[GitHub] [incubator-druid] clintropolis commented on a change in pull request #8950: Support orc format for native batch ingestion

[GitBox <gi...@apache.org>]

clintropolis commented on a change in pull request #8950: Support orc format for native batch ingestion
URL: https://github.com/apache/incubator-druid/pull/8950#discussion_r351060546
 
 

 ##########
 File path: extensions-core/orc-extensions/src/main/java/org/apache/druid/data/input/orc/OrcReader.java
 ##########
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+/*
+ * 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.data.input.orc;
+
+import org.apache.druid.data.input.InputEntity;
+import org.apache.druid.data.input.InputEntity.CleanableFile;
+import org.apache.druid.data.input.InputRow;
+import org.apache.druid.data.input.InputRowSchema;
+import org.apache.druid.data.input.IntermediateRowParsingReader;
+import org.apache.druid.data.input.impl.MapInputRowParser;
+import org.apache.druid.java.util.common.io.Closer;
+import org.apache.druid.java.util.common.parsers.CloseableIterator;
+import org.apache.druid.java.util.common.parsers.JSONPathSpec;
+import org.apache.druid.java.util.common.parsers.ObjectFlattener;
+import org.apache.druid.java.util.common.parsers.ObjectFlatteners;
+import org.apache.druid.java.util.common.parsers.ParseException;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.NullWritable;
+import org.apache.orc.OrcFile;
+import org.apache.orc.Reader;
+import org.apache.orc.RecordReader;
+import org.apache.orc.TypeDescription;
+import org.apache.orc.mapred.OrcMapredRecordReader;
+import org.apache.orc.mapred.OrcStruct;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+
+public class OrcReader extends IntermediateRowParsingReader<OrcStruct>
+{
+  private final Configuration conf;
+  private final InputRowSchema inputRowSchema;
+  private final InputEntity source;
+  private final File temporaryDirectory;
+  private final ObjectFlattener<OrcStruct> orcStructFlattener;
+
+  OrcReader(
+      Configuration conf,
+      InputRowSchema inputRowSchema,
+      InputEntity source,
+      File temporaryDirectory,
+      JSONPathSpec flattenSpec,
+      boolean binaryAsString
+  )
+  {
+    this.conf = conf;
+    this.inputRowSchema = inputRowSchema;
+    this.source = source;
+    this.temporaryDirectory = temporaryDirectory;
+    this.orcStructFlattener = ObjectFlatteners.create(flattenSpec, new OrcStructFlattenerMaker(binaryAsString));
+  }
+
+  @Override
+  protected CloseableIterator<OrcStruct> intermediateRowIterator() throws IOException
+  {
+    final Closer closer = Closer.create();
+
+    // We fetch here to cache a copy locally. However, this might need to be changed if we want to split an orc file
+    // into several InputSplits in the future.
+    final byte[] buffer = new byte[InputEntity.DEFAULT_FETCH_BUFFER_SIZE];
+    final CleanableFile file = closer.register(source.fetch(temporaryDirectory, buffer));
+    final Path path = new Path(file.file().toURI());
+
+    final ClassLoader currentClassLoader = Thread.currentThread().getContextClassLoader();
+    final Reader reader;
+    try {
+      Thread.currentThread().setContextClassLoader(getClass().getClassLoader());
+      reader = closer.register(OrcFile.createReader(path, OrcFile.readerOptions(conf)));
+    }
+    finally {
+      Thread.currentThread().setContextClassLoader(currentClassLoader);
+    }
+    // The below line will get the schmea to read the whole columns.
+    // This can be improved by projecting some columns only what users want in the future.
+    final TypeDescription schema = reader.getSchema();
+    final RecordReader batchReader = reader.rows(reader.options());
+    final OrcMapredRecordReader<OrcStruct> recordReader = new OrcMapredRecordReader<>(batchReader, schema);
+    closer.register(recordReader::close);
+    return new CloseableIterator<OrcStruct>()
+    {
+      final NullWritable key = recordReader.createKey();
+      OrcStruct value = null;
+
+      @Override
+      public boolean hasNext()
+      {
+        if (value == null) {
+          try {
+            // The returned OrcStruct in next() can be kept in memory for a while.
+            // Here, we create a new instance of OrcStruct before calling RecordReader.next(),
+            // so that we can avoid to share the same reference to the "value" across rows.
 
 Review comment:
   Thanks for adding a comment

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