CacheStorePreprocessor

A CacheStorePreprocessor processes Cacheable objects before persisting them in the store and after they are read from the store.

For example, a preprocessor can encrypt a Cacheable object before it is persisted to the CacheStore and decrypt the persisted value when it is read from the CacheStore.

It takes three parameters T, R and V which are all Cacheable. The preprocessor archives T and transforms it into R which can then be archived by the next preprocessor. Similarly, it unarchives V into a T.

In many cases, R and V can be same. However, a CacheStore performs a final archiving of the object in a RawCacheable object before persisting it. Therefore for the last preprocessor in the chain, V can be RawCacheable while R can be another type.

Examples

An encrypted Preprocessor

data class PlainObject(val plainText: String): Cacheable....
data class EncryptedObject(val cipherText: String): Cacheable...

class SecureStorePreprocessor: CacheStorePreprocessor<PlainObject, EncryptedObject, RawCacheable> {
    override fun archive(obj: PlainObject) {
        return EncryptedObject(cipherText = aes256.encrypt(KEY, obj.plainText))
    }

    override fun unarchive(obj: RawCacheable): Person {
        val encryptedObject = EncryptedObject.deserializeFromPersistence(obj.key, obj.value)
        return Person(plainText = aes256.decrypt(KEY, encryptedObject.cipherText)
    }
}

Functions