/* XXL: The eXtensible and fleXible Library for data processing
Copyright (C) 2000-2011 Prof. Dr. Bernhard Seeger
Head of the Database Research Group
Department of Mathematics and Computer Science
University of Marburg
Germany
This library 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.
This library 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 this library; If not, see <http://www.gnu.org/licenses/>.
http://code.google.com/p/xxl/
*/
package xxl.core.util.memory;
/**
* Models an Object (e.g. an operator or a collection) whose memory usage can
* be monitored.
*/
public interface MemoryMonitorable {
/**
* A constant signing that the memory usage for an object is unknown.
*/
public static final int SIZE_UNKNOWN = -1;
/**
* A constant that should be used as key to store the objectsize in the
* composite meta data if the object provides metadata.
* @see xxl.core.util.metaData.MetaDataProvider MetaDataProvider-interface
*/
public static final String OBJECT_SIZE = "OBJECT_SIZE";
/**
* Returns the amount of memory, which is currently used by this object.
* This method can be called from the strategy of the memory manager to
* obtain useful information for distributing main memory among the
* memory using objects.
*
* @return Returns the amount of memory currently used by this object
* (in bytes).
*/
public abstract int getCurrentMemUsage();
}