Github user julienledem commented on a diff in the pull request:
https://github.com/apache/spark/pull/9774#discussion_r45135353
--- Diff:
sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/SpecificParquetRecordReaderBase.java
---
@@ -0,0 +1,233 @@
+/*
+ * 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.spark.sql.execution.datasources.parquet;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.mapreduce.InputSplit;
+import org.apache.hadoop.mapreduce.RecordReader;
+import org.apache.hadoop.mapreduce.TaskAttemptContext;
+import org.apache.parquet.bytes.BytesInput;
+import org.apache.parquet.bytes.BytesUtils;
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.parquet.column.values.ValuesReader;
+import
org.apache.parquet.column.values.rle.RunLengthBitPackingHybridDecoder;
+import org.apache.parquet.filter2.compat.FilterCompat;
+import org.apache.parquet.hadoop.BadConfigurationException;
+import org.apache.parquet.hadoop.ParquetFileReader;
+import org.apache.parquet.hadoop.ParquetInputFormat;
+import org.apache.parquet.hadoop.ParquetInputSplit;
+import org.apache.parquet.hadoop.api.InitContext;
+import org.apache.parquet.hadoop.api.ReadSupport;
+import org.apache.parquet.hadoop.metadata.BlockMetaData;
+import org.apache.parquet.hadoop.metadata.ParquetMetadata;
+import org.apache.parquet.hadoop.util.ConfigurationUtil;
+import org.apache.parquet.schema.MessageType;
+import org.apache.spark.sql.catalyst.expressions.UnsafeRow;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.util.*;
+
+import static
org.apache.parquet.filter2.compat.RowGroupFilter.filterRowGroups;
+import static
org.apache.parquet.format.converter.ParquetMetadataConverter.NO_FILTER;
+import static
org.apache.parquet.format.converter.ParquetMetadataConverter.range;
+import static org.apache.parquet.hadoop.ParquetFileReader.readFooter;
+import static org.apache.parquet.hadoop.ParquetInputFormat.getFilter;
+
+/**
+ * Base class for custom RecordReaaders for Parquet that directly
materialize to `T`.
+ * This class handles computing row groups, filtering on them, setting up
the column readers,
+ * etc.
+ * TODO: move this to the parquet-mr project. There are performance
benefits of doing it
+ * this way, albeit at a higher cost to implement.
+ */
+public abstract class SpecificParquetRecordReaderBase<T> extends
RecordReader<Void, T> {
+ protected Path file;
+ protected MessageType fileSchema;
+ protected MessageType requestedSchema;
+ protected ReadSupport<T> readSupport;
+
+ /**
+ * The total number of rows this RecordReader will eventually read. The
sum of the
+ * rows of all the row groups.
+ */
+ protected long totalRowCount;
+
+ protected ParquetFileReader reader;
+
+ public void initialize(InputSplit inputSplit, TaskAttemptContext
taskAttemptContext)
+ throws IOException, InterruptedException {
+ Configuration configuration = taskAttemptContext.getConfiguration();
+ ParquetInputSplit split = (ParquetInputSplit)inputSplit;
+ this.file = split.getPath();
+ long[] rowGroupOffsets = split.getRowGroupOffsets();
+
+ ParquetMetadata footer;
+ List<BlockMetaData> blocks;
+
+ // if task.side.metadata is set, rowGroupOffsets is null
+ if (rowGroupOffsets == null) {
+ // then we need to apply the predicate push down filter
+ footer = readFooter(configuration, file, range(split.getStart(),
split.getEnd()));
+ MessageType fileSchema = footer.getFileMetaData().getSchema();
+ FilterCompat.Filter filter = getFilter(configuration);
+ blocks = filterRowGroups(filter, footer.getBlocks(), fileSchema);
+ } else {
+ // otherwise we find the row groups that were selected on the client
+ footer = readFooter(configuration, file, NO_FILTER);
+ Set<Long> offsets = new HashSet<>();
+ for (long offset : rowGroupOffsets) {
+ offsets.add(offset);
+ }
+ blocks = new ArrayList<>();
+ for (BlockMetaData block : footer.getBlocks()) {
+ if (offsets.contains(block.getStartingPos())) {
+ blocks.add(block);
+ }
+ }
+ // verify we found them all
+ if (blocks.size() != rowGroupOffsets.length) {
+ long[] foundRowGroupOffsets = new long[footer.getBlocks().size()];
+ for (int i = 0; i < foundRowGroupOffsets.length; i++) {
+ foundRowGroupOffsets[i] =
footer.getBlocks().get(i).getStartingPos();
+ }
+ // this should never happen.
+ // provide a good error message in case there's a bug
+ throw new IllegalStateException(
+ "All the offsets listed in the split should be found in the
file."
+ + " expected: " + Arrays.toString(rowGroupOffsets)
+ + " found: " + blocks
+ + " out of: " + Arrays.toString(foundRowGroupOffsets)
+ + " in range " + split.getStart() + ", " + split.getEnd());
+ }
+ }
+ MessageType fileSchema = footer.getFileMetaData().getSchema();
+ Map<String, String> fileMetadata =
footer.getFileMetaData().getKeyValueMetaData();
+ this.readSupport = getReadSupportInstance(
+ (Class<? extends ReadSupport<T>>)
getReadSupportClass(configuration));
+ ReadSupport.ReadContext readContext = readSupport.init(new InitContext(
+ taskAttemptContext.getConfiguration(),
toSetMultiMap(fileMetadata), fileSchema));
+ this.requestedSchema = readContext.getRequestedSchema();
+ this.fileSchema = fileSchema;
+ this.reader = new ParquetFileReader(configuration, file, blocks,
requestedSchema.getColumns());
+ for (BlockMetaData block : blocks) {
+ this.totalRowCount += block.getRowCount();
+ }
+ }
+
+ @Override
+ public Void getCurrentKey() throws IOException, InterruptedException {
+ return null;
+ }
+
+ @Override
+ public void close() throws IOException {
+ if (reader != null) {
+ reader.close();
+ reader = null;
+ }
+ }
+
+ /**
+ * Utility classes to abstract over different way to read ints with
different encodings.
+ * TODO: remove this layer of abstraction?
--- End diff --
If you use only one implementation (for example int[] backed or IntBuffer
backed) of this at a time (IE there is only one subclass loaded) then the JVM
will inline the calls the same.
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