/**
* File: $HeadURL: https://hdt-java.googlecode.com/svn/trunk/hdt-jena/src/org/rdfhdt/hdtjena/solver/OpExecutorHDT.java $
* Revision: $Rev: 190 $
* Last modified: $Date: 2013-03-03 11:30:03 +0000 (dom, 03 mar 2013) $
* Last modified by: $Author: mario.arias $
*
* 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 2.1 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Contacting the authors:
* Mario Arias: mario.arias@deri.org
* Javier D. Fernandez: jfergar@infor.uva.es
* Miguel A. Martinez-Prieto: migumar2@infor.uva.es
*/
package org.rdfhdt.hdtjena.solver;
import org.apache.jena.atlas.lib.Tuple;
import org.apache.jena.atlas.logging.Log;
import org.rdfhdt.hdtjena.HDTGraph;
import org.rdfhdt.hdtjena.HDTJenaConstants;
import org.rdfhdt.hdtjena.bindings.HDTId;
import org.apache.jena.graph.Graph;
import org.apache.jena.sparql.ARQInternalErrorException;
import org.apache.jena.sparql.algebra.Op;
import org.apache.jena.sparql.algebra.op.OpBGP;
import org.apache.jena.sparql.algebra.op.OpDistinct;
import org.apache.jena.sparql.algebra.op.OpFilter;
import org.apache.jena.sparql.algebra.op.OpReduced;
import org.apache.jena.sparql.algebra.optimize.TransformFilterPlacement;
import org.apache.jena.sparql.core.BasicPattern;
import org.apache.jena.sparql.core.Substitute;
import org.apache.jena.sparql.engine.ExecutionContext;
import org.apache.jena.sparql.engine.QueryIterator;
import org.apache.jena.sparql.engine.iterator.QueryIterPeek;
import org.apache.jena.sparql.engine.main.OpExecutor;
import org.apache.jena.sparql.engine.main.OpExecutorFactory;
import org.apache.jena.sparql.engine.main.QC;
import org.apache.jena.sparql.engine.optimizer.reorder.ReorderProc;
import org.apache.jena.sparql.engine.optimizer.reorder.ReorderTransformation;
import org.apache.jena.sparql.expr.ExprList;
import org.apache.jena.sparql.mgt.Explain;
import org.apache.jena.util.iterator.Filter;
public class OpExecutorHDT extends OpExecutor {
public final static OpExecutorFactory opExecFactoryHDT = new OpExecutorFactory()
{
@Override
public OpExecutor create(ExecutionContext execCxt)
{
return new OpExecutorHDT(execCxt) ;
}
};
private boolean isForHDT;
protected OpExecutorHDT(ExecutionContext execCtx) {
super(execCtx);
isForHDT = execCtx.getActiveGraph() instanceof HDTGraph ;
}
@Override
protected QueryIterator execute(OpDistinct opDistinct, QueryIterator input)
{
// FIXME: Add to context duplicates property.
return super.execute(opDistinct, input) ;
}
@Override
protected QueryIterator execute(OpReduced opReduced, QueryIterator input)
{
// FIXME: Add to context duplicates property.
return super.execute(opReduced, input) ;
}
@Override
protected QueryIterator execute(OpFilter opFilter, QueryIterator input)
{
if ( ! isForHDT )
return super.execute(opFilter, input) ;
// If the filter does not apply to the input??
// Where does ARQ catch this?
// (filter (bgp ...))
if ( OpBGP.isBGP(opFilter.getSubOp()) )
{
// Still may be a HDT graph in a non-HDT dataset (e.g. a named model)
HDTGraph graph = (HDTGraph)execCxt.getActiveGraph() ;
OpBGP opBGP = (OpBGP)opFilter.getSubOp() ;
return executeBGP(graph, opBGP, input, opFilter.getExprs(), execCxt) ;
}
// (filter (anything else))
return super.execute(opFilter, input) ;
}
// ---- Triple patterns
@Override
protected QueryIterator execute(OpBGP opBGP, QueryIterator input)
{
if ( ! isForHDT )
return super.execute(opBGP, input) ;
HDTGraph graph = (HDTGraph)execCxt.getActiveGraph() ;
return executeBGP(graph, opBGP, input, null, execCxt);
}
/** Execute a BGP (and filters) on a HDT graph, which may be in default storage or it may be a named graph */
private static QueryIterator executeBGP(HDTGraph graph, OpBGP opBGP, QueryIterator input, ExprList exprs,
ExecutionContext execCxt)
{
// Execute a BGP on the real default graph
return optimizeExecuteTriples(graph, input, opBGP.getPattern(), exprs, execCxt) ;
}
private static QueryIterator optimizeExecuteTriples(HDTGraph graph,
QueryIterator input, BasicPattern pattern, ExprList exprs,
ExecutionContext execCxt) {
if ( ! input.hasNext() )
return input ;
// -- Input
// Must pass this iterator into the next stage.
