Quadcap Embeddable Database

com/quadcap/sql/LazyRow.java

Go to the documentation of this file.

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.ByteArrayInputStream;
import java.io.IOException;

import java.sql.SQLException;

import com.quadcap.sql.io.ObjectInputStream;
import com.quadcap.sql.io.ObjectOutputStream;

import com.quadcap.sql.types.Type;
import com.quadcap.sql.types.Value;

import com.quadcap.sql.file.ByteArrayRandomAccess;
import com.quadcap.sql.file.Datafile;
import com.quadcap.sql.file.PageManager;
import com.quadcap.sql.file.RandomAccess;
import com.quadcap.sql.file.RandomAccessOutputStream;
import com.quadcap.sql.file.SubPageManager;

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

/**
 * A row that we deserialize only as needed to produce values. 
 *
 * @author Stan Bailes
 */
public class LazyRow extends Row {
    ByteArrayRandomAccess       ra;
    boolean[]                   dirty;

    public LazyRow(int size) {
        super(size);    
        this.dirty = new boolean[size + 1];
    }

    public void reset(RandomAccess rowBuf, Datafile db)
        throws IOException, SQLException
    {
        resetDirty();
        if (ra == null) {
            ra = new ByteArrayRandomAccess((int)rowBuf.size());
        }
        ra.resize(rowBuf.size());
        byte[] buf = ra.getBytes();
        rowBuf.read(0, buf, 0, (int)rowBuf.size());
        bulkLoad(db);
    }
        
    public void reset(byte[] buf, Datafile db)
        throws IOException, SQLException
    {
        resetDirty();
        if (ra == null) {
            ra = new ByteArrayRandomAccess(buf);
        } else {
            ra.reset(buf, buf.length);
        }
        bulkLoad(db);
    }

    final void bulkLoad(Datafile db) throws SQLException {
        try {
            ByteArrayInputStream bi = new ByteArrayInputStream(getBytes());
            ObjectInputStream oi = new ObjectInputStream(bi);
            int rsize = oi.readInt();
            if (rsize != size()) {
                throw new RuntimeException("Bad row size: " + rsize +
                                           " vs tuple size: " +  size());
            }
            this.blobCnt = oi.readInt();
            for (int i = 1; i <= rsize; i++) {
                Value vx = (Value)oi.readObject();
                if (db != null) vx.setDatafile(db);
                set(i, vx);
                dirty[i] = false;
            }
        } catch (Throwable e) {
            throw DbException.wrapThrowable(e);
        }
    }

    public final void resetDirty() {
        for (int i = 1; i <= size(); i++) {
            dirty[i] = false;
        }
    }        
        
    final boolean isDirty() {
        boolean d = false;
        for (int i = 1; i < dirty.length && !d; i++) {
            d = dirty[i];
        }
        return d;
    }
    
    public void set(int i, Value v) throws SQLException {
        super.set(i, v);
        dirty[i] = true;
    }


    final byte[] getBytes() throws IOException {
        byte[] ret = ra.getBytes();
        return ret;
    }

    final static byte[] writeRow(Session session, Tuple tuple, Row row)
        throws IOException, SQLException 
    {
        if (row instanceof LazyRow) {
            LazyRow lrow = (LazyRow)row;
            if (!lrow.isDirty()) {
                byte[] buf = lrow.getBytes();
                return buf;
            }
        }
        ObjectOutputStream out = session.oos;
        out.reset(null);        
        writeRow(tuple, row, out);
        byte[] ret = out.toByteArray();
        return ret;
    }

    //#ifdef DEBUG
    final static String tn(Value v) throws SQLException {
        StringBuffer sb = new StringBuffer(v.getType().toString());
        sb.append(":");
        sb.append(com.quadcap.sql.types.Value.tn(v));
        sb.append("(=");
        sb.append(String.valueOf(v));
        sb.append(')');
        return sb.toString();
    }
    //#endif
    
    final static void writeRow(Tuple tuple, Row row, ObjectOutputStream out)
        throws IOException, SQLException 
    {
        out.writeInt(row.size());
        out.writeInt(row.blobCnt);
        for (int i = 1; i <= row.size(); i++) {
            Value vx = row.item(i);
            if (tuple != null) {
                Type t = tuple.getColumn(i).getType();
                Value v1 = t.convert(vx);
                vx = v1;
            }
            out.writeObject(vx);            
        }
    }
}