Shortlyx - High-Performance URL Shortener

Shortlyx is a production-grade URL shortening service engineered for high throughput and low latency. It leverages a layered architecture with Redis-buffered writes to handle traffic spikes efficiently, decoupling real-time request processing from database persistence.

Architectural Highlights

1. High-Throughput Write Buffering

Traditional URL shorteners hit the database for every click event, creating a bottleneck at scale. Shortlyx implements a Write-Behind strategy:

• Ingestion: Click events are atomically incremented in Redis (INCR).
• Buffering: Affected keys are tracked in a Redis Set.
• Persistence: A background worker asynchronously flushes aggregated stats to PostgreSQL.
• Result: Transforms O(N) database writes into O(1) batch updates per interval, significantly increasing write capacity.

2. Layered "Hexagonal" Design

The codebase follows strict separation of concerns to ensure maintainability and testability:

• Handlers (Transport): HTTP/JSON logic (Gin).
• Service (Business Logic): Validations, Caching rules, and domain logic.
• Repository (Data Access): Abstractions for PostgreSQL and Redis.

3. Rate Limiting & Security

• Token Bucket Algorithm: Implemented via Redis to prevent abuse.
• Secure Headers: Configurable Proxy Trust for accurate IP rate limiting in load-balanced environments.

4. Optimized ID Generation

• Base62 Encoding: Efficiently maps unique Integer IDs to short alphanumeric strings.
• Database Sequences: Utilizes PostgreSQL BIGSERIAL for collision-free, sequential ID generation, ensuring shortest possible URLs.

Technology Stack

• Language: Go (Golang) 1.25+
• Web Framework: Gin
• Database: PostgreSQL 15+
• Caching / Broker: Redis 7.x
• Containerization: Docker Support (Planned)

API Reference

1. Shorten URL

POST /shorten

Request:

{
  "long_url": "https://www.google.com/search?q=system+design",
  "ttl_days": 7
}

Response:

{
  "short_url": "http://localhost:8080/1b"
}

2. Resolve URL

GET /:code

• Redirects to the original long_url.
• Asynchronously increments click count via Redis buffer.

3. Get Stats

GET /api/stats/:code

Response:

{
  "short_code": "1b",
  "long_url": "https://...",
  "click_count": 42,
  "created_at": "2024-01-01T12:00:00Z"
}

Setup & Installation

Prerequisites:

• Go 1.25+
• PostgreSQL
• Redis

Configuration: Create a .env file in the root directory:

PORT=8080
APP_ENV=development
DATABASE_URL=postgres://user:pass@localhost:5432/shortlyx?sslmode=disable
REDIS_URL=redis://localhost:6379/0

Running the Application:

# Install dependencies
go mod download

# Run migrations (ensure DB exists)
# (Manual SQL execution of migrations/001_create_urls.sql required)

# Start server
go run main.go