Solving the ABA Problem in Rust with Hazard Pointers

• Introduction
• 📺 Series Overview
• 🔍 What Are Hazard Pointers?
• 🛡️ How Hazard Pointers Work
• ⚙️ Implementation in Rust
• 🧪 Testing the Implementation
• 🏢 Practical Applications
• 1. Database Systems
• 2. Network Packet Processing
• 3. Task Scheduling Systems
• 4. Real-world Examples
• 🔒 Safety Considerations
• ⚖️ Comparison with Arc
• ⚠️ Common Pitfalls
• 1. Missing Validation Step
• 2. Memory Ordering Bugs
• 3. Resource Leaks
• 4. Debugging Tips
• 🔗 Resources
• 🤔 Final Thoughts

Introduction

In our journey exploring solutions to the ABA problem in Rust, we’ve covered tagged pointers and epoch-based reclamation. In this third and final post of the series, we’ll examine hazard pointers — a technique that provides fine-grained protection for individual memory locations.

📺 Series Overview

This is the final post in our three-part series on solving the ABA problem in Rust:

1. ✅ Part 1: Tagged Pointers with Versioning — We covered how to pair pointers with version numbers
2. ✅ Part 2: Epoch-Based Reclamation — We explored using epochs for safe memory reclamation
3. 🎯 Part 3: Hazard Pointers — Today’s post on using hazard pointers for precise memory protection

🔍 What Are Hazard Pointers?

Hazard pointers are a memory reclamation technique that protects specific memory addresses from being recycled while they’re in use. Unlike epoch-based reclamation, which protects all shared memory during an epoch, hazard pointers protect only explicitly marked locations.

Key concepts:

• Pointer Registration: Threads explicitly register pointers they’re currently using
• Per-Thread Protection: Each thread maintains its own list of hazard pointers
• Selective Reclamation: Memory is only reclaimed when no thread has registered it as hazardous
• Retirement Queue: Memory scheduled for deletion is first moved to a retirement queue

Read the full blog post here:
https://minikin.me/blog/solving-the-aba-problem-in-rust-hazard-pointers