Quadcap Embeddable Database

com/quadcap/sql/DeleteIndexEntry.java

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package com.quadcap.sql;

/* 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.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import java.sql.SQLException;

import com.quadcap.sql.file.BlockFile;
import com.quadcap.sql.file.ByteUtil;
import com.quadcap.sql.file.SubPageManager;
import com.quadcap.sql.io.Extern;

import com.quadcap.sql.index.Btree;

import com.quadcap.util.Debug;
import com.quadcap.util.Util;

/**
 * Log step to delete an index entry.
 *
 * @author Stan Bailes
 */
public class DeleteIndexEntry extends ModIndexEntry
implements Externalizable {
    byte[]                      data;

    /**
     * Default constructor
     */
    public DeleteIndexEntry() {}

    /**
     * Explicit constructor
     */
    public DeleteIndexEntry(Session session, Constraint constraint,
                            byte[] key) {
        super(session, constraint, key);
    }

    public void redo(Session session) throws IOException, SQLException {
        if (index == null) getIndex(session);
        index.delete(key);
    }

    public void undo(Session session) throws IOException {
        if (data != null) {
            if (index == null) getIndex(session);
            long rowId = ByteUtil.getLong(data, 0);
            ByteUtil.putLong(data, 0, session.getLog().getRowMap(rowId));
            index.set(key, data);
        }
    }

    public void prepare(Session session) throws IOException {
        if (index == null) getIndex(session);
        this.data = index.get(key);
    }

    /**
     * Read me from a stream
     *
     * @exception IOException may be thrown
     */
    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        super.readExternal(in);
        this.data = null;
        int cnt = in.readInt();
        if (cnt > 0) {
            data = new byte[cnt];
            in.read(data);
        }
    }
    
    /**
     * Write me to a stream
     *
     * @exception IOException may be thrown
     */
    public void writeExternal(ObjectOutput out) throws IOException {
        super.writeExternal(out);
        if (data == null) {
            out.writeInt(0);
        } else {
            out.writeInt(data.length);
            out.write(data);
        }
    }

    //#ifdef DEBUG
    /**
     * Return string representation for debugging
     */
    public String toString() {
        return "Del: " + super.toString() + ", rowId = " +
            (data != null && data.length >= 8
             ? SubPageManager.toString(ByteUtil.getLong(data, 0))
             : "<NULL>");
    }
    //#endif

    /**
     * My class's extern object
     */
    static Extern extern;
    public void setExtern(Extern extern) { DeleteIndexEntry.extern = extern; }
    public Extern getExtern() { return extern; }
}