@Override
public void setPreference(long userID, long itemID, float value) throws TasteException {
DataModel dataModel = getDataModel();
double prefDelta;
try {
Float oldPref = dataModel.getPreferenceValue(userID, itemID);
prefDelta = oldPref == null ? value : value - oldPref;
} catch (NoSuchUserException nsee) {
prefDelta = value;
}
super.setPreference(userID, itemID, value);
try {
buildAveragesLock.writeLock().lock();
RunningAverage itemAverage = itemAverages.get(itemID);
if (itemAverage == null) {
RunningAverage newItemAverage = new FullRunningAverage();
newItemAverage.addDatum(prefDelta);
itemAverages.put(itemID, newItemAverage);
} else {
itemAverage.changeDatum(prefDelta);
}
RunningAverage userAverage = userAverages.get(userID);
if (userAverage == null) {
RunningAverage newUserAveragae = new FullRunningAverage();
newUserAveragae.addDatum(prefDelta);
userAverages.put(userID, newUserAveragae);
} else {
userAverage.changeDatum(prefDelta);
}
overallAveragePrefValue.changeDatum(prefDelta);
} finally {
buildAveragesLock.writeLock().unlock();
}
}
@Override
public float estimatePreference(long userID, long itemID) throws TasteException {
DataModel dataModel = getDataModel();
Float actualPref = dataModel.getPreferenceValue(userID, itemID);
if (actualPref != null) {
return actualPref;
}
return doEstimatePreference(userID, itemID);
}
@Override
public void removePreference(long userID, long itemID) throws TasteException {
DataModel dataModel = getDataModel();
Float oldPref = dataModel.getPreferenceValue(userID, itemID);
super.removePreference(userID, itemID);
if (oldPref != null) {
try {
buildAveragesLock.writeLock().lock();
RunningAverage itemAverage = itemAverages.get(itemID);
if (itemAverage == null) {
throw new IllegalStateException("No preferences exist for item ID: " + itemID);
}
itemAverage.removeDatum(oldPref);
RunningAverage userAverage = userAverages.get(userID);
if (userAverage == null) {
throw new IllegalStateException("No preferences exist for user ID: " + userID);
}
userAverage.removeDatum(oldPref);
overallAveragePrefValue.removeDatum(oldPref);
} finally {
buildAveragesLock.writeLock().unlock();
}
}
}