Some code I did while studying for tech interviews. It should be able to do all cache operations in O(1) time.
Some of this depends on the efficiency of the underlying HashMap data structure, which makes up half of the magic.
Usage:
public static class UserRetriever implements CacheRetriever<Long, User> {
public User retrieve( Long id ) {
// Expensive operation
}
}
public void viewUser( long userId ) {
UserRetriever retriever = new UserRetriever();
Cache<Long,String> cache = new Cache<Long,String>( 50, retriever);
User user = cache.retrieve( userId );
render(user);
}This isn't intended to replace or augment a production data retrieval layer, it's just a thought exercise.