src/main/java/org/apache/datasketches/pig/tuple/DataToArrayOfDoublesSketchAlgebraicIntermediateFinal.java

/*
 * 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.datasketches.pig.tuple;

import static org.apache.datasketches.Util.DEFAULT_NOMINAL_ENTRIES;

import java.io.IOException;

import org.apache.datasketches.memory.Memory;
import org.apache.datasketches.tuple.ArrayOfDoublesSetOperationBuilder;
import org.apache.datasketches.tuple.ArrayOfDoublesSketches;
import org.apache.datasketches.tuple.ArrayOfDoublesUnion;
import org.apache.datasketches.tuple.ArrayOfDoublesUpdatableSketch;
import org.apache.datasketches.tuple.ArrayOfDoublesUpdatableSketchBuilder;
import org.apache.log4j.Logger;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.DataByteArray;
import org.apache.pig.data.Tuple;

/**
 * Class used to calculate the intermediate pass (combiner) or the final pass
 * (reducer) of an Algebraic sketch operation. This may be called multiple times
 * (from the mapper and from the reducer). It will receive a bag of values
 * returned by either the Intermediate stage or the Initial stages, so
 * it needs to be able to differentiate between and interpret both types.
 */
abstract class DataToArrayOfDoublesSketchAlgebraicIntermediateFinal extends EvalFunc<Tuple> {
  private final int sketchSize_;
  private final float samplingProbability_;
  private final int numValues_;
  private boolean isFirstCall_ = true;

  DataToArrayOfDoublesSketchAlgebraicIntermediateFinal() {
    this(DEFAULT_NOMINAL_ENTRIES, 1);
  }

  DataToArrayOfDoublesSketchAlgebraicIntermediateFinal(final int numValues) {
    this(DEFAULT_NOMINAL_ENTRIES, numValues);
  }

  DataToArrayOfDoublesSketchAlgebraicIntermediateFinal(final int sketchSize, final int numValues) {
    this(sketchSize, 1f, numValues);
  }

  DataToArrayOfDoublesSketchAlgebraicIntermediateFinal(
      final int sketchSize, final float samplingProbability, final int numValues) {
    sketchSize_ = sketchSize;
    samplingProbability_ = samplingProbability;
    numValues_ = numValues;
  }

  @Override
  public Tuple exec(final Tuple inputTuple) throws IOException {
    if (isFirstCall_) {
      // this is to see in the log which way was used by Pig
      Logger.getLogger(getClass()).info("algebraic is used");
      isFirstCall_ = false;
    }
    final ArrayOfDoublesUnion union =
        new ArrayOfDoublesSetOperationBuilder().setNominalEntries(sketchSize_)
          .setNumberOfValues(numValues_).buildUnion();

    final DataBag bag = (DataBag) inputTuple.get(0);
    if (bag == null) {
      throw new IllegalArgumentException("InputTuple.Field0: Bag may not be null");
    }

    for (final Tuple dataTuple: bag) {
      final Object item = dataTuple.get(0);
      if (item instanceof DataBag) {
        // this is a bag from the Initial function.
        // just insert each item of the tuple into the sketch
        final ArrayOfDoublesUpdatableSketch sketch =
            new ArrayOfDoublesUpdatableSketchBuilder().setNominalEntries(sketchSize_)
              .setSamplingProbability(samplingProbability_).setNumberOfValues(numValues_).build();
        DataToArrayOfDoublesSketchBase.updateSketch((DataBag) item, sketch, numValues_);
        union.update(sketch);
      } else if (item instanceof DataByteArray) {
        // This is a sketch from a prior call to the
        // Intermediate function. merge it with the
        // current sketch.
        final DataByteArray dba = (DataByteArray) item;
        union.update(ArrayOfDoublesSketches.wrapSketch(Memory.wrap(dba.get())));
      } else {
        // we should never get here.
        throw new IllegalArgumentException("InputTuple.Field0: Bag contains unrecognized types: "
            + item.getClass().getName());
      }
    }
    return Util.tupleFactory.newTuple(new DataByteArray(union.getResult().toByteArray()));
  }
}