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From paul-rogers <...@git.apache.org>
Subject [GitHub] drill pull request #611: Drill-4800: Improve parquet reader performance
Date Thu, 03 Nov 2016 18:05:58 GMT
Github user paul-rogers commented on a diff in the pull request:

    https://github.com/apache/drill/pull/611#discussion_r86397371
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/util/filereader/BufferedDirectBufInputStream.java
---
    @@ -0,0 +1,460 @@
    +/**
    + * 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
    + * <p/>
    + * http://www.apache.org/licenses/LICENSE-2.0
    + * <p/>
    + * 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.drill.exec.util.filereader;
    +
    +import com.google.common.base.Preconditions;
    +import io.netty.buffer.DrillBuf;
    +import org.apache.drill.common.config.DrillConfig;
    +import org.apache.drill.exec.memory.BufferAllocator;
    +import org.apache.drill.exec.memory.RootAllocatorFactory;
    +import org.apache.hadoop.conf.Configuration;
    +import org.apache.hadoop.fs.ByteBufferReadable;
    +import org.apache.hadoop.fs.FSDataInputStream;
    +import org.apache.hadoop.fs.FileSystem;
    +import org.apache.hadoop.fs.Path;
    +import org.apache.parquet.hadoop.Footer;
    +import org.apache.parquet.hadoop.ParquetFileReader;
    +import org.apache.parquet.hadoop.metadata.BlockMetaData;
    +import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
    +import org.apache.parquet.hadoop.util.CompatibilityUtil;
    +
    +import java.io.Closeable;
    +import java.io.IOException;
    +import java.io.InputStream;
    +import java.nio.ByteBuffer;
    +import java.util.List;
    +
    +/**
    + * <code>BufferedDirectBufInputStream</code>  reads from the
    + * underlying <code>InputStream</code> in blocks of data, into an
    + * internal buffer. The internal buffer is a direct memory backed
    + * buffer. The implementation is similar to the <code>BufferedInputStream</code>
    + * class except that the internal buffer is a Drillbuf and
    + * not a byte array. The mark and reset methods of the underlying
    + * <code>InputStream</code>are not supported.
    + */
    +public class BufferedDirectBufInputStream extends DirectBufInputStream implements Closeable
{
    +
    +  private static final org.slf4j.Logger logger =
    +      org.slf4j.LoggerFactory.getLogger(BufferedDirectBufInputStream.class);
    +
    +  private static int defaultBufferSize = 8192 * 1024; // 8 MiB
    +  private static int defaultTempBufferSize = 8192; // 8 KiB
    +
    +  /**
    +   * The internal buffer to keep data read from the underlying inputStream.
    +   * <code>internalBuffer[0]</code>  through <code>internalBuffer[count-1]
</code>
    +   * contains data read from the underlying  input stream.
    +   */
    +  protected volatile DrillBuf internalBuffer; // the internal buffer
    +
    +  /**
    +   * The number of valid bytes in <code>internalBuffer</code>.
    +   * <code> count </code> is always in the range <code>[0,internalBuffer.capacity]</code>
    +   * <code>internalBuffer[count-1]</code> is the last valid byte in the buffer.
    +   */
    +  protected int count;
    +
    +  /**
    +   * The current read position in the buffer; the index of the next
    +   * character to be read from the <code>internalBuffer</code> array.
    +   * <p>
    +   * This value is always in the range <code>[0,count]</code>.
    +   * If <code>curPosInBuffer</code> is equal to <code>count></code>
then we have read
    +   * all the buffered data and the next read (or skip) will require more data to be read
    +   * from the underlying input stream.
    +   */
    +  protected int curPosInBuffer;
    +
    +  protected long curPosInStream; // current offset in the input stream
    +
    +  private final int bufSize;
    +
    +  private volatile DrillBuf tempBuffer; // a temp Buffer for use by read(byte[] buf,
int off, int len)
    +
    +
    +  private DrillBuf getBuf() throws IOException {
    +    checkInputStreamState();
