/*******************************************************************************
* Copyright (c) 2004, 2007 IBM Corporation and Cambridge Semantics Incorporated.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* File: $Source: /cvsroot/slrp/glitter/com.ibm.adtech.glitter/src/com/ibm/adtech/glitter/query/planning/Attic/OdoQueryOptimizer.java,v $
* Created by: Matthew Roy ( <a href="mailto:mroy@us.ibm.com">mroy@us.ibm.com </a>)
* Created on: Feb 8, 2007
* Revision: $Id: OdoQueryOptimizer.java 164 2007-07-31 14:11:09Z mroy $
*
* Contributors:
* IBM Corporation - initial API and implementation
* Cambridge Semantics Incorporated - Fork to Anzo
*******************************************************************************/
package org.openanzo.glitter.query.planning;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import org.openanzo.glitter.query.NodeCostModel;
import org.openanzo.glitter.query.QueryExecutionPlan;
import org.openanzo.glitter.syntax.abstrakt.TreeNode;
import org.openanzo.glitter.syntax.abstrakt.TriplePatternNode;
import org.openanzo.rdf.Variable;
/**
* The OdoQueryOptimizer attempts to prioritize evaluation of triple patterns with less free variables before those with more free variables.
*
* @author Matthew Roy ( <a href="mailto:mroy@cambridgesemantics.com">mroy@cambridgesemantics.com </a>)
*
*/
public class OdoQueryOptimizer implements QueryExecutionPlan {
//private static final Logger log = LoggerFactory.getLogger(OdoQueryOptimizer.class);
private final GreedyCostBasedExecutionPlan plan;
//private final IQuadStore quadStore;
/**
* Create optimizer
*
*/
public OdoQueryOptimizer() {
this(new SimpleCostModel());
}
public OdoQueryOptimizer(NodeCostModel costModel) {
plan = new GreedyCostBasedExecutionPlan(costModel);
}
public List<TreeNode> orderNodes(List<? extends TreeNode> nodes) {
TripleList list = new TripleList();
boolean allTPN = true;
List<TreeNode> ntNodes = new ArrayList<TreeNode>();
for (TreeNode node : nodes) {
if (!(node instanceof TriplePatternNode)) {
allTPN = false;
} else {
list.add((TriplePatternNode) node);
}
ntNodes.add(node);
}
if (allTPN) {
ArrayList<TreeNode> tnodes = new ArrayList<TreeNode>();
for (TreeNode tn : list) {
tnodes.add(tn);
}
return tnodes;
} else {
List<TreeNode> newNodes = this.plan.orderNodes(ntNodes);
LinkedList<TreeNode> uncompiled = new LinkedList<TreeNode>(newNodes);
Set<TreeNode> compiled = new LinkedHashSet<TreeNode>();
//VariableReferenceCount runningCount = new VariableReferenceCount();
while (!uncompiled.isEmpty()) {
TreeNode current = uncompiled.removeFirst();
compiled.add(current);
Collection<TreeNode> changedNodes = new TreeSet<TreeNode>(new TNNumberMatchComparator(current.getReferencedVariables()));
for (TreeNode uncompiledNode : uncompiled) {
if (tnVariablesMatch(current.getBindableVariables(), uncompiledNode)) {
changedNodes.add(uncompiledNode);
}
}
for (TreeNode changedNode : changedNodes) {
uncompiled.remove(changedNode);
compiled.add(changedNode);
}
}
ArrayList<TreeNode> tnodes = new ArrayList<TreeNode>();
for (TreeNode tn : compiled) {
tnodes.add(tn);
}
return tnodes;
}
}
private static boolean tnVariablesMatch(Set<Variable> vars, TreeNode node) {
for (Variable v : node.getReferencedVariables()) {
if (vars.contains(v))
return true;
}
return false;
}
private static class NumberMatchComparator implements Comparator<OdoTripleNode> {
Collection<Variable> variables;
NumberMatchComparator(Collection<Variable> variables) {
this.variables = variables;
}
public int compare(OdoTripleNode o1, OdoTripleNode o2) {
int a = 0;
int b = 0;
for (Variable var : variables) {
if (o1.checkMatch(var)) {
a++;
}
if (o2.checkMatch(var)) {
b++;
}
}
if (a > b)
return -1;
else if (b > a)
return 1;
else {
return o1.toString().compareTo(o2.toString());
}
}
}
private static class TNNumberMatchComparator implements Comparator<TreeNode> {
Collection<Variable> variables;
TNNumberMatchComparator(Collection<Variable> variables) {
this.variables = variables;
}
public int compare(TreeNode o1, TreeNode o2) {
int a = 0;
int b = 0;
for (Variable var : variables) {
if (o1.getReferencedVariables().contains(var)) {
a++;
}
if (o2.getReferencedVariables().contains(var)) {
b++;
}
}
if (a > b)
return -1;
else if (b > a)
return 1;
else {
return o1.toString().compareTo(o2.toString());
}
}
}
private static class TripleList implements Iterable<TreeNode> {
private final SortedSet<OdoTripleNode> sortedSet = new TreeSet<OdoTripleNode>();
private Set<OdoTripleNode> set = this.sortedSet;
private TripleList() {
}
private void add(TriplePatternNode tripleNode) {
OdoTripleNode node = new OdoTripleNode(tripleNode);//, quadStore);
this.sortedSet.add(node);
}
private void compile() {
// NOTE: the matched variables count is the number of variables in a
// triple that will be
// known by the time the query is run.
// Find the match variable values for all triples
Set<OdoTripleNode> compiled = new LinkedHashSet<OdoTripleNode>();
//VariableReferenceCount runningCount = new VariableReferenceCount();
while (!this.sortedSet.isEmpty()) {
OdoTripleNode current = this.sortedSet.first();
compiled.add(current);
this.sortedSet.remove(current);
Collection<OdoTripleNode> changedNodes = new TreeSet<OdoTripleNode>(new NumberMatchComparator(current.getVariables()));
for (Variable variable : current.getVariables()) {
for (OdoTripleNode uncompiledNode : this.sortedSet) {
if (uncompiledNode.checkMatch(variable)) {
changedNodes.add(uncompiledNode);
}
}
}
for (OdoTripleNode changedNode : changedNodes) {
this.sortedSet.remove(changedNode);
compiled.add(changedNode);
}
}
this.set = compiled;
}
public Iterator<TreeNode> iterator() {
compile();
List<TreeNode> list = new ArrayList<TreeNode>();
for (OdoTripleNode node : this.set) {
list.add(node.getTriple());
}
return list.iterator();
}
}
}