Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/10593#discussion_r49822023
--- Diff:
sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedRleValuesReader.java
---
@@ -0,0 +1,271 @@
+/*
+ * 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.parquet.Preconditions;
+import org.apache.parquet.bytes.BytesUtils;
+import org.apache.parquet.column.values.ValuesReader;
+import org.apache.parquet.column.values.bitpacking.BytePacker;
+import org.apache.parquet.column.values.bitpacking.Packer;
+import org.apache.parquet.io.ParquetDecodingException;
+import org.apache.spark.sql.execution.vectorized.ColumnVector;
+
+/**
+ * A values reader for Parquet's run-length encoded data. This is based
off of the version in
+ * parquet-mr with these changes:
+ * - Supports the vectorized interface.
+ * - Works on byte arrays(byte[]) instead of making byte streams.
+ *
+ * This encoding is used in multiple places:
+ * - Definition/Repetition levels
+ * - Dictionary ids.
+ */
+public final class VectorizedRleValuesReader extends ValuesReader {
+ // Current decoding mode.
+ private enum MODE {
+ RLE,
+ PACKED
+ }
+
+ // Encoded data.
+ private byte[] in;
+ private int end;
+ private int offset;
+
+ // bit/byte width of decoded data and utility to batch unpack them.
+ private int bitWidth;
+ private int bytesWidth;
+ private BytePacker packer;
+
+ // Current decoding mode and values
+ private MODE mode;
+ private int currentCount;
+ private int currentValue;
+
+ // Buffer of decoded values if the values are PACKED.
+ private int[] currentBuffer = new int[16];
+ private int currentBufferIdx = 0;
+
+ // If true, the bit width is fixed. This decoder is used in different
places and this also
+ // controls if we need to read the bitwidth from the beginning of the
data stream.
+ private final boolean fixedWidth;
+
+ public VectorizedRleValuesReader() {
+ fixedWidth = false;
+ }
+
+ public VectorizedRleValuesReader(int bitWidth) {
+ fixedWidth = true;
+ init(bitWidth);
+ }
+
+ @Override
+ public void initFromPage(int valueCount, byte[] page, int start) {
+ this.offset = start;
+ this.in = page;
+ if (fixedWidth) {
+ int length = readIntLittleEndian();
+ this.end = this.offset + length;
+ } else {
+ this.end = page.length;
+ if (this.end != this.offset) init(page[this.offset++] & 255);
+ }
+ this.currentCount = 0;
+ }
+
+ /**
+ * Initializes the internal state for decoding ints of `bitWidth`.
+ */
+ private void init(int bitWidth) {
+ Preconditions.checkArgument(bitWidth >= 0 && bitWidth <= 32, "bitWidth
must be >= 0 and <= 32");
+ this.bitWidth = bitWidth;
+ this.bytesWidth = BytesUtils.paddedByteCountFromBits(bitWidth);
+ this.packer = Packer.LITTLE_ENDIAN.newBytePacker(bitWidth);
+ }
+
+ @Override
+ public int getNextOffset() {
+ return this.end;
+ }
+
+ @Override
+ public boolean readBoolean() {
+ return this.readInteger() != 0;
+ }
+
+ @Override
+ public void skip() {
+ this.readInteger();
+ }
+
+ @Override
+ public int readValueDictionaryId() {
+ return readInteger();
+ }
+
+ @Override
+ public int readInteger() {
+ if (this.currentCount == 0) { this.readNextGroup(); }
+
+ --this.currentCount;
--- End diff --
not a big deal, but this is old c++ habit :)
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