/*******************************************************************************
* Copyright (c) 2000, 2003 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* MetaMatrix, Inc - repackaging and updates for use as a metadata store
*******************************************************************************/
package org.teiid.designer.core.index;
import java.io.IOException;
import java.io.RandomAccessFile;
/**
* A block is a container that can hold information (a list of file names, a list of
* words, ...), be saved on the disk and loaded in memory.
*
* @since 8.0
*/
public abstract class Block {
/**
* Size of the block
*/
protected int blockSize;
/**
* Field in which the information is stored
*/
protected Field field;
public Block(int blockSize) {
this.blockSize= blockSize;
field= new Field(blockSize);
}
/**
* Empties the block.
*/
public void clear() {
field.clear();
}
/**
* Flushes the block
*/
public void flush() {
}
/**
* Loads the block with the given number in memory, reading it from a RandomAccessFile.
*/
public void read(RandomAccessFile raf, int blockNum) throws IOException {
raf.seek(blockNum * (long) blockSize);
raf.readFully(field.buffer());
}
/**
* Writes the block in a RandomAccessFile, giving it a block number.
*/
public void write(RandomAccessFile raf, int blockNum) throws IOException {
raf.seek(blockNum * (long) blockSize);
raf.write(field.buffer());
}
}