🚀 Kvotis — KEY-VALUE CACHE

A high-performance, in-memory Key-Value cache built with Node.js & TypeScript, supporting multiple eviction policies, lazy TTL expiration, and Redis-inspired persistence (AOF & AOF Rewrite).
Designed to explore core cache internals and system design fundamentals.

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📑 Table of Contents

• 📑 Table of Contents
• ⭐ Features
• 🔮 Future Additions
• 🛠 Tech Stack
• 🧩 Architecture Overview
• 🧠 Eviction Policies
  • 1️⃣ LRU — Least Recently Used
  • 2️⃣ LFU — Least Frequently Used
  • 3️⃣ FIFO — First In First Out
  • 4️⃣ NONE — No Eviction
• ⏱ TTL (Time-To-Live)
  • ✔ How It Works
  • ✔ Behavior
• 💾 Persistence
  • 1️⃣ Append-Only File (AOF)
  • 2️⃣ AOF Rewrite (Compaction)
• Setup And Installation
• 🧭 Roadmap
• 📄 License
• 🤝 Contributing
• ⭐ Show Your Support

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⭐ Features

✔ In-memory Key-Value store
✔ Configurable memory limit (bytes-based)
✔ Multiple eviction policies
✔ Lazy TTL expiration
✔ Append-Only File (AOF) persistence
✔ AOF Rewrite (compaction)
✔ Modular, pluggable architecture
✔ Dockerized for local testing

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🔮 Future Additions

• Active TTL expiration (background cleaner)
• Snapshot-based persistence
• Replication support
• Sharding & partitioning
• Metrics & observability
• Networked cache protocol (Redis-like)

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🛠 Tech Stack

Node.js • TypeScript • Docker

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🧩 Architecture Overview

• Core storage uses an in-memory Map
• Eviction & persistence are pluggable components
• TTL is enforced on access (lazy expiration)

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🧠 Eviction Policies

Kvotis supports multiple eviction strategies, configurable at runtime.

1️⃣ LRU — Least Recently Used

• Evicts the key that has not been accessed recently
• Updated on every GET and SET
• Commonly used in production caches

2️⃣ LFU — Least Frequently Used

• Evicts the key with the lowest access frequency
• Suitable for workloads with hot keys

3️⃣ FIFO — First In First Out

• Evicts keys in insertion order
• Simple and predictable

4️⃣ NONE — No Eviction

• Cache throws OOM error when memory limit is reached
• Useful for testing and strict memory enforcement

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⏱ TTL (Time-To-Live)

Kvotis uses lazy TTL expiration.

✔ How It Works

• Each key can have an optional TTL
• Expiration timestamp is stored with the value
• TTL is checked only on access (GET)

✔ Behavior

• Expired keys are removed when accessed
• Prevents unnecessary background CPU usage
• Ensures correctness without active scanning

This mirrors Redis’s lazy expiration strategy (partial implementation).

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💾 Persistence

Kvotis implements Redis-inspired persistence mechanisms.

1️⃣ Append-Only File (AOF)

• Every mutating operation (SET, DELETE) is appended to a log
• On restart, cache state is reconstructed by replaying the log
• Guarantees durability of writes

2️⃣ AOF Rewrite (Compaction)

• Periodically rewrites the AOF file
• Removes redundant commands
• Keeps only the minimal command set to rebuild current state
• Prevents unbounded AOF growth

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Setup And Installation

Clone the repository

git clone https://github.com/Anshikakalpana/kvotis

Build & run

docker compose up --build

npm run start

🧭 Roadmap

• Active TTL expiration

• Snapshot persistence

• Replication

• Metrics endpoint

• Network protocol support

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📄 License

MIT License — free for personal & commercial use.

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🤝 Contributing

Contributions, issues, and feature requests are welcome!
Feel free to check the issues page.

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⭐ Show Your Support

Give a ⭐️ if this project helped you!

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Made with ❤️ by Anshika Kalpana