sreemanamala commented on code in PR #16885: URL: https://github.com/apache/druid/pull/16885#discussion_r1732053363
########## processing/src/main/java/org/apache/druid/frame/read/columnar/StringArrayFrameColumnReader.java: ########## @@ -0,0 +1,520 @@ +/* + * 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 com.google.common.annotations.VisibleForTesting; +import com.google.common.primitives.Ints; +import it.unimi.dsi.fastutil.objects.ObjectArrays; +import org.apache.datasketches.memory.Memory; +import org.apache.druid.common.config.NullHandling; +import org.apache.druid.error.DruidException; +import org.apache.druid.frame.Frame; +import org.apache.druid.frame.read.FrameReaderUtils; +import org.apache.druid.frame.write.FrameWriterUtils; +import org.apache.druid.frame.write.columnar.FrameColumnWriters; +import org.apache.druid.frame.write.columnar.StringFrameColumnWriter; +import org.apache.druid.java.util.common.StringUtils; +import org.apache.druid.query.extraction.ExtractionFn; +import org.apache.druid.query.filter.DruidPredicateFactory; +import org.apache.druid.query.filter.ValueMatcher; +import org.apache.druid.query.monomorphicprocessing.RuntimeShapeInspector; +import org.apache.druid.query.rowsandcols.column.Column; +import org.apache.druid.query.rowsandcols.column.ColumnAccessorBasedColumn; +import org.apache.druid.query.rowsandcols.column.accessor.ObjectColumnAccessorBase; +import org.apache.druid.segment.DimensionDictionarySelector; +import org.apache.druid.segment.DimensionSelector; +import org.apache.druid.segment.DimensionSelectorUtils; +import org.apache.druid.segment.IdLookup; +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.column.DictionaryEncodedColumn; +import org.apache.druid.segment.data.IndexedInts; +import org.apache.druid.segment.data.RangeIndexedInts; +import org.apache.druid.segment.data.ReadableOffset; +import org.apache.druid.segment.vector.MultiValueDimensionVectorSelector; +import org.apache.druid.segment.vector.ReadableVectorInspector; +import org.apache.druid.segment.vector.ReadableVectorOffset; +import org.apache.druid.segment.vector.SingleValueDimensionVectorSelector; +import org.apache.druid.segment.vector.VectorObjectSelector; + +import javax.annotation.Nullable; +import java.nio.ByteBuffer; +import java.util.Comparator; + +/** + * Reader for {@link ColumnType#STRING_ARRAY}. + */ +public class StringArrayFrameColumnReader implements FrameColumnReader +{ + private 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); + + final long positionOfLengths = getStartOfStringLengthSection(frame.numRows()); + final long positionOfPayloads = getStartOfStringDataSection(memory, frame.numRows()); + + StringArrayFrameColumn frameCol = new StringArrayFrameColumn( + frame, + memory, + positionOfLengths, + positionOfPayloads + ); + + return new ColumnAccessorBasedColumn(frameCol); + } + + @Override + public ColumnPlus readColumn(final Frame frame) + { + final Memory memory = frame.region(columnNumber); + validate(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 + ); + } + } + + private static long getStartOfCumulativeLengthSection() + { + return StringFrameColumnWriter.DATA_OFFSET; + } + + private static long getStartOfStringLengthSection(final int numRows) + { + return StringFrameColumnWriter.DATA_OFFSET + (long) Integer.BYTES * numRows; + } + + private long getStartOfStringDataSection( + final Memory memory, + final int numRows + ) + { + if (numRows < 0) { + throw DruidException.defensive("Encountered -ve numRows [%s] while reading frame", numRows); + } + final int totalNumValues = FrameColumnReaderUtils.getAdjustedCumulativeRowLength( + memory, + getStartOfCumulativeLengthSection(), + numRows - 1 + ); + + return getStartOfStringLengthSection(numRows) + (long) Integer.BYTES * totalNumValues; + } + + @VisibleForTesting + private static class StringArrayFrameColumn extends ObjectColumnAccessorBase implements DictionaryEncodedColumn<String> + { + private final Frame frame; + private final Memory memory; + private final long startOfStringLengthSection; + private final long startOfStringDataSection; + + protected StringArrayFrameColumn( + Frame frame, + Memory memory, + long startOfStringLengthSection, + long startOfStringDataSection + ) + { + this.frame = frame; + this.memory = memory; + this.startOfStringLengthSection = startOfStringLengthSection; + this.startOfStringDataSection = startOfStringDataSection; + } + + @Override + public boolean hasMultipleValues() + { + // Only used in segment tests that don't run on frames. + throw new UnsupportedOperationException(); + } + + @Override + public int getSingleValueRow(int rowNum) + { + // Only used in segment tests that don't run on frames. + throw new UnsupportedOperationException(); + } + + @Override + public IndexedInts getMultiValueRow(int rowNum) + { + // Only used in segment tests that don't run on frames. + throw new UnsupportedOperationException(); + } + + @Nullable + @Override + public String lookupName(int id) + { + // Only used on columns from segments, not frames. + throw new UnsupportedOperationException(); + } + + @Override + public int lookupId(String name) + { + // Only used on columns from segments, not frames. + throw new UnsupportedOperationException(); + } + + @Override + public int getCardinality() + { + return DimensionDictionarySelector.CARDINALITY_UNKNOWN; + } + + @Override + public DimensionSelector makeDimensionSelector(ReadableOffset offset, @Nullable ExtractionFn extractionFn) + { + class MultipleValueSelector implements DimensionSelector Review Comment: updated to implement `makeColumnValueSelector` and made the `StringArrayFrameColumn` implement `ObjectColumnAccessorBase` to make it consistent with the `NumericArrayFrameColumn` When we take up the implicit casting work of getLong/getDouble etc, we might have to change only in `ObjectColumnAccessorBase` -- This is an automated message from the Apache Git Service. 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