I would like to cache the following data entity map object for each userId.
/**
* Example data object
*/
data class Data(
val id: Int,
val name: String,
val age: Int
)
As one of the ideas, I considered the following cache in Caffeine.
/**
* Ex.1 cache
* userId to (dataId to Data)
*/
val userDataCache = Caffeine.newBuilder()
.build<Int, ConcurrentHashMap<Int, Data>>()
/**
* invalidate by userId
*/
fun invalidate(userId: Int) {
userDataCache.invalidate(userId)
}
However, the userDataCache in the above example is not thread-safe because it is defined as a nested hashmap.
I've prepared another idea to make it thread-safe.
/**
* Ex.2 cache
* Pair(userId, dataId) to Data
*/
val userDataCache = Caffeine.newBuilder()
.build<Pair<Int, Int>, Data>()
/**
* invalidate by userId
*/
fun invalidate(userId: Int) {
TODO("No idea !!!")
}
This method is thread-safe because it does not use a nested hashmap.
However, this method does not allow us to define an invalidate method to invalidate the cache for each userId.
How can I use Caffeine Cache or ConcurrentHashMap in a way that satisfies the following requirements?
- Cache the data map per userId
- Invalidate the data map per userId
- Make it thread-safe
