Redis Caching

1. @EnableCaching To enable the caching api of spring boot.
2. @Cacheable Read from cache or compute and store.
3. @CachePut Always execute method, update cache.
4. @CacheEvict Remove cache entry.
5. @Caching Combine multiple cache operations together.

Default

• ConcurrentMapCacheManager: Backed by ConcurrentHashMap.
• JVM memory only, good for local build.

Im-Memory

• Caffeine / EhCache, still in process but muc smarter.

spring:
  cache:
    type: caffeine

@Bean
public CaffeineCacheManager cacheManager() {
    CaffeineCacheManager manager = new CaffeineCacheManager("users");
    manager.setCaffeine(
            Caffeine.newBuilder()
                    .expireAfterWrite(10, TimeUnit.MINUTES)
                    .maximumSize(10_000)
    );
    return manager;
}

• Provides ttl, eviction policies.

Redis (Distributed)

• Redis is external, shared, and persistent.
• Microservices, multiple app instances.

Resilience4J

Circuit Breaker

  Prevents cascading failures when a dependency keeps failing.

States:

1. CLOSED → calls allowed
2. OPEN → calls blocked, fallback triggered
3. HALF_OPEN → limited test calls

Retry

  Handles temporary failures (timeouts, network glitches).

Bulkhead

  Stops resource starvation by isolating calls.

Rate Limiter

  Protects services from traffic spikes or abuse.