Pre-populate Cache

Original issue created by richarddowsett on 2011-10-27 at 12:14 PM

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Pre-populating a cache is a common use case for loading static data from a database. This would also be specifically useful where lazy loading is not ideal. Please see http://stackoverflow.com/questions/7915016/pre-load-values-for-a-guava-cache for a specific case where this would be useful.

It would be ideal to create an interface that can pre-load all static data from the database and add it to the Cache at start-up, such as:

CacheBuilder.newBuilder().populate(new CachePopulator<String, Element>(){

@Override
public Map<String, Element> populate() throws Exception {
    return getAllElements();
}

}).build(new CacheLoader<String, Element>(){

@Override
public Element load(String key) throws Exception {       
    return getElement(key);
}

});

[Normal]

but what if I need the data be populated repeatedly on eviction time is over? PutAll doesn’t handle that. Isn’t it?

[gissuebot]

Original comment posted by richarddowsett on 2011-10-28 at 12:07 PM

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I’m assuming this would be the interface for the new feature (or something similar): Cache.getAll(List<K> keys).

As Raymond has pointed out, this would result in keys.size() calls to the database where my solution would allow you to get all values in a single DAO call. This would surely be a better solution where the cache needs to be pre-populated with a large number of elements.