/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Nov 6, 2008
*/
package com.bigdata.btree;
/**
* A bloom filter that never reports <code>false</code> (this means that you
* must always check the index) and that does not permit anything to be added
* and, in fact, has no state.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
final public class NOPBloomFilter implements IBloomFilter {
public static final transient NOPBloomFilter INSTANCE = new NOPBloomFilter();
/**
* @throws UnsupportedOperationException
* always.
*/
public boolean add(byte[] key) {
throw new UnsupportedOperationException();
}
/**
* Returns <code>true</code>.
* <p>
* Note: The NOP filter returns <code>true</code> because a
* <code>true</code> return by a bloom filter means that you have to test
* the data, which is how we achieve NOP semantics. If this method were to
* return <code>false</code> then it would be claiming that the key was
* not in the index!!!
*
* @return <code>true</code>.
*/
public boolean contains(byte[] key) {
return true;
}
/**
* Returns <code>true</code>.
*/
public boolean isEnabled() {
return true;
}
public void falsePos() {
// NOP
}
}