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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) 2011
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/>.
*/
/**
* Abstract base class for the page file API for both caches and true page files
* (in-memory and on-disk).
*
* @author Erich Schubert
*
* @param <P> page type
*/
public abstract class AbstractPageFile<P extends Page> implements PageFile<P> {
/**
* The read I/O-Access of this file.
*/
protected long readAccess;
/**
* The write I/O-Access of this file.
*/
protected long writeAccess;
/**
* Constructor.
*/
public AbstractPageFile() {
super();
this.readAccess = 0;
this.writeAccess = 0;
}
/**
* Writes a page into this file. The method tests if the page has already an
* id, otherwise a new id is assigned and returned.
*
* @param page the page to be written
* @return the id of the page
*/
@Override
public final synchronized int writePage(P page) {
Integer pageid = setPageID(page);
writePage(pageid, page);
return pageid;
}
/**
* Perform the actual page write operation.
*
* @param pageid Page id
* @param page Page to write
*/
protected abstract void writePage(Integer pageid, P page);
@Override
public void close() {
clear();
}
@Override
public final long getReadOperations() {
return readAccess;
}
@Override
public final long getWriteOperations() {
return writeAccess;
}
@Override
public final void resetPageAccess() {
this.readAccess = 0;
this.writeAccess = 0;
}
}
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