LakshSingla commented on code in PR #16885: URL: https://github.com/apache/druid/pull/16885#discussion_r1722678260
########## processing/src/main/java/org/apache/druid/frame/read/columnar/StringArrayFrameColumnReader.java: ########## @@ -0,0 +1,184 @@ +/* + * 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.druid.frame.read.columnar; + +import org.apache.datasketches.memory.Memory; +import org.apache.druid.error.DruidException; +import org.apache.druid.frame.Frame; +import org.apache.druid.frame.write.columnar.FrameColumnWriters; +import org.apache.druid.frame.write.columnar.StringFrameColumnWriter; +import org.apache.druid.query.rowsandcols.column.Column; +import org.apache.druid.query.rowsandcols.column.ColumnAccessorBasedColumn; +import org.apache.druid.segment.ColumnValueSelector; +import org.apache.druid.segment.column.BaseColumn; +import org.apache.druid.segment.column.ColumnCapabilitiesImpl; +import org.apache.druid.segment.column.ColumnType; +import org.apache.druid.segment.data.ReadableOffset; + +/** + * Reader for {@link ColumnType#STRING_ARRAY}. + */ +public class StringArrayFrameColumnReader implements FrameColumnReader +{ + final int columnNumber; + + /** + * Create a new reader. + * + * @param columnNumber column number + */ + StringArrayFrameColumnReader(int columnNumber) + { + this.columnNumber = columnNumber; + } + + @Override + public Column readRACColumn(Frame frame) + { + final Memory memory = frame.region(columnNumber); + validate(memory); + + // String arrays always store multiple values per row. + assert isMultiValue(memory); + final long positionOfLengths = getStartOfStringLengthSection(frame.numRows()); + final long positionOfPayloads = getStartOfStringDataSection(memory, frame.numRows()); + + StringFrameColumnReader.StringFrameColumn frameCol = new StringFrameColumnReader.StringFrameColumn( + frame, + true, + memory, + positionOfLengths, + positionOfPayloads, + true + ); + + return new ColumnAccessorBasedColumn(frameCol); + } + + @Override + public ColumnPlus readColumn(final Frame frame) + { + final Memory memory = frame.region(columnNumber); + validate(memory); + + // String arrays always store multiple values per row. + assert isMultiValue(memory); + final long startOfStringLengthSection = getStartOfStringLengthSection(frame.numRows()); + final long startOfStringDataSection = getStartOfStringDataSection(memory, frame.numRows()); + + final BaseColumn baseColumn = new StringArrayFrameColumn( + frame, + memory, + startOfStringLengthSection, + startOfStringDataSection + ); + + return new ColumnPlus( + baseColumn, + new ColumnCapabilitiesImpl().setType(ColumnType.STRING_ARRAY) + .setHasMultipleValues(false) + .setDictionaryEncoded(false), + frame.numRows() + ); + } + + private void validate(final Memory region) + { + // Check if column is big enough for a header + if (region.getCapacity() < StringFrameColumnWriter.DATA_OFFSET) { + throw DruidException.defensive("Column[%s] is not big enough for a header", columnNumber); + } + + final byte typeCode = region.getByte(0); + if (typeCode != FrameColumnWriters.TYPE_STRING_ARRAY) { + throw DruidException.defensive( + "Column[%s] does not have the correct type code; expected[%s], got[%s]", + columnNumber, + FrameColumnWriters.TYPE_STRING_ARRAY, + typeCode + ); + } + } + + static boolean isMultiValue(final Memory memory) + { + return memory.getByte(1) == 1; Review Comment: Is there a reference that we can use instead of 1? Something like the following: `memory.getByte(MULTI_VALUE_POSITION) = 1` or `memory.getByte(MULTI_VALUE_POSITION) = MULTI_VALUE` This would avoid the magic numbers in the code -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
