Caffeine Cache: Algorithm Advantages, Usage Strategies, and Spring Boot Integration

Introduces Caffeine Cache, a high‑performance local cache library that improves upon Guava Cache by using the modern W‑TinyLFU eviction algorithm.

Algorithm advantages – W‑TinyLFU

Explains FIFO, LRU, LFU limitations and how W‑TinyLFU combines LFU’s high hit rate with LRU’s handling of burst traffic, using Count‑Min Sketch and a sliding‑window reset to keep frequency information lightweight.

Usage

Shows three loading strategies: manual loading with cache.get(key, k->...) , synchronous loading via LoadingCache with a CacheLoader , and asynchronous loading with AsyncLoadingCache and CompletableFuture .

Eviction policies

Describes size‑based, time‑based and reference‑based eviction, including .maximumSize() , .expireAfterWrite() , .expireAfterAccess() , .weakKeys() , .softValues() , and the incompatibilities between some options.

Removal listener and CacheWriter

Provides examples of .removalListener((key, value, cause) -> System.out.printf("Key %s was removed (%s)%n", key, cause)) and .writer(new CacheWriter () { public void write(String key, Object value) { /* write to external store */ } public void delete(String key, Object value, RemovalCause cause) { /* delete from external store */ } }) for custom actions on eviction or persistence.

Statistics

Enables .recordStats() and shows how to retrieve hit rate, eviction count, and average load penalty from CacheStats .

Spring Boot integration

Explains that Spring Boot 2.x replaces Guava with Caffeine as the default local cache, shows Maven dependencies, the @EnableCaching annotation, configuration via application.properties or YAML, and a CacheLoader bean for refreshAfterWrite .

Cache annotations

Details @Cacheable , @CachePut , @CacheEvict , @Caching , and @CacheConfig , including SpEL key expressions, condition/unless clauses, and the sync option for synchronized cache population.

Provides a complete example service class using these annotations and a programmatic SimpleCacheManager with multiple CaffeineCache beans:

public class UserCacheService {
    @Cacheable(value = "userCache", key = "#id", sync = true)
    public void getUser(long id) { /* query DB */ }

    @CachePut(value = "userCache", key = "#user.id")
    public void saveUser(User user) { /* save DB */ }

    @CacheEvict(value = "userCache", key = "#user.id")
    public void delUser(User user) { /* delete DB */ }
}

Also shows how to create a SimpleCacheManager bean that registers several CaffeineCache instances with custom TTL and maximum size.