/*
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 Jun 20, 2008
*/
package com.bigdata.relation.accesspath;
import com.bigdata.relation.IMutableRelation;
import com.bigdata.relation.IRelation;
/**
* A buffer abstraction.
* <p>
* An {@link AbstractArrayBuffer} is generally used to write on an
* {@link IRelation} while {@link BlockingBuffer} may be used to feed an
* iterator on which another process will read asynchronously. An
* {@link UnsynchronizedArrayBuffer} may be used in single-threaded contexts and
* offers reduced synchronization overhead.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public interface IBuffer<E> {
/**
* The #of elements currently in the buffer.
*/
public int size();
/**
* True iff there are no elements in the buffer.
*/
public boolean isEmpty();
/**
* Add an element to the buffer.
*
* @param e
* The element
*/
public void add(E e);
/**
* Flush the buffer and return the #of elements written on the backing
* {@link IRelation} since the counter was last {@link #reset()} (the
* <i>mutationCount</i>).
* <p>
* Note: If the buffer does not write on an {@link IRelation} then it SHOULD
* return ZERO(0).
*
* @return The #of elements written on the backing {@link IRelation}.
*
* See {@link IMutableRelation}
*/
public long flush();
/**
* Reset the state of the buffer, including the counter whose value is
* reported by {@link #flush()}. Any data in the buffer will be discarded.
*/
public void reset();
}