/**
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 Oct 22, 2010
*/
package com.bigdata.bop.engine;
import com.bigdata.bop.IBindingSet;
/**
* Interface dispatches an {@link IBindingSet}[] chunk generated by a running
* operator task. Each task may produce zero or more such chunks. The chunks may
* be combined together by the caller in order to have "chunkier" processing by
* this interface. The interface is responsible for generating the appropriate
* {@link IChunkMessage}(s) for each {@link IBindingSet}[] chunk. In standalone
* there is a one-to-one relationship between input chunks and output messages.
* In scale-out, we map each {@link IBindingSet} over the shard(s) for the next
* operator, which is a many-to-one mapping.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
*/
public interface IChunkHandler {
/**
* Take an {@link IBindingSet}[] chunk generated by some pass over an
* operator and make it available to the target operator. How this is done
* depends on whether the query is running against a standalone database or
* the scale-out database.
* <p>
* Note: The return value is used as part of the termination criteria for
* the query which depends on (a) the #of running operator tasks and (b) the
* #of {@link IChunkMessage}s generated (available) and consumed. The return
* value of this method increases the #of {@link IChunkMessage}s available
* to the query.
*
* @param query
* The query.
* @param bopId
* The operator which wrote on the sink.
* @param sinkId
* The identifier of the target operator.
* @param chunk
* The intermediate results to be passed to that target operator.
*
* @return The #of {@link IChunkMessage} sent. This will always be ONE (1)
* for scale-up. For scale-out, there will be at least one
* {@link IChunkMessage} per index partition over which the
* intermediate results were mapped.
*/
int handleChunk(IRunningQuery query, int bopId, int sinkId,
IBindingSet[] chunk);
}