recommended choice .

Interface design

Throw a drift bottle

• Request method ：POST
• Request path ：/
• Request body parameters ：
  • time： The timestamp of the bottle thrown , The default setting is Date.now()
  • owner： Drifting bottle owner （ user id）
  • type： Drift bottle type
    • male： men
    • female： women
  • content： Contents of the drifting bottle
• return ： Complete data content

Pick up a drifting bottle

• Request method ：GET
• Request path ：/
• Query parameters ：
  • user： The man who picks up the drifting bottle （ user id）
  • type： Drift bottle type
    • all： All
    • male： men
    • female： women
• Return the data ：

{
    
  "time": 1641883884765, //  The timestamp of the bottle thrown 
  "owner": 1, //  Drifting bottle owner 
  "type": "male", //  Drift bottle type 
  "content": "hello world" //  Contents of the drifting bottle 
}

Design thinking

Can be Redis Imagine a sea ,Redis Every one of them Hash Type of data is a drifting bottle , Each drifting bottle has a unique id（ namely Redis The key ）, It contains some information about the drifting bottle （ namely Redis The key value ）.

Use two databases , Store two types of type Drifting bottle , The purpose is to facilitate the use of Redis Medium RANDOMKEY command , This command returns a random key in the current database , Without any conditions .

When throwing a drift bottle , Create a unique id（ Use uuidv4）, With this id by key, The data of the drift bottle is the value , Add one Hash Data of type , And set up 1 Days .

When picking up drifting bottles , according to type Decide which database to randomly read data from , Once the drifting bottle is picked up , Just delete from the database .

Start developing

Initialize project

mkdir drift-bottle
cd drift-bottle
npm init -y
npm i express ioredis uuidv4

app.js：

const {
     uuid } = require('uuidv4')
const Redis = require('ioredis')
const express = require('express')

const app = express()
app.use(express.json())

//  establish  Redis  example 
const connectRedis = () => {
    
  return new Redis()
}

//  Throw a drift bottle 
app.post('/', (req, res, next) => {
    
  try {
    
  	res.send('post /')
  } catch (error) {
    
    next(error)
  }
})

//  Pick up a drifting bottle 
app.get('/', (req, res, next) => {
    
  try {
    
  	res.send('get /')
  } catch (error) {
    
    next(error)
  }
})

//  Unified handling of exceptions 
app.use((err, req, res, next) => {
    
  res.status(500).json({
    
    error: err.message
  })
})

app.listen(3000, () => {
    
  console.log('runnning')
})

Throw a drift bottle

//  Throw a drift bottle 
app.post('/', async (req, res, next) => {
    
  try {
    
    const bottle = req.body

    //  Set timestamp 
    bottle.time = bottle.time || Date.now()

    //  Randomly generate a non repeating... For each drift bottle id
    const bottleId = uuid()

    const type = {
    
      male: 0,
      female: 1
    }

    await redis
      .pipeline()
      //  Switch databases according to type 
      .select(type[bottle.type])
      //  Save the data as  Hash
      .hmset(bottleId, bottle)
      //  Set up  1  Days 
      .expire(bottleId, 24 * 60 * 60)
      .exec()

    res.status(201).json({
    
      bottle: {
    
        id: bottleId,
        ...bottle
      }
    })
  } catch (error) {
    
    next(error)
  }
})

Pick up a drifting bottle

//  Pick up a drifting bottle 
app.get('/', async (req, res, next) => {
    
  try {
    
    const query = req.query

    const type = {
    
      all: Math.round(Math.random()),
      male: 0,
      female: 1
    }

    query.type = query.type || 'all'

    //  Switch databases according to type 
    await redis.select(type[query.type])

    //  Pick one at random  key
    const bottleId = await redis.randomkey()

    if (!bottleId) {
    
      res.status(200).json({
    
        message: ' The sea is clean ...'
      })
    }

    //  According to the drift bottle  id  Get complete drift bottle information 
    const bottle = await redis.hgetall(bottleId)

    res.status(201).json({
    
      bottle
    })

    //  from  Redis  Delete the found drift bottle 
    redis.del(bottleId)
  } catch (error) {
    
    next(error)
  }
})