1. Design

Note

• folder structure follow google/exposure-notifications-server
• The standard library now has all you need for advanced routing in Go

1.1 API

Four APIs as follow:

• POST /api/v1/data/shorten:
  • with body {longUrl: longURLString}
  • return: shortURL
• GET /api/v1/shortUrl:
  • return status 302
  • return longUrl for redirect
• GET /shortUrl: redirect to GET /api/v1/shortUrl
• GET /: UI

1.2

• POST /api/v1/data/shorten:

  • when longURL comes in, check if usl not exists in database
    • if not exists in => use snowflake ID to generate Index and insert => return shortURL
    • if might exist => search longURL
      • if exist url => return shortURl
      • not exist => insert

• GET /api/v1/shortUrl:

  • Plan 1: use bloom filter to check wether url exist in database first
  • Plan 2: use catch
  • Plan 3: do nothing

Note

Each api should:

1. check http method
2. check status
3. check input

Middleware should:

1. log input
2. recovery

How to route net/http

command

migrate

cd ./cmd/migrate
go build -o migrate.out
./migrate.out -path="../../migrations"

未來流程規劃

graph TD
    User((使用者)) --> LB[Load Balancer]
    LB --> Server[Web Servers]

    subgraph "Write Path（產生短網址)"
        Server --> Blacklist{1. 黑名單檢查<br/>Redis/Local Cache}
        Blacklist -- 命中黑名單 --> Refuse[回傳 403 Forbidden]
        Blacklist -- 安全 --> KeyGen[2. 產生短網址 Key]
        KeyGen --> WriteDB[(3. 寫入 Database)]
        WriteDB --> UpdateBF[4. 更新 Bloom Filter]
        UpdateBF --> UpdateCache[5. 寫入 Cache]
    end

    subgraph "Read Path (還原網址)"
        Server --> BF_Check{A. Bloom Filter<br/>檢查是否存在?}
        BF_Check -- 絕對不存在 --> 404[直接回傳 404]
        BF_Check -- 可能存在 --> CacheCheck{B. Cache 查詢<br/>Redis}
        
        CacheCheck -- Hit --> Redirect[回傳 302/301 導向]
        CacheCheck -- Miss --> DB_Query[(C. Database 查詢)]
        
        DB_Query -- 存在 --> SyncCache[更新 Cache]
        SyncCache --> Redirect
        DB_Query -- 不存在 --> 404_Real[回傳 404]
    end

    %% 零件定義
    subgraph "資料層"
        Redis[(Redis<br/>Cache + BloomFilter)]
        DB[(PostgreSQL/MySQL)]
    end

    %% 連接資料層
    UpdateCache -.-> Redis
    CacheCheck -.-> Redis
    WriteDB -.-> DB
    DB_Query -.-> DB
    UpdateBF -.-> Redis

Loading

how to debug

1. enter make up-debug in consule
2. use vscode dbug and launch Connect to Docker Debug