/**
 * JDBM LICENSE v1.00
 *
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 2. 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.
 *
 * 3. The name "JDBM" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Cees de Groot.  For written permission,
 *    please contact cg@cdegroot.com.
 *
 * 4. Products derived from this Software may not be called "JDBM"
 *    nor may "JDBM" appear in their names without prior written
 *    permission of Cees de Groot.
 *
 * 5. Due credit should be given to the JDBM Project
 *    (http://jdbm.sourceforge.net/).
 *
 * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED 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
 * CEES DE GROOT OR ANY 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.
 *
 * Copyright 2000 (C) Cees de Groot. All Rights Reserved.
 * Contributions are Copyright (C) 2000 by their associated contributors.
 *
 * $Id: LogicalRowIdManager.java,v 1.3 2005/06/25 23:12:32 doomdark Exp $
 */

package jdbm.recman;


import java.io.IOException;

import jdbm.I18n;


/**
 *  This class manages the linked lists of logical rowid pages.
 */
final class LogicalRowIdManager
{
    // our record recordFile and associated page manager
    private RecordFile recordFile;
    private PageManager pageManager;
    private FreeLogicalRowIdPageManager freeman;


    /**
     *  Creates a log rowid manager using the indicated record recordFile and
     *  page manager
     */
    LogicalRowIdManager( PageManager pageManager ) throws IOException
    {
        this.recordFile = pageManager.getRecordFile();
        this.pageManager = pageManager;
        this.freeman = new FreeLogicalRowIdPageManager( pageManager );
    }


    /**
     *  Creates a new logical rowid pointing to the indicated physical
     *  id
     */
    Location insert( Location loc ) throws IOException
    {
        // check whether there's a free rowid to reuse
        Location retval = freeman.get();
        if ( retval == null )
        {
            // no. This means that we bootstrap things by allocating
            // a new translation page and freeing all the rowids on it.
            long firstPage = pageManager.allocate( Magic.TRANSLATION_PAGE );
            short curOffset = TranslationPage.O_TRANS;
            for ( int i = 0; i < TranslationPage.ELEMS_PER_PAGE; i++ )
            {
                freeman.put( new Location( firstPage, curOffset ) );
                curOffset += PhysicalRowId.SIZE;
            }
            retval = freeman.get();
            if ( retval == null )
            {
                throw new Error( I18n.err( I18n.ERR_545 ) );
            }
        }
        // write the translation.
        update( retval, loc );
        return retval;
    }


    /**
     *  Releases the indicated logical rowid.
     */
    void delete( Location rowid ) throws IOException
    {

        freeman.put( rowid );
    }


    /**
     *  Updates the mapping
     *
     *  @param rowid The logical rowid
     *  @param loc The physical rowid
     */
    void update( Location rowid, Location loc ) throws IOException
    {

        TranslationPage xlatPage = TranslationPage.getTranslationPageView( recordFile.get( rowid.getBlock() ) );
        PhysicalRowId physid = xlatPage.get( rowid.getOffset() );
        physid.setBlock( loc.getBlock() );
        physid.setOffset( loc.getOffset() );
        recordFile.release( rowid.getBlock(), true );
    }


    /**
     *  Returns a mapping
     *
     *  @param rowid The logical rowid
     *  @return The physical rowid
     */
    Location fetch( Location rowid ) throws IOException
    {
        TranslationPage xlatPage = TranslationPage.getTranslationPageView( recordFile.get( rowid.getBlock() ) );
        
        try
        {
            Location retval = new Location( xlatPage.get( rowid.getOffset() ) );
            return retval;
        }
        finally
        {
            recordFile.release( rowid.getBlock(), false );
        }
    }

}
