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package de.lmu.ifi.dbs.elki.persistent;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2012
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import gnu.trove.map.TIntObjectMap;
import gnu.trove.map.hash.TIntObjectHashMap;
/**
* A memory based implementation of a PageFile that simulates I/O-access.<br>
* Implemented as a Map with keys representing the ids of the saved pages.
*
* @author Elke Achtert
*
* @param <P> Page type
*/
public class MemoryPageFile<P extends Page> extends AbstractStoringPageFile<P> {
/**
* Holds the pages.
*/
private final TIntObjectMap<P> file;
/**
* Creates a new MemoryPageFile that is supported by a cache with the
* specified parameters.
*
* @param pageSize the size of a page in Bytes
*/
public MemoryPageFile(int pageSize) {
super(pageSize);
this.file = new TIntObjectHashMap<P>();
}
@Override
public synchronized P readPage(int pageID) {
readAccess++;
return file.get(pageID);
}
@Override
protected void writePage(int pageID, P page) {
writeAccess++;
file.put(pageID, page);
page.setDirty(false);
}
@Override
public synchronized void deletePage(int pageID) {
// put id to empty nodes and
// delete from cache
super.deletePage(pageID);
// delete from file
writeAccess++;
file.remove(pageID);
}
@Override
public void clear() {
file.clear();
}
}
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