    +    if (internalBuffer == null) {
    +      throw new IOException("Input stream is closed.");
    +    }
    +    return this.internalBuffer;
    +  }
    +
    +  /**
    +   * Creates a <code>BufferedDirectBufInputStream</code>
    +   * with the default (8 MiB) buffer size.
    +   */
    +  public BufferedDirectBufInputStream(InputStream in, BufferAllocator allocator, String
id,
    +      long startOffset, long totalByteSize, boolean enableHints) {
    +    this(in, allocator, id, startOffset, totalByteSize, defaultBufferSize, enableHints);
    +  }
    +
    +  /**
    +   * Creates a <code>BufferedDirectBufInputStream</code>
    +   * with the specified buffer size.
    +   */
    +  public BufferedDirectBufInputStream(InputStream in, BufferAllocator allocator, String
id,
    +      long startOffset, long totalByteSize, int bufSize, boolean enableHints) {
    +    super(in, allocator, id, startOffset, totalByteSize, enableHints);
    +    Preconditions.checkArgument(bufSize >= 0);
    +    // We make the buffer size the smaller of the buffer Size parameter or the total
Byte Size
    +    // rounded to next highest pwoer of two
    +    int bSize = bufSize < (int) totalByteSize ? bufSize : (int) totalByteSize;
    +    // round up to next power of 2
    +    bSize--;
    +    bSize |= bSize >>> 1;
    +    bSize |= bSize >>> 2;
    +    bSize |= bSize >>> 4;
    +    bSize |= bSize >>> 8;
    +    bSize |= bSize >>> 16;
    +    bSize++;
    +    this.bufSize = bSize;
    +
    +  }
    +
    +  @Override
    +  public void init() throws UnsupportedOperationException, IOException {
    +    super.init();
    +    this.internalBuffer = this.allocator.buffer(this.bufSize);
    +    this.tempBuffer = this.allocator.buffer(defaultTempBufferSize);
    +    int bytesRead = getNextBlock();
    +    if (bytesRead <= 0) {
    +      throw new IOException("End of stream reached while initializing buffered reader.");
    +    }
    +  }
    +
    +  /**
    +   * Read one more block from the underlying stream.
    +   * Assumes we have reached the end of buffered data
    +   * Assumes it is being called from a synchronized block.
    +   * returns number of bytes read or -1 if EOF
    +   */
    +  private int getNextBlock() throws IOException {
    +    Preconditions.checkState(this.curPosInBuffer >= this.count,
    +        "Internal error: Buffered stream has not been consumed and trying to read more
from underlying stream");
    +    checkInputStreamState();
    +    DrillBuf buffer = getBuf();
    +    buffer.clear();
    +    this.count = this.curPosInBuffer = 0;
    +
    +    // We *cannot* rely on the totalByteSize being correct because
    +    // metadata for Parquet files is incorrect. So we read as
    +    // much as we can up to the size of the buffer
    +    //int bytesToRead = buffer.capacity() <= (totalByteSize + startOffset - curPosInStream
) ?
    +    //    buffer.Capacity() :
    +    //    (int) (totalByteSize + startOffset - curPosInStream );
    +    int bytesToRead = buffer.capacity();
    +
    +    ByteBuffer directBuffer = buffer.nioBuffer(curPosInBuffer, bytesToRead);
    +    // The DFS can return *more* bytes than requested if the capacity of the buffer is
greater.
    +    // i.e 'n' can be greater than bytes requested which is pretty stupid and violates
    +    // the API contract; but we still have to deal with it. So we make sure the size
of the
    +    // buffer is exactly the same as the number of bytes requested
    +    int bytesRead = -1;
    +    int nBytes = 0;
    +    if (bytesToRead > 0) {
    +      try {
    +        nBytes = CompatibilityUtil.getBuf(getInputStream(), directBuffer, bytesToRead);
    +      } catch (Exception e) {
    --- End diff --
    
    If we get an error, we log the error and continue. What happens upstream if we did not
read any new data? Does the caller turn around and try again (because the caller still needs
more bytes than are available)? Can this loop infinitely?


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