How to Write High-Quality Code: From Learning to Refactoring

1. Introduction

In daily work many developers complain about code quality, assuming that only their own code is good and everything else is trash that needs to be refactored. Before answering how to write high‑quality code, we must define its standards: readability, extensibility, high cohesion, low coupling, appropriate paradigms, and design principles.

This article does not focus on rule books or best‑practice checklists, because that leads to endless details without real insight. Instead, it emphasizes understanding underlying principles and execution patterns.

2. Learning Good Code

Learning Awareness

Finding and studying the paths forged by predecessors is a shortcut to mastery. As Henry Spencer said, "People who don’t understand Unix will eventually reinvent a poor version of it." Effective learning reduces time and effort compared to trial‑and‑error.

Choosing Role Models

Study successful examples across history, industry, and companies. Critically digest them, recognizing that guidelines have limits and must be adapted to current contexts (e.g., the 80‑character line limit originated from VT100 terminals).

Applying Knowledge

Motivation and clear goals drive perseverance. Tools such as PDCA cycles and SMART principles help turn learning into practice. Real‑world application, such as introducing a message‑queue middleware to decouple system modules, reinforces concepts.

Summary of Learning

Most work problems have existing solutions; personal experimentation is essential.

Experience has boundaries; blindly copying may not fit your context.

Choosing learning goals at the right time is crucial to avoid wasted effort.

3. Imitating Code

Cognitive Traps

Imitation is not mere copy‑paste; it means quickly locating excellent solutions and adapting them. This stage corresponds to the "I don’t know what I don’t know" layer of cognition.

Start with the End

Technology stacks are vast (network, services, storage, etc.). One must decide whether to become a specialist or a generalist, often progressing from a T‑shaped talent to a π‑shaped or comb‑shaped talent.

4. Designing Code

Programming Thinking

Programming thinking consists of decomposition, pattern recognition, abstraction, and algorithm design.

Coding Principles

The core principle is maintainability; performance is secondary in most scenarios. Principles such as Open/Closed, KISS, composition, dependency inversion, and single responsibility stem from this core.

Peeling the Onion

Deep familiarity with code comes from reading and writing massive amounts of code. A concrete example from the RocketMQ project demonstrates file‑warm‑up, page‑cache usage, and why loops of 4 KB and zero‑filling are employed.

Case Study: RocketMQ File Warm‑up

RocketMQ pre‑writes data to mapped files to load them into the page cache, reducing page‑fault overhead. The article explains page‑fault mechanisms, the impact of 4 KB alignment, and why a Thread.sleep(0) call is inserted to create safepoints that allow the GC to run, preventing long GC pauses.

Summary of Design

Focus on human readability and maintainability.

Focus on machine efficiency where it matters.

5. Refactoring

Understanding Refactoring

Refactoring improves code quality and architecture, enhancing extensibility and maintainability. It is a powerful way to accelerate personal growth.

Common Pitfalls

Over‑optimizing performance at the expense of cost‑effectiveness.

Blindly applying design patterns without solving the actual problem.

Key Points

Refactor when business needs demand it.

Beware of under‑estimating implementation difficulty.

Effective refactoring requires clear goals and disciplined process management.

6. Conclusion

The article outlines a rapid learning path for coding skills, emphasizing the importance of cognition, selecting direction, setting role models, applying knowledge, and avoiding common traps. It uses a RocketMQ code example to show how reading others' code can foster deeper understanding, and it concludes with practical refactoring guidance.