timsants commented on a change in pull request #6046: URL: https://github.com/apache/incubator-pinot/pull/6046#discussion_r495615360
########## File path: pinot-spi/src/main/java/org/apache/pinot/spi/data/readers/AbstractDefaultRecordExtractor.java ########## @@ -0,0 +1,166 @@ +/** + * 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; + + +/** + * 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 + * @param <V> value used for converting the nested/complex fields of the file format (e.g. GenericRecord for Avro). + * In most cases, this will be the same type as {@code T}. + */ +public abstract class AbstractDefaultRecordExtractor<T, V> implements RecordExtractor<T, Object> { + + /** + * Converts the field value to either a single value (string, number, bytebuffer), multi value (Object[]) or a Map. + * Returns {@code null} if the field value is {@code null}. + * + * 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(@Nullable Object value) { + if (value == null) { + return null; + } + Object convertedValue; + if (isInstanceOfMultiValue(value)) { + convertedValue = convertMultiValue(value); + } else if (isInstanceOfMap(value)) { + convertedValue = convertMap(value); + } else if (isInstanceOfRecord(value)) { + convertedValue = convertRecord((V) value); + } else { + convertedValue = convertSingleValue(value); + } + return convertedValue; + } + + /** + * Returns whether the object is an instance of the data format's base type. + */ + protected abstract boolean isInstanceOfRecord(Object value); + + /** + * 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. + */ + @Nullable + protected abstract Object convertRecord(V value); + + /** + * 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 = 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()) { + convertedMap.put(convertSingleValue(key), convert(map.get(key))); + } + 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: This method is called for converting map keys without checking for `null`. I believe it is possible to have a `null` map key but do we want to accept this case? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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