/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.pig.backend.local.executionengine.physicalLayer.relationalOperators;
import java.util.Iterator;
import java.util.List;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.POStatus;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.Result;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.plans.PhyPlanVisitor;
import org.apache.pig.data.BagFactory;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
import org.apache.pig.impl.plan.OperatorKey;
import org.apache.pig.impl.plan.VisitorException;
import org.apache.pig.pen.util.ExampleTuple;
/**
* This is a local implementation of the cross. Its a blocking operator.
* It accumulates inputs into databags and then applies logic similar to
* foreach flatten(*) to get the output tuples
*
*
*/
public class POCross extends PhysicalOperator {
DataBag [] inputBags;
Tuple [] data;
Iterator [] its;
public POCross(OperatorKey k) {
super(k);
// TODO Auto-generated constructor stub
}
public POCross(OperatorKey k, int rp) {
super(k, rp);
// TODO Auto-generated constructor stub
}
public POCross(OperatorKey k, List<PhysicalOperator> inp) {
super(k, inp);
// TODO Auto-generated constructor stub
}
public POCross(OperatorKey k, int rp, List<PhysicalOperator> inp) {
super(k, rp, inp);
// TODO Auto-generated constructor stub
}
@Override
public void visit(PhyPlanVisitor v) throws VisitorException {
// TODO Auto-generated method stub
v.visitCross(this);
}
@Override
public Result getNext(Tuple t) throws ExecException {
Result res = new Result();
int noItems = inputs.size();
if(inputBags == null) {
accumulateData();
}
if(its != null) {
//we check if we are done with processing
//we do that by checking if all the iterators are used up
boolean finished = true;
for(int i = 0; i < its.length; i++) {
finished &= !its[i].hasNext();
}
if(finished) {
res.returnStatus = POStatus.STATUS_EOP;
return res;
}
}
if(data == null) {
//getNext being called for the first time or starting on new input data
//we instantiate the template array and start populating it with data
data = new Tuple[noItems];
for(int i = 0; i < noItems; ++i) {
data[i] = (Tuple) its[i].next();
}
res.result = CreateTuple(data);
res.returnStatus = POStatus.STATUS_OK;
return res;
} else {
for(int index = noItems - 1; index >= 0; --index) {
if(its[index].hasNext()) {
data[index] = (Tuple) its[index].next();
res.result = CreateTuple(data);
res.returnStatus = POStatus.STATUS_OK;
return res;
}
else{
// reset this index's iterator so cross product can be achieved
// we would be resetting this way only for the indexes from the end
// when the first index which needs to be flattened has reached the
// last element in its iterator, we won't come here - instead, we reset
// all iterators at the beginning of this method.
its[index] = (inputBags[index]).iterator();
data[index] = (Tuple) its[index].next();
}
}
}
return null;
}
private void accumulateData() throws ExecException {
int count = 0;
inputBags = new DataBag[inputs.size()];
its = new Iterator[inputs.size()];
for(PhysicalOperator op : inputs) {
DataBag bag = BagFactory.getInstance().newDefaultBag();
inputBags[count] = bag;
for(Result res = op.getNext(dummyTuple); res.returnStatus != POStatus.STATUS_EOP; res = op.getNext(dummyTuple)) {
if(res.returnStatus == POStatus.STATUS_NULL)
continue;
if(res.returnStatus == POStatus.STATUS_ERR)
throw new ExecException("Error accumulating data in the local Cross operator");
if(res.returnStatus == POStatus.STATUS_OK)
bag.add((Tuple) res.result);
}
its[count++] = bag.iterator();
}
}
private Tuple CreateTuple(Tuple[] data) throws ExecException {
Tuple out = TupleFactory.getInstance().newTuple();
for(int i = 0; i < data.length; ++i) {
Tuple t = data[i];
int size = t.size();
for(int j = 0; j < size; ++j) {
out.append(t.get(j));
}
}
if(lineageTracer != null) {
ExampleTuple tOut = new ExampleTuple();
tOut.reference(out);
lineageTracer.insert(tOut);
for(int i = 0; i < data.length; i++) {
lineageTracer.union(tOut, data[i]);
}
return tOut;
}
return out;
}
@Override
public String name() {
// TODO Auto-generated method stub
return "POCrossLocal" + " - " + mKey.toString();
}
@Override
public boolean supportsMultipleInputs() {
// TODO Auto-generated method stub
return true;
}
@Override
public boolean supportsMultipleOutputs() {
// TODO Auto-generated method stub
return false;
}
}