Event Counter

A high-performance, concurrent event processing system built in Go that demonstrates advanced concurrency patterns, message queue integration, and real-time event aggregation.

🚀 Overview

This project implements a scalable microservice that processes events from RabbitMQ queues using Go's powerful concurrency primitives. It showcases real-world patterns for handling distributed message processing with automatic shutdown and JSON output generation.

✨ Key Features

• Concurrent Processing: Multi-worker architecture using goroutines and channels
• Message Deduplication: Ensures each message is processed exactly once
• Type-based Routing: Events are routed to specific channels based on event type
• Automatic Shutdown: Graceful shutdown after 5 seconds of inactivity
• JSON Export: Generates structured output files per event type
• Configurable: Dynamic RabbitMQ URL and exchange configuration

🏗️ Architecture

The system follows a producer-consumer pattern with the following components:

RabbitMQ Queue → Message Receiver → Type-based Channels → Worker Pool → Event Counters → JSON Output

Core Interface

type Consumer interface {
    Created(ctx context.Context, uid string) error
    Updated(ctx context.Context, uid string) error
    Deleted(ctx context.Context, uid string) error
}

Message Format

{
    "id": "unique-message-identifier"
}

Routing Key Pattern: <user-id>.event.<event-type> Queue Name: eventcountertest

🛠️ Technical Highlights

• Goroutines & Channels: Efficient concurrent processing
• Context Management: Proper cancellation and timeout handling
• Sync Package: Thread-safe operations and synchronization
• Message Queue Integration: RabbitMQ with AMQP protocol
• Clean Architecture: Modular design with clear separation of concerns

🚀 Quick Start

Prerequisites

• Go 1.19+
• Docker & Docker Compose
• Make

Installation

1. Clone the repository

   git clone https://github.com/reb-felipe/eventcounter.git
   cd eventcounter

2. Start RabbitMQ environment

   make env-up

3. Generate test data

   make generator-publish

4. Run the event counter

   go run cmd/consumer/main.go

Usage

The consumer accepts the following flags:

• --amqp-url: RabbitMQ connection URL (default: amqp://guest:guest@localhost:5672/)
• --amqp-exchange: Exchange name (default: eventcountertest)

Example:

go run cmd/consumer/main.go --amqp-url="amqp://user:pass@localhost:5672/" --amqp-exchange="events"

Output

The system generates JSON files in the ./output directory, organized by event type:

output/
├── created_events.json
├── updated_events.json
└── deleted_events.json

Each file contains user event counts:

{
  "user-123": 15,
  "user-456": 8,
  "user-789": 23
}

🧪 Development

Environment Management

• Start environment: make env-up
• Stop environment: make env-down
• Generate test messages: make generator-publish

Configuration

Modify the first lines of the Makefile to customize RabbitMQ port and exchange settings.

📁 Project Structure

├── cmd/
│   ├── consumer/          # Main consumer application
│   └── generator/         # Test message generator
├── pkg/                   # Shared packages and interfaces
├── Makefile              # Development commands
└── README.md