Implementing a Two‑Level Cache System with Guava and Redis in Java

Cache is one of the most direct ways to improve system performance, and mastering its use is a fundamental skill for developers.

1. Generic Cache Interface

The article defines a common cache provider interface with methods for getting, setting, removing, and checking cache entries, supporting overloads with functional callbacks and custom expiration times.

1.1 Cache Algorithms

Common eviction policies such as FIFO, LFU, and LRU are introduced.

1.2 Interface Definition

A Java interface CacheProviderService is presented, outlining generic methods for cache operations.

2. Local Cache (Guava)

Guava Cache is used for in‑process caching. The article shows how to add the Guava dependency, configure a CacheBuilder with maximum size and expiration policies, and implement the interface in LocalCacheProviderImpl .

2.1 Implementation Highlights

The implementation handles cache retrieval with optional functions, expiration handling, and thread‑safe creation of cache containers.

3. Distributed Cache (Redis)

Redis is introduced as a widely used distributed cache. Dependencies for Spring Boot are added, and a RedisConfig class configures the connection factory, cache manager, and serialization strategies.

3.1 Redis Provider Implementation

The RedisCacheProviderImpl class implements the same cache interface using RedisTemplate and ValueOperations , supporting custom expiration and functional callbacks.

4. Cache Expiration and Versioning

Real‑time cache expiration challenges are discussed, and a version‑based key strategy is proposed to invalidate caches across nodes.

5. Two‑Level Cache Builder

A PowerCacheBuilder class orchestrates multiple cache providers, preferring local cache first and falling back to Redis. It includes methods to generate versioned keys, reset cache versions, and perform get/set/remove operations across all providers.

5.1 Usage Example

Sample unit test demonstrates obtaining a cache version, generating a versioned key, storing an object, retrieving it, and resetting the version to invalidate stale entries.

Overall, the article provides a complete guide to building a robust two‑level caching system in Java, suitable for Spring Boot applications.