@Override
public List<RecommendedItem> recommend(
long userID, int howMany, IDRescorer rescorer, boolean includeKnownItems)
throws TasteException {
Preconditions.checkArgument(howMany >= 1, "howMany must be at least 1");
synchronized (maxHowMany) {
if (howMany > maxHowMany[0]) {
maxHowMany[0] = howMany;
}
}
// Special case, avoid caching an anonymous user
if (userID == PlusAnonymousUserDataModel.TEMP_USER_ID) {
return recommendationsRetriever.get(PlusAnonymousUserDataModel.TEMP_USER_ID).getItems();
}
setCurrentRescorer(rescorer);
setCurrentlyIncludeKnownItems(includeKnownItems);
Recommendations recommendations = recommendationCache.get(userID);
if (recommendations.getItems().size() < howMany
&& !recommendations.isNoMoreRecommendableItems()) {
clear(userID);
recommendations = recommendationCache.get(userID);
if (recommendations.getItems().size() < howMany) {
recommendations.setNoMoreRecommendableItems(true);
}
}
List<RecommendedItem> recommendedItems = recommendations.getItems();
return recommendedItems.size() > howMany
? recommendedItems.subList(0, howMany)
: recommendedItems;
}
/**
* Clears cached recommendations for the given user.
*
* @param userID clear cached data associated with this user ID
*/
public void clear(final long userID) {
log.debug("Clearing recommendations for user ID '{}'", userID);
recommendationCache.remove(userID);
estimatedPrefCache.removeKeysMatching(
new Cache.MatchPredicate<LongPair>() {
@Override
public boolean matches(LongPair userItemPair) {
return userItemPair.getFirst() == userID;
}
});
}
@Override
public void refresh(Collection<Refreshable> alreadyRefreshed) {
neighborhoodCache.clear();
alreadyRefreshed = RefreshHelper.buildRefreshed(alreadyRefreshed);
RefreshHelper.maybeRefresh(alreadyRefreshed, neighborhood);
}
@Override
public long[] getUserNeighborhood(long userID) throws TasteException {
return neighborhoodCache.get(userID);
}
/** Clears all cached recommendations. */
public void clear() {
log.debug("Clearing all recommendations...");
recommendationCache.clear();
estimatedPrefCache.clear();
}
@Override
public float estimatePreference(long userID, long itemID) throws TasteException {
return estimatedPrefCache.get(new LongPair(userID, itemID));
}