HSQLDB example source code file (ScaledRAFileNIO.java)

This example HSQLDB source code file (ScaledRAFileNIO.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

illegalargumentexception, io, ioexception, ioexception, jvm, jvm_error, jvm_error, nio, nio, randomaccessfile, scaledrafilenio, simplelog, string, throwable, throwable

The HSQLDB ScaledRAFileNIO.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 java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

import org.hsqldb.Database;
import org.hsqldb.Trace;
import org.hsqldb.lib.SimpleLog;

/**
 * New NIO version of ScaledRAFile. This class is used only for storing a CACHED
 * TABLE .data file and cannot be used for TEXT TABLE source files.
 *
 * Due to various issues with java.nio classes, this class will use a mapped
 * channel of fixed size. After reaching this size, the file and channel are
 * closed.
 *
 * @author fredt@users
 * @version  1.8.0.5
 * @since 1.8.0.5
 */
class ScaledRAFileNIO implements ScaledRAInterface {

    private final boolean       readOnly;
    private final long          bufferLength;
    private RandomAccessFile    file;
    private MappedByteBuffer    buffer;
    private FileChannel         channel;
    private boolean             bufferModified;
    private SimpleLog           appLog;
    private final static String JVM_ERROR = "JVM threw unsupported Exception";

    ScaledRAFileNIO(Database database, String name, boolean readOnly,
                    int bufferLength) throws Throwable {

        long fileLength;

        if (bufferLength < 1 << 18) {
            bufferLength = 1 << 18;
        }

        try {
            file = new RandomAccessFile(name, readOnly ? "r"
                                                       : "rw");
        } catch (Throwable e) {
            throw e;
        }

        try {
            fileLength = file.length();
        } catch (Throwable e) {
            file.close();

            throw e;
        }

        if (fileLength > ScaledRAFile.MAX_NIO_LENGTH) {
            file.close();

            throw new IOException("length exceeds nio limit");
        }

        if (bufferLength < fileLength) {
            bufferLength = (int) fileLength;
        }

        bufferLength = newNIOBufferSize(bufferLength);

        if (readOnly) {
            bufferLength = (int) fileLength;
        }

        if (fileLength < bufferLength) {
            try {
                file.seek(bufferLength - 1);
                file.writeByte(0);
                file.getFD().sync();
                file.close();

                file = new RandomAccessFile(name, readOnly ? "r"
                                                           : "rw");
            } catch (Throwable e) {
                file.close();

                throw e;
            }
        }

        this.appLog       = database.logger.appLog;
        this.readOnly     = readOnly;
        this.bufferLength = bufferLength;
        this.channel      = file.getChannel();

        try {
            buffer = channel.map(readOnly ? FileChannel.MapMode.READ_ONLY
                                          : FileChannel.MapMode.READ_WRITE, 0,
                                          bufferLength);

            Trace.printSystemOut("NIO file instance created. mode: "
                                 + readOnly);

            if (!readOnly) {
                long tempSize = bufferLength - fileLength;

                if (tempSize > 1 << 18) {
                    tempSize = 1 << 18;
                }

                byte[] temp = new byte[(int) tempSize];

                try {
                    long pos = fileLength;

                    for (; pos < bufferLength - tempSize; pos += tempSize) {
                        buffer.position((int) pos);
                        buffer.put(temp, 0, temp.length);
                    }

                    buffer.position((int) pos);
                    buffer.put(temp, 0, (int) (bufferLength - pos));
                    buffer.force();
                } catch (Throwable t) {
                    appLog.logContext(t, JVM_ERROR + " " + "length: "
                                      + bufferLength);
                }

                buffer.position(0);
            }
        } catch (Throwable e) {
            Trace.printSystemOut("NIO constructor failed:  " + bufferLength);

            buffer  = null;
            channel = null;

            file.close();
            System.gc();

            throw e;
        }
    }

    public long length() throws IOException {

        try {
            return file.length();
        } catch (IOException e) {
            appLog.logContext(e, "nio");

            throw e;
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public void seek(long newPos) throws IOException {

        try {
            buffer.position((int) newPos);
        } catch (IllegalArgumentException e) {
            appLog.logContext(e, "nio");

            throw new IOException(e.toString());
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public long getFilePointer() throws IOException {

        try {
            return buffer.position();
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public int read() throws IOException {

        try {
            return buffer.get();
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public void read(byte[] b, int offset, int length) throws IOException {

        try {
            buffer.get(b, offset, length);
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public int readInt() throws IOException {

        try {
            return buffer.getInt();
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public long readLong() throws IOException {

        try {
            return buffer.getLong();
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public void write(byte[] b, int offset, int len) throws IOException {

        try {
            bufferModified = true;

            buffer.put(b, offset, len);
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public void writeInt(int i) throws IOException {

        try {
            bufferModified = true;

            buffer.putInt(i);
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public void writeLong(long i) throws IOException {

        try {
            bufferModified = true;

            buffer.putLong(i);
        } catch (Throwable e) {
            appLog.logContext(e, JVM_ERROR);

            throw new IOException(e.toString());
        }
    }

    public void close() throws IOException {

        try {
            Trace.printSystemOut("NIO close() start - fileLength = "
                                 + bufferLength);

            if (buffer != null && bufferModified) {
                try {
                    buffer.force();
                } catch (Throwable t) {
                    try {
                        buffer.force();
                    } catch (Throwable t1) {
                        appLog.logContext(t, JVM_ERROR + " " + "length: "
                                          + bufferLength);
                    }
                }
            }

            buffer  = null;
            channel = null;

            file.close();
            System.gc();
        } catch (Throwable e) {
            appLog.logContext(e, "length: " + bufferLength);

            throw new IOException(e.toString());
        }
    }

    public boolean isReadOnly() {
        return readOnly;
    }

    public boolean wasNio() {
        return true;
    }

    public boolean canAccess(int length) {
        return buffer.position() + length <= bufferLength;
    }

    public boolean canSeek(long position) {
        return position <= bufferLength;
    }

    public Database getDatabase() {
        return null;
    }

    public void synch() {

        try {
            buffer.force();
        } catch (Throwable t) {}
    }

    static int newNIOBufferSize(int newSize) {

        int bufSize = 0;

        for (int scale = 20; scale < 30; scale++) {
            bufSize = 1 << scale;

            if (bufSize >= newSize) {
                break;
            }
        }

        return bufSize;
    }
}