name.martingeisse.stackd.server.section.storage.CassandraSectionStorage.java Source code

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Here is the source code for name.martingeisse.stackd.server.section.storage.CassandraSectionStorage.java

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/**
 * Copyright (c) 2010 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.stackd.server.section.storage;

import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import name.martingeisse.stackd.common.geometry.ClusterSize;
import name.martingeisse.stackd.common.network.SectionDataId;
import org.apache.commons.lang3.StringUtils;
import org.apache.log4j.Logger;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Row;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.querybuilder.Clause;
import com.datastax.driver.core.querybuilder.QueryBuilder;

/**
 * This storage implementation stores sections in a Cassandra database.
 */
public final class CassandraSectionStorage extends AbstractSectionStorage {

    /**
     * the logger
     */
    private static Logger logger = Logger.getLogger(CassandraSectionStorage.class);

    /**
     * the cassandrasSession
     */
    private Session cassandrasSession;

    /**
     * the tableName
     */
    private String tableName;

    /**
     * Constructor.
     * @param clusterSize the cluster-size of sections
     * @param cassandrasSession the cassandra {@link Session} object used to access the database
     * @param tableName the name of the section table
     */
    public CassandraSectionStorage(final ClusterSize clusterSize, final Session cassandrasSession,
            final String tableName) {
        super(clusterSize);
        this.cassandrasSession = cassandrasSession;
        this.tableName = tableName;
    }

    /**
     * Getter method for the cassandrasSession.
     * @return the cassandrasSession
     */
    public Session getCassandrasSession() {
        return cassandrasSession;
    }

    /**
     * Getter method for the tableName.
     * @return the tableName
     */
    public String getTableName() {
        return tableName;
    }

    /**
     * 
     */
    private ResultSet fetch(final Clause clause) {
        return cassandrasSession.execute(QueryBuilder.select().all().from(tableName).where(clause));
    }

    /* (non-Javadoc)
     * @see name.martingeisse.stackd.server.section.storage.AbstractSectionStorage#loadSectionRelatedObject(name.martingeisse.stackd.common.network.SectionDataId)
     */
    @Override
    public byte[] loadSectionRelatedObject(final SectionDataId id) {
        try {
            for (final Row row : fetch(QueryBuilder.eq("id", id.getIdentifierText()))) {
                final ByteBuffer dataBuffer = row.getBytes("data");
                final byte[] data = new byte[dataBuffer.remaining()];
                dataBuffer.get(data);
                return data;
            }
            return null;
        } catch (final Exception e) {
            throw new RuntimeException(e);
        }
    }

    /* (non-Javadoc)
     * @see name.martingeisse.stackd.server.section.storage.AbstractSectionStorage#loadSectionRelatedObjects(java.util.Collection)
     */
    @Override
    public Map<SectionDataId, byte[]> loadSectionRelatedObjects(final Collection<? extends SectionDataId> ids) {
        if (logger.isDebugEnabled()) {
            logger.debug("loading section-related objects: " + StringUtils.join(ids, ", "));
        }
        try {

            // convert the IDs to an array of strings
            Object[] idTexts = new String[ids.size()];
            {
                int i = 0;
                for (SectionDataId id : ids) {
                    idTexts[i] = id.getIdentifierText();
                    i++;
                }
            }

            // fetch the rows
            final Map<SectionDataId, byte[]> result = new HashMap<>();
            for (final Row row : fetch(QueryBuilder.in("id", idTexts))) {
                final String id = row.getString("id");
                final ByteBuffer dataBuffer = row.getBytes("data");
                final byte[] data = new byte[dataBuffer.remaining()];
                dataBuffer.get(data);
                result.put(new SectionDataId(id), data);
            }
            return result;

        } catch (final Exception e) {
            throw new RuntimeException(e);
        }
    }

    /* (non-Javadoc)
     * @see name.martingeisse.stackd.server.section.storage.AbstractSectionStorage#saveSectionRelatedObject(name.martingeisse.stackd.common.network.SectionDataId, byte[])
     */
    @Override
    public void saveSectionRelatedObject(final SectionDataId sectionDataId, final byte[] data) {
        try {
            final String rowId = sectionDataId.getIdentifierText();
            cassandrasSession.execute(
                    QueryBuilder.insertInto(tableName).value("id", rowId).value("data", ByteBuffer.wrap(data)));
        } catch (final Exception e) {
            throw new RuntimeException(e);
        }
    }

    /* (non-Javadoc)
     * @see name.martingeisse.stackd.server.section.storage.AbstractSectionStorage#deleteSectionRelatedObject(name.martingeisse.stackd.common.network.SectionDataId)
     */
    @Override
    public void deleteSectionRelatedObject(final SectionDataId sectionDataId) {
        try {
            final Clause clause = QueryBuilder.eq("id", sectionDataId.getIdentifierText());
            cassandrasSession.execute(QueryBuilder.delete().from(tableName).where(clause));
        } catch (final Exception e) {
            throw new RuntimeException(e);
        }
    }

}