Cache modes and database persistence

Follow data flow, not preset names

Strategy	Read miss	Write	Consistency owner
Cache-aside	Application reads DB and fills cache	Application updates DB and cache	Application service
Read-through	MapLoader reads DB	Separate policy	Loader and cache configuration
Write-through	Cache write waits for MapWriter DB write	Synchronous DB persistence	Writer failure reaches caller
Write-behind	Queue persists after cache write	Asynchronous batched persistence	Backlog, retry, and shutdown drain

Calling repository code after RMap.put() is cache-aside. Calling it write-through hides its actual transaction and failure boundary.

What RedissonCacheConfig does

RedissonCacheConfig groups cache mode, Redisson WriteMode, retry, and local-cache options. Its conversion functions transfer write options but do not create a loader or writer.

val config = RedissonCacheConfig.WRITE_BEHIND.copy(
    writeBehindBatchSize = 100,
    writeBehindDelay = 500,
)

val options = config.toMapOptions<String, User>("users")
    .loader(userLoader)
    .writer(userWriter)

val users = client.getMap(options)

The database repository supplies the actual MapLoader and MapWriter. The loader handles misses; the writer implements database writes and deletes with an explicit transaction boundary.

Unsupported settings fail fast

The 1.11.0 conversion cannot directly apply ttl, maxSize, or deleteFromDBOnInvalidate. Non-default values fail with IllegalArgumentException instead of being ignored.

• Use RMapCache entry expiration for TTL.
• Use nearCacheMaxSize, nearCacheTtl, and nearCacheMaxIdleTime for local bounds.
• Implement delete-on-invalidate in the application or repository layer.

Write-behind operations

Write-behind reduces request-side persistence time by giving up immediate database freshness. A process crash, Redis outage, or writer failure can leave delayed or lost writes.

Before choosing it, define key ordering and coalescing, idempotent retries, backlog and oldest-age metrics, shutdown drain timeout, and a repair path for records present in cache but absent from the database.

Continue into Exposed and workshops

bluetape4k-exposed provides the common JdbcCacheRepository contract plus the Redisson-specific AbstractJdbcRedissonRepository, ExposedEntityMapLoader, and ExposedEntityMapWriter. Chapter 11 cache-strategy examples in Exposed Workshop connect that boundary to RMap or RLocalCachedMap and Exposed tables. Use this implementation to learn read/write-through; do not treat a plain put example as canonical persistence.

Source and tests

• RedissonCacheConfig.kt
• MapCacheSupport.kt
• RedissonCacheConfigTest.kt
• bluetape4k-exposed
• Exposed Workshop