/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.cf.taste.impl.model.jdbc;
import com.google.common.base.Preconditions;
import org.apache.mahout.cf.taste.common.Refreshable;
import org.apache.mahout.cf.taste.common.TasteException;
import org.apache.mahout.cf.taste.impl.common.FastIDSet;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveIterator;
import org.apache.mahout.cf.taste.impl.common.RefreshHelper;
import org.apache.mahout.cf.taste.impl.model.GenericBooleanPrefDataModel;
import org.apache.mahout.cf.taste.impl.model.GenericDataModel;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.model.JDBCDataModel;
import org.apache.mahout.cf.taste.model.PreferenceArray;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Collection;
import java.util.concurrent.Callable;
/**
* A {@link DataModel} which loads, and can re-load, data from a JDBC-backed {@link JDBCDataModel} into memory, as a
* {@link GenericDataModel} or {@link GenericBooleanPrefDataModel}. It is intended to provide the speed
* advantage of in-memory representation but be able to update periodically to pull in new data from a database source.
*/
public final class ReloadFromJDBCDataModel implements DataModel {
private static final Logger log = LoggerFactory.getLogger(ReloadFromJDBCDataModel.class);
private DataModel delegateInMemory;
private final JDBCDataModel delegate;
private final RefreshHelper refreshHelper;
public ReloadFromJDBCDataModel(JDBCDataModel delegate) throws TasteException {
Preconditions.checkNotNull(delegate, "Delegate cannot be null");
this.delegate = delegate;
refreshHelper = new RefreshHelper(new Callable<Void>() {
@Override
public Void call() {
reload();
return null; //To change body of implemented methods use File | Settings | File Templates.
}
});
refreshHelper.addDependency(delegate);
reload();
if (delegateInMemory == null) {
throw new TasteException("Failed to load data into memory");
}
}
@Override
public void refresh(Collection<Refreshable> alreadyRefreshed) {
refreshHelper.refresh(alreadyRefreshed);
}
private void reload() {
try {
// Load new in-memory representation,
log.info("Loading new JDBC delegate data...");
DataModel newDelegateInMemory =
delegate.hasPreferenceValues()
? new GenericDataModel(delegate.exportWithPrefs())
: new GenericBooleanPrefDataModel(delegate.exportWithIDsOnly());
// and then swap to it.
log.info("New data loaded.");
delegateInMemory = newDelegateInMemory;
} catch (TasteException te) {
log.warn("Error while reloading JDBC delegate data", te);
// But continue with whatever is loaded
}
}
public JDBCDataModel getDelegate() {
return delegate;
}
public DataModel getDelegateInMemory() {
return delegateInMemory;
}
// Delegated methods:
@Override
public LongPrimitiveIterator getUserIDs() throws TasteException {
return delegateInMemory.getUserIDs();
}
@Override
public PreferenceArray getPreferencesFromUser(long id) throws TasteException {
return delegateInMemory.getPreferencesFromUser(id);
}
@Override
public FastIDSet getItemIDsFromUser(long id) throws TasteException {
return delegateInMemory.getItemIDsFromUser(id);
}
@Override
public Float getPreferenceValue(long userID, long itemID) throws TasteException {
return delegateInMemory.getPreferenceValue(userID, itemID);
}
@Override
public Long getPreferenceTime(long userID, long itemID) throws TasteException {
return delegateInMemory.getPreferenceTime(userID, itemID);
}
@Override
public LongPrimitiveIterator getItemIDs() throws TasteException {
return delegateInMemory.getItemIDs();
}
@Override
public PreferenceArray getPreferencesForItem(long itemID) throws TasteException {
return delegateInMemory.getPreferencesForItem(itemID);
}
@Override
public int getNumItems() throws TasteException {
return delegateInMemory.getNumItems();
}
@Override
public int getNumUsers() throws TasteException {
return delegateInMemory.getNumUsers();
}
@Override
public int getNumUsersWithPreferenceFor(long... itemIDs) throws TasteException {
return delegateInMemory.getNumUsersWithPreferenceFor(itemIDs);
}
@Override
public void setPreference(long userID, long itemID, float value) throws TasteException {
delegateInMemory.setPreference(userID, itemID, value);
}
@Override
public void removePreference(long userID, long itemID) throws TasteException {
delegateInMemory.removePreference(userID, itemID);
}
@Override
public boolean hasPreferenceValues() {
return delegateInMemory.hasPreferenceValues();
}
@Override
public float getMaxPreference() {
return delegateInMemory.getMaxPreference();
}
@Override
public float getMinPreference() {
return delegateInMemory.getMinPreference();
}
}