| /* |
| * Copyright 2016, Yahoo! Inc. |
| * Licensed under the terms of the Apache License 2.0. See LICENSE file at the project root for terms. |
| */ |
| |
| package com.yahoo.sketches.pig.frequencies; |
| |
| import java.io.IOException; |
| |
| import org.apache.log4j.Logger; |
| import org.apache.pig.Accumulator; |
| import org.apache.pig.EvalFunc; |
| import org.apache.pig.backend.executionengine.ExecException; |
| import org.apache.pig.data.DataBag; |
| import org.apache.pig.data.Tuple; |
| |
| import com.yahoo.sketches.ArrayOfItemsSerDe; |
| import com.yahoo.sketches.frequencies.ItemsSketch; |
| |
| /** |
| * This is a generic implementation to be specialized in concrete UDFs |
| * @param <T> Type of item |
| */ |
| public abstract class UnionFrequentItemsSketch<T> extends EvalFunc<Tuple> implements Accumulator<Tuple> { |
| private final int sketchSize_; |
| private final ArrayOfItemsSerDe<T> serDe_; |
| private ItemsSketch<T> sketch_; |
| private boolean isFirstCall_ = true; |
| |
| /** |
| * Constructs a function given a sketch size and serde |
| * @param sketchSize parameter controlling the size of the sketch and the accuracy |
| * @param serDe an instance of ArrayOfItemsSerDe to serialize and deserialize arrays of items |
| */ |
| public UnionFrequentItemsSketch(final int sketchSize, final ArrayOfItemsSerDe<T> serDe) { |
| super(); |
| sketchSize_ = sketchSize; |
| serDe_ = serDe; |
| } |
| |
| @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("exec is used"); |
| isFirstCall_ = false; |
| } |
| if ((inputTuple == null) || (inputTuple.size() == 0)) { |
| return null; |
| } |
| accumulate(inputTuple); |
| final Tuple outputTuple = getValue(); |
| cleanup(); |
| return outputTuple; |
| } |
| |
| @Override |
| public void accumulate(final Tuple inputTuple) throws IOException { |
| if (isFirstCall_) { |
| // this is to see in the log which way was used by Pig |
| Logger.getLogger(getClass()).info("accumulator is used"); |
| isFirstCall_ = false; |
| } |
| if ((inputTuple == null) || (inputTuple.size() != 1)) { |
| return; |
| } |
| final Object obj = inputTuple.get(0); |
| if (!(obj instanceof DataBag)) { |
| return; |
| } |
| final DataBag bag = (DataBag) inputTuple.get(0); |
| if (bag.size() == 0) { |
| return; |
| } |
| |
| if (sketch_ == null) { |
| sketch_ = new ItemsSketch<T>(sketchSize_); |
| } |
| for (final Tuple innerTuple: bag) { |
| final int sz = innerTuple.size(); |
| if ((sz != 1) || (innerTuple.get(0) == null)) { |
| continue; |
| } |
| final ItemsSketch<T> incomingSketch = Util.deserializeSketchFromTuple(innerTuple, serDe_); |
| sketch_.merge(incomingSketch); |
| } |
| } |
| |
| @Override |
| public Tuple getValue() { |
| if (sketch_ == null) { //return an empty sketch |
| try { |
| return Util.serializeSketchToTuple(new ItemsSketch<T>(sketchSize_), serDe_); |
| } catch (final ExecException ex) { |
| throw new RuntimeException("Pig Error: " + ex.getMessage(), ex); |
| } |
| } |
| |
| try { |
| return Util.serializeSketchToTuple(sketch_, serDe_); |
| } catch (final ExecException ex) { |
| throw new RuntimeException("Pig Error: " + ex.getMessage(), ex); |
| } |
| } |
| |
| @Override |
| public void cleanup() { |
| if (sketch_ != null) { |
| sketch_.reset(); |
| } |
| } |
| |
| } |