Cache strategies and ecosystem paths

Follow the data path

Strategy	Miss/write owner	Source-store call
Cache-aside	Caller	Caller reads and writes the source directly
Read-through	CacheLoader/MapLoader	A cache miss invokes the loader
Write-through	CacheWriter/MapWriter	A cache write invokes the writer before success
Write-behind	Writer queue	The source is updated asynchronously after the cache

RedissonNearCache.put() and memoizer RMap.putIfAbsent() update Redis cache state. Without a writer that calls the database, neither is persistence write-through.

Cache-aside baseline

suspend fun findProduct(id: String): Product {
    products.get(id)?.let { return it }
    return repository.findById(id).also { loaded ->
        products.put(id, loaded)
    }
}

The first request reads the database and fills the cache. Updates still need a documented commit-versus-invalidation order and a stale-window policy.

Real loader and writer examples

examples/redisson-demo uses MapLoader, MapWriter, and async variants for read-through, write-through, and write-behind. These examples call an actual repository and therefore differ from cache-aside.

Write-behind can reduce response latency but introduces crash, queue overflow, ordering, and retry risks. Verify durability before making it the only path to the source of truth.

Continue through the ecosystem

• cache-core: local providers, JCache, memoizers, and common near-cache contracts.
• redisson: codecs, distributed maps, locks, topics, and coroutine bridges.
• Hibernate: entity lifecycle and second-level-cache boundaries.
• Spring Boot Hibernate Lettuce: Spring/Hibernate cache wiring.
• redisson-demo: runnable loader/writer strategies.

The exposed-workshop cache chapter connects JdbcCacheRepository, EntityMapLoader, and EntityMapWriter. bluetape4k-workshop continues with service-level examples. Judge strategy names by the actual loader/writer path when examples differ.

Source and tests

• CacheReadThroughExample.kt
• CacheWriteThroughExample.kt
• CacheWriteBehindExample.kt
• MapReadWriteThroughTest.kt