Twitter Clone Backend

Table of Contents

• About The Project
  • Build With
• Development Process
  • Stage 1
  • Stage 2
  • Stage 3
• ERD
• Caching Mechanism
  • Cache Expiration
• Lesson Learned

About The Project

A clone of the Twitter web application with features such as tweets, user profiles, and a news feed. I aimed to minimize the use of external Go libraries, leveraging Go's native features as much as possible. Some of the things I implemented can be found under Leeson Learned.

The frontend repository can be found at: https://github.com/ranjabi/twitter-clone-frontend

Build With

• Go
• PostgreSQL
• Redis
• CI/CD: Docker, Github Actions

ERD

Caching Mechanism

The user profile displays information such as the username, follower/following count, and recent tweets. The response structure is shown below, with the following information being cached.

userResponse := struct {
    Id                 int            `json:"id"`
    Username           string         `json:"username"`
    FollowerCount      int            `json:"followerCount"`
    FollowingCount     int            `json:"followingCount"`
    RecentTweetsLength int            `json:"recentTweetsLength"`
    RecentTweets       []models.Tweet `json:"recentTweets"`
}

The decision tree of caching can be seen below. The cache is saved as key=user.id:{id}, value = userResponse for user profile information and key=user.id:{id}:recentTweets, value = recentTweets for the recent tweets.

is user.id:{id} exist?
    yes
    is user.id:{id}:recentTweets exist?
        yes
        -> return cache

        no
        cache miss for user.id:{id}:recentTweets
        get recentTweets from db and store it to cache
        -> return the combined data from db (recentTweets) and cache (userProfile)
    no
    get userProfile with recentTweets from db
    store it to cache
    -> return fully from db

Cache Expiration

Each time a user profile is added to the cache, the expiration time is set to 10 minutes. The following operations will delete the user's recent tweets cache:

• Creating, updating, or deleting a tweet
• Liking or unliking a tweet by a follower

As a result, the cache will be recreated when a follower requests the user's profile. Additionally, the expiration time resets to 10 minutes each time the user's profile is accessed.

Development Process

Stage 1

Features:

• Register
• Login
• Tweet (create, edit, delete)
• Follow/unfollow
• E2E Testing

Stage 2

Improvements:

• Refactored to layered architecture (handler, service, and repository)
• Request validation

Features:

• Like/unlike

Stage 3

Features:

• Implemented redis for user profile caching
• News feed

Lesson Learned

• Defined a custom HTTP appHandler for error handling, allowing structured error responses to be sent to the client.
• Implemented logging by capturing incoming HTTP requests. This logs the error method, request URL, and request body.