/*
* 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.impl.builtin;
import java.io.IOException;
import java.util.Random;
import org.apache.pig.EvalFunc;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.data.BagFactory;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
public class GFCross extends EvalFunc<DataBag> {
int numInputs, myNumber, numGroupsPerInput;
BagFactory mBagFactory = BagFactory.getInstance();
TupleFactory mTupleFactory = TupleFactory.getInstance();
public static final int DEFAULT_PARALLELISM = 96;
@Override
public DataBag exec(Tuple input) throws IOException {
try{
numInputs = (Integer)input.get(0);
myNumber = (Integer)input.get(1);
DataBag output = mBagFactory.newDefaultBag();
numGroupsPerInput = (int) Math.ceil(Math.pow(DEFAULT_PARALLELISM, 1.0/numInputs));
int numGroupsGoingTo = (int) Math.pow(numGroupsPerInput,numInputs - 1);
int[] digits = new int[numInputs];
for (int i=0; i<numInputs; i++){
if (i == myNumber){
Random r = new Random(System.currentTimeMillis());
digits[i] = r.nextInt(numGroupsPerInput);
}else{
digits[i] = 0;
}
}
for (int i=0; i<numGroupsGoingTo; i++){
output.add(toTuple(digits));
next(digits);
}
return output;
}catch(ExecException e){
throw e;
}
}
private Tuple toTuple(int[] digits) throws IOException, ExecException{
Tuple t = mTupleFactory.newTuple(numInputs);
for (int i=0; i<numInputs; i++){
t.set(i, digits[i]);
}
return t;
}
private void next(int[] digits){
for (int i=0; i<numInputs; i++){
if (i== myNumber)
continue;
else{
if (digits[i] == numGroupsPerInput - 1){
digits[i] = 0;
}else{
digits[i]++;
break;
}
}
}
}
}