org.apache.lucene.store.jdbc.index.FetchOnOpenJdbcIndexInput.java Source code

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Here is the source code for org.apache.lucene.store.jdbc.index.FetchOnOpenJdbcIndexInput.java

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/*
 * Copyright 2004-2009 the original author or authors.
 *
 * Licensed 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.lucene.store.jdbc.index;

import java.io.IOException;
import java.sql.Blob;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.jdbc.JdbcDirectory;
import org.apache.lucene.store.jdbc.JdbcFileEntrySettings;
import org.apache.lucene.store.jdbc.JdbcStoreException;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.PreparedStatementCallback;

/**
 * An <code>IndexInput</code> implementation that will read all the relevant data from the
 * database when created, and will cache it untill it is closed.
 * <p/>
 * Used for small file entries in the database like the segments file.
 *
 * @author kimchy
 */
public class FetchOnOpenJdbcIndexInput extends IndexInput implements JdbcIndexConfigurable {

    //There is no synchronizaiton since Lucene RAMDirecoty performs no synchronizations.
    // Need to get to the bottom of it.

    private long length;

    private long position = 0;

    private byte[] data;

    /**
     * resourceDescription should be a non-null, opaque string
     * describing this resource; it's returned from
     * {@link #toString}.
     *
     * @param resourceDescription
     */
    protected FetchOnOpenJdbcIndexInput(String resourceDescription) {
        super(resourceDescription);
    }

    public void configure(final String name, final JdbcDirectory jdbcDirectory, JdbcFileEntrySettings settings)
            throws IOException {
        jdbcDirectory.getJdbcTemplate().execute(jdbcDirectory.getTable().sqlSelectSizeValueByName(),
                new PreparedStatementCallback<Object>() {
                    @Override
                    public Object doInPreparedStatement(PreparedStatement ps)
                            throws SQLException, DataAccessException {
                        ps.setFetchSize(1);
                        ps.setString(1, name);
                        try (ResultSet rs = ps.executeQuery()) {
                            if (!rs.next()) {
                                throw new JdbcStoreException(
                                        "No entry for [" + name + "] table " + jdbcDirectory.getTable());
                            }
                            length = rs.getInt(3);

                            Blob blob = rs.getBlob(2);
                            data = blob.getBytes(1, (int) length);
                            if (data.length != length) {
                                throw new IOException("read past EOF");
                            }

                        } catch (JdbcStoreException e) {
                            e.printStackTrace();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        return null;
                    }
                });
    }

    public byte readByte() throws IOException {
        return data[((int) position++)];
    }

    public void readBytes(byte[] b, int offset, int len) throws IOException {
        System.arraycopy(data, (int) position, b, offset, len);
        position += len;
    }

    public void close() throws IOException {

    }

    public long getFilePointer() {
        return position;
    }

    public void seek(long pos) throws IOException {
        position = (int) pos;
    }

    public long length() {
        return this.length;
    }

    @Override
    public IndexInput slice(String sliceDescription, long offset, long length) throws IOException {
        FetchOnOpenJdbcIndexInput index = new FetchOnOpenJdbcIndexInput(sliceDescription);
        index.data = this.data;
        index.position = offset;
        index.length = length;
        return null;
    }
}