npawar commented on a change in pull request #6046: URL: https://github.com/apache/incubator-pinot/pull/6046#discussion_r502576251
########## File path: pinot-spi/src/main/java/org/apache/pinot/spi/data/readers/BaseRecordExtractor.java ########## @@ -0,0 +1,174 @@ +/** + * 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.pinot.spi.data.readers; + +import java.nio.ByteBuffer; +import java.util.Arrays; +import java.util.Collection; +import java.util.HashMap; +import java.util.Map; +import javax.annotation.Nullable; + + +/** + * Base abstract class for extracting and converting the fields of various data formats into supported Pinot data types. + * + * @param <T> the format of the input record + */ +public abstract class BaseRecordExtractor<T> implements RecordExtractor<T> { + + /** + * Converts the field value to either a single value (string, number, byte[]), multi value (Object[]) or a Map. + * Returns {@code null} if the value is an empty array/collection/map. + * + * Natively Pinot only understands single values and multi values. + * Map is useful only if some ingestion transform functions operates on it in the transformation layer. + */ + @Nullable + public Object convert(Object value) { + Object convertedValue; + if (isInstanceOfMultiValue(value)) { + convertedValue = convertMultiValue(value); + } else if (isInstanceOfMap(value)) { + convertedValue = convertMap(value); + } else if (isInstanceOfRecord(value)) { + convertedValue = convertRecord(value); + } else { + convertedValue = convertSingleValue(value); + } + return convertedValue; + } + + /** + * Returns whether the object is an instance of the data format's base type. Override this method if the extractor + * can handle the conversion of nested record types. + */ + protected boolean isInstanceOfRecord(Object value) { + return false; + } + + /** + * Returns whether the object is of a multi-value type. Override this method if the data format represents + * multi-value objects differently. + */ + protected boolean isInstanceOfMultiValue(Object value) { + return value instanceof Collection; + } + + /** + * Returns whether the object is of a map type. Override this method if the data format represents map objects + * differently. + */ + protected boolean isInstanceOfMap(Object value) { + return value instanceof Map; + } + + /** + * Handles the conversion of every field of the object for the particular data format. Override this method if the + * extractor can convert nested record types. + */ + @Nullable + protected Object convertRecord(Object value) { + throw new UnsupportedOperationException("Extractor cannot convert record type structures for this data format."); + } + + /** + * Handles the conversion of each element of a multi-value object. Returns {@code null} if the field value is + * {@code null}. + * + * This implementation converts the Collection to an Object array. Override this method if the data format + * requires a different conversion for its multi-value objects. + */ + @Nullable + protected Object convertMultiValue(Object value) { + Collection collection = (Collection) value; + if (collection.isEmpty()) { + return null; + } + + int numValues = collection.size(); + Object[] array = new Object[numValues]; + int index = 0; + for (Object element : collection) { + Object convertedValue = null; + if (element != null) { + convertedValue = convert(element); + } + if (convertedValue != null && !convertedValue.toString().equals("")) { + array[index++] = convertedValue; + } + } + + if (index == numValues) { + return array; + } else if (index == 0) { + return null; + } else { + return Arrays.copyOf(array, index); + } + } + + /** + * Handles the conversion of every value of the map. Note that map keys will be handled as a single-value type. + * Returns {@code null} if the field value is {@code null}. This should be overridden if the data format requires + * a different conversion for map values. + */ + @Nullable + protected Object convertMap(Object value) { + Map map = (Map) value; + if (map.isEmpty()) { + return null; + } + + Map<Object, Object> convertedMap = new HashMap<>(); + for (Object key : map.keySet()) { + Object convertedValue = null; + if (key != null) { + convertedValue = convert(map.get(key)); + } + convertedMap.put(convertSingleValue(key), convertedValue); + } + return convertedMap; + } + + /** + * Converts single value types. This should be overridden if the data format requires + * a different conversion for its single values. Returns {@code null} for {@code null} input values. + */ + @Nullable + protected Object convertSingleValue(@Nullable Object value) { Review comment: Looks like you have put `if (value != null)` almost everywhere before calling convert, so this indeed won't be null. However, I prefer the way it used to be - no null checks in every single RecordExtractor, and instead handling null here, so we have lesser of the `if not null` lines. But I'll leave it up to you. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
