Quadcap Embeddable Database

com/quadcap/sql/ModIndexEntry.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.index.Btree;

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

/**
 * Abstract log step for all operations that modify indexes.
 *
 * @author Stan Bailes
 */
public abstract class ModIndexEntry extends LogStep implements Externalizable {
    transient Btree             index;
    transient Constraint        constraint;

    String                      tableName;
    String                      constraintName;
    
    byte[]                      key;

    /**
     * Default constructor
     */
    public ModIndexEntry() {}
    
    public ModIndexEntry(Session session, Constraint constraint, byte[] key) {
        super(session);
        this.constraint = constraint;
        this.key = key;
    }

    Btree getIndex(Session session) throws IOException {
        if (index == null) {
            Database db = session.getDatabase();
            if (constraint == null) {
                Table table = (Table)db.getRelation(tableName);
                constraint = table.getConstraint(constraintName);
                if (constraint == null) {
                    throw new RuntimeException("No constraint: " +
                                               constraintName);
                }
            }
            index = constraint.getIndex(db);
            if (index == null) {
                throw new RuntimeException("No index for table: " + tableName);
            }
        }
        return index;
    }
    
    abstract public void redo(Session session)
        throws IOException, SQLException
    ;

    abstract public void undo(Session session)
        throws IOException, SQLException
    ;

    public void prepare(Session session) throws IOException {}

    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        super.readExternal(in);
        tableName = (String)in.readObject();
        constraintName = (String)in.readObject();
        int cnt = in.readInt();
        key = new byte[cnt];
        in.read(key);
    }
    
    public void writeExternal(ObjectOutput out) throws IOException {
        super.writeExternal(out);
        if (tableName == null) {
            tableName = constraint.getTable().getName();
            constraintName = constraint.getName();
        }
        out.writeObject(tableName);
        out.writeObject(constraintName);
        out.writeInt(key.length);
        out.write(key);
    }

    //#ifdef DEBUG
    public String toString() {
        StringBuffer sb = new StringBuffer(super.toString());
        sb.append(" ModIndexEntry(");
        sb.append(Util.hexBytes(key));
        sb.append(')');
        return sb.toString();
    }
    //#endif
}