if ( pattern.size() >= 2 )
{
// Must be 2 or triples to reorder.
ReorderTransformation transform = graph.getReorderTransform() ;
if ( transform != null )
{
QueryIterPeek peek = QueryIterPeek.create(input, execCxt) ;
input = peek ; // Must pass on
pattern = reorder(pattern, peek, transform) ;
}
}
// -- Filter placement
Op op = null ;
if ( exprs != null )
op = TransformFilterPlacement.transform(exprs, pattern) ;
else
op = new OpBGP(pattern) ;
return plainExecute(op, input, execCxt) ;
}
/** Execute without modification of the op - does <b>not</b> apply special graph name translations */
private static QueryIterator plainExecute(Op op, QueryIterator input, ExecutionContext execCxt)
{
// -- Execute
// Switch to a non-reordering executor
// The Op may be a sequence due to TransformFilterPlacement
// so we need to do a full execution step, not go straight to the SolverLib.
ExecutionContext ec2 = new ExecutionContext(execCxt) ;
ec2.setExecutor(plainFactory) ;
// Solve without going through this executor again.
// There would be issues of nested patterns but this is only a
// (filter (bgp...)) or (filter (quadpattern ...)) or sequences of these.
// so there are no nested patterns to reorder.
return QC.execute(op, input, ec2) ;
}
private static BasicPattern reorder(BasicPattern pattern, QueryIterPeek peek, ReorderTransformation transform)
{
if ( transform != null )
{
// This works by getting one result from the peek iterator,
// and creating the more gounded BGP. The tranform is used to
// determine the best order and the transformation is returned. This
// transform is applied to the unsubstituted pattern (which will be
// substituted as part of evaluation.
if ( ! peek.hasNext() )
throw new ARQInternalErrorException("Peek iterator is already empty") ;
BasicPattern pattern2 = Substitute.substitute(pattern, peek.peek() ) ;
// Calculate the reordering based on the substituted pattern.
ReorderProc proc = transform.reorderIndexes(pattern2) ;
// Then reorder original patten
pattern = proc.reorder(pattern) ;
}
return pattern ;
}
private static OpExecutorFactory plainFactory = new OpExecutorPlainFactoryHDT() ;
private static class OpExecutorPlainFactoryHDT implements OpExecutorFactory
{
@Override
public OpExecutor create(ExecutionContext execCxt)
{
return new OpExecutorPlainHDT(execCxt) ;
}
}
/** An op executor that simply executes a BGP or QuadPattern without any reordering */
private static class OpExecutorPlainHDT extends OpExecutor
{
Filter<Tuple<HDTId>> filter;
@SuppressWarnings("unchecked")
public OpExecutorPlainHDT(ExecutionContext execCxt)
{
super(execCxt) ;
filter = (Filter<Tuple<HDTId>>)execCxt.getContext().get(HDTJenaConstants.FILTER_SYMBOL);
}
@Override
public QueryIterator execute(OpBGP opBGP, QueryIterator input)
{
Graph g = execCxt.getActiveGraph() ;
if ( g instanceof HDTGraph )
{
BasicPattern bgp = opBGP.getPattern() ;
Explain.explain("Execute", bgp, execCxt.getContext()) ;
// Triple-backed (but may be named as explicit default graph).
return HDTSolverLib.execute((HDTGraph)g, bgp, input, filter, execCxt) ;
}
Log.warn(this, "Non-HDTGraph passed to OpExecutorPlainHDT") ;
return super.execute(opBGP, input) ;
}
}
}