recommender.ReloadFromJDBCDataModelCustom.java Source code

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Here is the source code for recommender.ReloadFromJDBCDataModelCustom.java

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/**
 * 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 recommender;

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 class ReloadFromJDBCDataModelCustom implements DataModel {

    private static final Logger log = LoggerFactory.getLogger(ReloadFromJDBCDataModelCustom.class);

    private DataModel delegateInMemory;
    private JDBCDataModel delegate; // delegate is not final as in ReloadFromJDBCDataModel, to allow setPreference(long userID, long itemID)
    private RefreshHelper refreshHelper;

    public ReloadFromJDBCDataModelCustom(JDBCDataModel delegate) throws TasteException {
        this.delegate = Preconditions.checkNotNull(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 itemID) throws TasteException {
        return delegateInMemory.getNumUsersWithPreferenceFor(itemID);
    }

    @Override
    public int getNumUsersWithPreferenceFor(long itemID1, long itemID2) throws TasteException {
        return delegateInMemory.getNumUsersWithPreferenceFor(itemID1, itemID2);
    }

    @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();
    }

}