/* -*- tab-width: 4 -*-
*
* Electric(tm) VLSI Design System
*
* File: BTree.java
*
* Copyright (c) 2009, Oracle and/or its affiliates. All rights reserved.
*
* Electric(tm) is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* Electric(tm) is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Electric(tm); see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, Mass 02111-1307, USA.
*/
package com.sun.electric.database.geometry.btree;
import java.io.*;
/**
* Stores and retrieves fixed-size byte sequences indexed by a page
* number; page numbers are guaranteed to be contiguous starting at
* zero.
*/
public abstract class PageStorage {
private final int pageSize;
public PageStorage(int pageSize) { this.pageSize = pageSize; }
/** returns the size, in bytes, of each page */
public final int getPageSize() { return pageSize; }
/** creates a new page with undefined contents; returns its pageid */
public abstract int createPage();
/** returns the number of pages; all pageids strictly less than this are valid */
public abstract int getNumPages();
/** writes a page; throws an exception if the page did not exist */
public abstract void writePage(int pageid, byte[] buf, int ofs);
/** reads a page */
public abstract void readPage(int pageid, byte[] buf, int ofs);
/** ensure that the designated page is written to nonvolatile storage */
public abstract void fsync(int pageid);
/** close the PageStorage; invocation of any other methods after close() has undefined results */
public abstract void close();
}