Task Runner

A simple Go project to demonstrate robust error handling patterns including:

• ✅ Sentinel errors
• 🔄 Error wrapping with %w
• 🧩 Custom error types
• ⏳ Context-based timeouts
• 🔍 Error inspection with errors.Is and errors.As

Overview

The taskrunner simulates a basic task execution system. It reads a list of tasks from a JSON file, validates them, and processes each task within a deadline. This project is designed as a practical guide to idiomatic error handling in Go.

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Project Structure

taskrunner/
├── go.mod
├── main.go
├── README.md
├── taskrunner
│   ├── processor.go
│   ├── reader.go
│   └── task.go
└── tasks.json

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Getting Started

Prerequisites

• Go 1.18 or higher installed

Clone & Run

git clone https://github.com/0mynk/task_processor
cd task_processor
go mod tidy  #optional
go run main.go

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Sample Input: tasks.json

[
    { "id": "task1", "value": 42 },
    { "id": "task2", "value": -5 },
    { "id": "task3", "value": 13 },
    { "id": "task4", "value": 42 },
    { "id": "task5", "value": 3 },
    { "id": "task6", "value": 1 },
    { "id": "task7", "value": 2 },
    { "id": "task8", "value": 22 }
]

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What You'll Learn

Feature	Description
Sentinel Errors	Reusable, predefined error values like ErrFileNotFound, checked with errors.Is
Error Wrapping	Use %w in fmt.Errorf to preserve and trace error origins
Custom Error Types	Struct-based errors (ErrInvalidTask) to carry task-specific info
Context Cancellation	Timeout each task using context.WithTimeout
Error Unwrapping	Detect specific error types with errors.As and errors.Is

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Example Output

Task "task1" timed out
Skipping invalid task "task2": negative value
Task "task3" timed out
Task "task4" timed out
Task "task5" completed successfully
Task "task6" completed successfully
Task "task7" completed successfully
Task "task8" timed out

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💡 Extend This Project

• Add unit tests with the testing package
• Implement concurrency with goroutines and channels
• Add retries or backoff mechanisms
• Log errors using a structured logger like zap or logrus

License

MIT License — free to use, modify, and share.

Author

Crafted as a learning tool for mastering Go's error handling. Feel free to fork, star, or open a pull request!