cachedrow.java

一个用java写的开源的数据库系统

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 * This product includes Hypersonic SQL.
 * Originally developed by Thomas Mueller and the Hypersonic SQL Group. 
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 * All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
 *
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 * list of conditions and the following disclaimer, including earlier
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 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
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 * license statements (above) and comply with all above license conditions.
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package org.hsqldb;

import java.io.IOException;
import java.sql.SQLException;

// fredt@users 20020221 - patch 513005 by sqlbob@users (RMP)
// fredt@users 20020920 - path 1.7.1 by fredt - refactoring to cut mamory footprint

/**
 *  Disk and In-memory representation of a database row object with storage
 *  independent methods for serialization and de-serialization.
 *
 * @version 1.7.1
 */
class CachedRow extends Row {

    static final int NO_POS         = -1;
    static int       iCurrentAccess = 0;
    protected Table  tTable;
    int              iLastAccess;
    CachedRow        rLast, rNext;
    int              iPos = NO_POS;
    int              storageSize;
    private boolean  bChanged;

    /**
     *  Constructor declaration
     *
     * @param  t
     * @param  o
     * @exception  SQLException  Description of the Exception
     */
    CachedRow(Table t, Object o[]) throws SQLException {

        tTable = t;

        int index = t.getIndexCount();

        nPrimaryNode = Node.newNode(this, 0, t);

        Node n = nPrimaryNode;

        for (int i = 1; i < index; i++) {
            n.nNext = Node.newNode(this, i, t);
            n       = n.nNext;
        }

        oData       = o;
        bChanged    = true;
        iLastAccess = iCurrentAccess++;

        t.putRow(this);
    }

    void setPos(int pos) {

        iPos = pos;

        Node n = nPrimaryNode;

        while (n != null) {
            n.setKey(pos);

            n = n.nNext;
        }
    }

    void changed() {
        bChanged    = true;
        iLastAccess = iCurrentAccess++;
    }

    boolean hasChanged() {
        return (bChanged);
    }

    /**
     * Get the node for a given index.
     *
     * @param  index
     * @return the node
     */
    Node getNode(int index) {

        iLastAccess = iCurrentAccess++;

        return super.getNode(index);
    }

    /**
     *  Method declaration
     *
     * @param  n
     * @return
     */
    Node getNextNode(Node n) {

        iLastAccess = iCurrentAccess++;

        return super.getNextNode(n);
    }

    /**
     *  Method declaration
     *
     * @return
     */
    Object[] getData() {

        iLastAccess = iCurrentAccess++;

        return oData;
    }

    /**
     *  Method declaration
     *
     * @return
     */
    Table getTable() {
        return tTable;
    }

    /**
     *  Method declaration
     *
     * @param  before
     */
    void insert(CachedRow before) {

        Record.memoryRecords++;

        if (before == null) {
            rNext = this;
            rLast = this;
        } else {
            rNext        = before;
            rLast        = before.rLast;
            before.rLast = this;
            rLast.rNext  = this;
        }
    }

// fredt@users 20020221 - patch 513005 by sqlbob@users (RMP)
// method renamed

    /**
     * Used only in Cache.java to avoid removing the row from the cache
     *
     *
     * @return
     * @throws  SQLException
     */
    boolean isRoot() throws SQLException {

        Node n = nPrimaryNode;

        while (n != null) {
            if (Trace.DOASSERT) {
                Trace.doAssert(n.getBalance() != -2);
            }

            if (Trace.STOP) {
                Trace.stop();
            }

            if (n.isRoot()) {
                return true;
            }

            n = n.nNext;
        }

        return false;
    }

    /**
     *  Method declaration
     *
     * @param  out            Description of the Parameter
     * @throws  IOException
     * @throws  SQLException
     */
    void write(DatabaseRowOutputInterface out)
    throws IOException, SQLException {

        out.writeSize(storageSize);

        if (tTable.isIndexCached()) {
            Node n = nPrimaryNode;

            while (n != null) {
                n.write(out);

                n = n.nNext;
            }
        }

        out.writeData(oData, tTable);
        out.writePos(iPos);

        bChanged = false;
    }

    /**
     *  Method declaration
     *
     * @throws  SQLException
     */
    void delete() throws SQLException {

        Record.memoryRecords++;

        bChanged = false;

        tTable.removeRow(this);

        rNext        = null;
        rLast        = null;
        tTable       = null;
        oData        = null;
        nPrimaryNode = null;
    }

    /**
     *  Method declaration
     *
     * @throws  SQLException
     */
    void free() throws SQLException {

        rLast.rNext = rNext;
        rNext.rLast = rLast;

        if (rNext == this) {
            rNext = rLast = null;
        }
    }

    /**
     *  constructor when read from cache
     *
     * @param  t
     * @param  in
     * @exception  IOException   Description of the Exception
     * @exception  SQLException  Description of the Exception
     */
    CachedRow(Table t,
              DatabaseRowInputInterface in) throws IOException, SQLException {

        tTable      = t;
        iPos        = in.getPos();
        storageSize = in.getSize();

        int index = t.getIndexCount();

        nPrimaryNode = Node.newNode(this, in, 0, t);

        Node n = nPrimaryNode;

        if (t.getIndexType() == Index.POINTER_INDEX) {
            ((PointerNode) nPrimaryNode).setNextKey(in.getNextPos());
        }

        for (int i = 1; i < index; i++) {
            n.nNext = Node.newNode(this, in, i, t);
            n       = n.nNext;
        }

        oData = in.readData(tTable.getColumnTypes());

        if (tTable.isIndexCached()) {
            Trace.check(in.readIntData() == iPos, Trace.INPUTSTREAM_ERROR);
        }

        iLastAccess = iCurrentAccess++;
    }
}