/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other materials provided with the distribution.
* - Neither the name of the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package lupos.engine.operators.multiinput.join;
import java.util.HashSet;
import java.util.Iterator;
import lupos.datastructures.bindings.Bindings;
import lupos.datastructures.bindings.BindingsFactory;
import lupos.datastructures.items.BindingsComparator;
import lupos.datastructures.queryresult.ParallelIterator;
import lupos.datastructures.queryresult.QueryResult;
import lupos.engine.operators.messages.BindingsFactoryMessage;
import lupos.engine.operators.messages.Message;
import lupos.engine.operators.messages.StartOfEvaluationMessage;
import lupos.engine.operators.multiinput.mergeunion.MergeIterator;
public class MergeJoinWithoutSortingSeveralIterations extends Join {
/**
*
*/
private static final long serialVersionUID = 5051512203278340771L;
protected QueryResult left = null;
protected QueryResult right = null;
protected BindingsComparator comp = new BindingsComparator();
protected BindingsFactory bindingsFactory;
/**
* This method pre-processes the StartOfStreamMessage
*
* @param msg
* the message to be pre-processed
* @return the pre-processed message
*/
@Override
public Message preProcessMessage(final StartOfEvaluationMessage msg) {
if (this.left != null) {
this.left.release();
}
if (this.right != null) {
this.right.release();
}
this.left = null;
this.right = null;
return super.preProcessMessage(msg);
}
@Override
public Message preProcessMessage(final BindingsFactoryMessage msg){
this.bindingsFactory = msg.getBindingsFactory();
return msg;
}
@SuppressWarnings("unchecked")
@Override
public QueryResult process(final QueryResult bindings, final int operandID) {
bindings.materialize();
this.comp.setVariables(this.intersectionVariables);
final QueryResult oldLeft = this.left;
final QueryResult oldRight = this.right;
if (operandID == 0) {
if (this.left == null) {
this.left = bindings;
} else {
this.left = QueryResult.createInstance(new MergeIterator<Bindings>(this.comp, this.left.iterator(), bindings.iterator()));
}
} else if (operandID == 1) {
if (this.right == null) {
this.right = bindings;
} else {
this.right = QueryResult.createInstance(new MergeIterator<Bindings>(this.comp, this.right.iterator(), bindings.iterator()));
}
} else {
System.err.println("MergeJoin is a binary operator, but received the operand number "
+ operandID);
}
if (this.left != null && this.right != null) {
this.left.materialize();
this.right.materialize();
final Iterator<Bindings> leftIterator = (operandID == 0 && oldLeft != null) ? new MinusIterator(
bindings.iterator(), oldLeft.iterator())
: this.left.iterator();
final QueryResult rightLocal = (operandID == 1 && oldRight != null) ? QueryResult
.createInstance(new MinusIterator(bindings.iterator(),
oldRight.iterator()))
: this.right;
final ParallelIterator<Bindings> currentResult = (this.intersectionVariables
.size() == 0) ? MergeJoin.cartesianProductIterator(
leftIterator, rightLocal) : MergeJoin.mergeJoinIterator(
leftIterator, rightLocal.iterator(), this.comp,
this.intersectionVariables, this.bindingsFactory);
if (currentResult != null && currentResult.hasNext()) {
final QueryResult result = QueryResult
.createInstance(new ParallelIterator<Bindings>() {
int number = 0;
@Override
public void close() {
currentResult.close();
}
@Override
public boolean hasNext() {
if (!currentResult.hasNext()) {
MergeJoinWithoutSortingSeveralIterations.this.realCardinality = this.number;
this.close();
}
return currentResult.hasNext();
}
@Override
public Bindings next() {
final Bindings b = currentResult.next();
if (!currentResult.hasNext()) {
MergeJoinWithoutSortingSeveralIterations.this.realCardinality = this.number;
this.close();
}
if (b != null) {
this.number++;
}
return b;
}
@Override
public void remove() {
currentResult.remove();
}
@Override
public void finalize() {
this.close();
}
});
return result;
} else {
return null;
}
} else {
return null;
}
}
public class MinusIterator implements ParallelIterator<Bindings> {
final Iterator<Bindings> it;
final Iterator<Bindings> minus;
final HashSet<Bindings> currentMinusMap = new HashSet<Bindings>();
Bindings currentMinus = null;
Bindings nextMinus = null;
Bindings next = null;
public MinusIterator(final Iterator<Bindings> it,
final Iterator<Bindings> minus) {
this.it = it;
this.minus = minus;
this.nextMap();
}
@Override
public void close() { // nothing to close...
}
@Override
public boolean hasNext() {
if (this.next == null) {
this.next = this.computeNext();
}
return (this.next != null);
}
@Override
public Bindings next() {
if (this.next != null) {
final Bindings znext = this.next;
this.next = null;
return znext;
} else {
return this.computeNext();
}
}
private Bindings computeNext() {
while (true) {
if (!this.it.hasNext()) {
return null;
}
final Bindings next_local = this.it.next();
if (next_local == null) {
return null;
}
while (true) {
if (this.currentMinus == null) {
return next_local;
}
final int compare = MergeJoinWithoutSortingSeveralIterations.this.comp.compare(next_local, this.currentMinus);
if (compare == 0) {
if (this.currentMinusMap.contains(next_local)) {
break;
} else {
return next_local;
}
}
if (compare < 0) {
return next_local;
}
this.nextMap();
}
}
}
private void nextMap() {
this.currentMinusMap.clear();
if (this.nextMinus == null && this.minus.hasNext()) {
this.nextMinus = this.minus.next();
}
if (this.nextMinus != null) {
this.currentMinus = this.nextMinus;
this.currentMinusMap.add(this.nextMinus);
this.nextMinus = null;
while (this.minus.hasNext()) {
this.nextMinus = this.minus.next();
if (MergeJoinWithoutSortingSeveralIterations.this.comp.compare(this.nextMinus, this.currentMinus) == 0) {
this.currentMinusMap.add(this.nextMinus);
} else {
break;
}
this.nextMinus = null;
}
} else {
this.currentMinus = null;
}
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
}