Quadcap Embeddable Database

com/quadcap/sql/file/FileRandomAccess.java

Go to the documentation of this file.

package com.quadcap.sql.file;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

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

/**
 * 
 *
 * @author Stan Bailes
 */
public class FileRandomAccess extends RandomAccess {
    long                        pos;
    long                        maxSize;
    RandomAccessFile            ra;

    public FileRandomAccess(RandomAccessFile ra, long maxSize) {
        this.maxSize = maxSize;
        this.ra = ra;
    }

    /**
     * Return the size of the managed region.
     */
    public long size() {
        try {
            return ra.length();
        } catch (IOException ex) {
            return -1;
        }
    }

    /**
     * Resize the managed region.
     */
    public void resize(long newSize) throws IOException {
        ra.setLength(newSize);
    }

    /* Write <tt>len</tt> bytes from position <tt>offset</tt> in buffer
     * <tt>buf</tt> to position <tt>pos</tt> bytes into the managed
     * area.
     */
    public void write(long p, byte[] b, int offset, int len)
        throws IOException
    {
        checkCapacity(p+len);
        if (p != pos) {
            ra.seek(p);
            pos = p;
        }
        ra.write(b, offset, len);
        pos += len;
    }

    /**
     * Read <tt>len</tt> bytes from location <tt>pos</tt> of the region
     * into the buffer <tt>buf</tt>, starting at <tt>offset</tt>.
     */
    public void read(long p, byte[] b, int offset, int len)
        throws IOException
    {
        if (p != pos) {
            ra.seek(p);
            pos = p;
        }
        ra.read(b, offset, len);
        pos += len;
    }

    /**
     * Finalization...
     */
    public void close() throws IOException {
        ra.close();
    }

    public void flush() throws IOException {
        try {
            ra.getFD().sync();
        } catch (Throwable t) {
        }
    }

    final void checkCapacity(long t) throws IOException {
        if (t > ra.length()) {
            if (t > maxSize) {
                throw new IOException("full");
            }
            try {
                ra.setLength(t);
            } catch (IOException e) {
                if (e.toString().indexOf("extended attributes") > 0) {
                    return;
                }
                throw e;
            }
        }
    }
}