HSQLDB example source code file (RAShadowFile.java)

This example HSQLDB source code file (RAShadowFile.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - HSQLDB tags/keywords

bitmap, bitmap, database, hsqlbytearrayoutputstream, io, ioexception, ioexception, randomaccessfile, randomaccessfile, rashadowfile, storage, string, string, throwable

The HSQLDB RAShadowFile.java source code

/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


package org.hsqldb.persist;

import java.io.IOException;
import java.io.RandomAccessFile;

import org.hsqldb.Database;
import org.hsqldb.lib.FileUtil;
import org.hsqldb.lib.SimpleLog;
import org.hsqldb.lib.Storage;
import org.hsqldb.lib.java.JavaSystem;
import org.hsqldb.store.BitMap;
import org.hsqldb.lib.HsqlByteArrayOutputStream;

/*
 * Wrapper for random access file for incremental backup of the .data file.
 *
 * @author Fred Toussi (fredt@users dot sourceforge.net)
 * @version 1.9.0
 * @since 1.9.0
 */
public class RAShadowFile {

    final Database   database;
    final String     pathName;
    final Storage    source;
    RandomAccessFile dest;
    final int        pageSize;
    final long       maxSize;
    final BitMap     bitMap;
    boolean          zeroPageSet;
    HsqlByteArrayOutputStream byteArrayOutputStream =
        new HsqlByteArrayOutputStream(new byte[]{});

    RAShadowFile(Database database, Storage source, String pathName,
                 long maxSize, int pageSize) {

        this.database = database;
        this.pathName = pathName;
        this.source   = source;
        this.pageSize = pageSize;
        this.maxSize  = maxSize;

        int bitSize = (int) (maxSize / pageSize);

        if (maxSize % pageSize != 0) {
            bitSize++;
        }

        bitMap = new BitMap(bitSize);
    }

    void copy(long fileOffset, int size) throws IOException {

        // always copy the first page
        if (!zeroPageSet) {
            copy(0);
            bitMap.set(0);

            zeroPageSet = true;
        }

        if (fileOffset >= maxSize) {
            return;
        }

        long endOffset       = fileOffset + size;
        int  startPageOffset = (int) (fileOffset / pageSize);
        int  endPageOffset   = (int) (endOffset / pageSize);

        if (endOffset % pageSize == 0) {
            endPageOffset--;
        }

        for (; startPageOffset <= endPageOffset; startPageOffset++) {
            copy(startPageOffset);
        }
    }

    private void copy(int pageOffset) throws IOException {

        if (bitMap.set(pageOffset) == 1) {
            return;
        }

        long position = (long) pageOffset * pageSize;
        int  readSize = pageSize;

        if (maxSize - position < pageSize) {
            readSize = (int) (maxSize - position);
        }

        try {
            if (dest == null) {
                open();
            }

            long   writePos = dest.length();
            byte[] buffer   = new byte[pageSize + 12];

            byteArrayOutputStream.setBuffer(buffer);
            byteArrayOutputStream.writeInt(pageSize);
            byteArrayOutputStream.writeLong(position);
            source.seek(position);
            source.read(buffer, 12, readSize);
            dest.seek(writePos);
            dest.write(buffer, 0, buffer.length);
        } catch (Throwable t) {
            bitMap.unset(pageOffset);
            close();
            database.logger.appLog.logContext(SimpleLog.LOG_ERROR,
                                              "pos" + position + " "
                                              + readSize);

            throw FileUtil.toIOException(t);
        } finally {}
    }

    private void open() throws IOException {
        dest = new RandomAccessFile(pathName, "rws");
    }

    /**
     * Called externally after a series of copy() calls.
     * Called internally after a restore or when error in writing
     */
    void close() throws IOException {

        if (dest != null) {
            dest.getFD().sync();
            dest.close();

            dest = null;
        }
    }

    /** todo - take account of incomplete addition of block due to lack of disk */

    // buggy database files had size == position == 0 at the end
    public static void restoreFile(String sourceName,
                                   String destName) throws IOException {

        RandomAccessFile source = new RandomAccessFile(sourceName, "r");
        RandomAccessFile dest   = new RandomAccessFile(destName, "rw");

        while (source.getFilePointer() != source.length()) {
            int    size     = source.readInt();
            long   position = source.readLong();
            byte[] buffer   = new byte[size];

            source.read(buffer, 0, buffer.length);
            dest.seek(position);
            dest.write(buffer, 0, buffer.length);
        }

        source.close();
        dest.close();
    }
}