/**
    * 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.hadoop.hbase.ipc;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  import io.netty.buffer.ByteBufOutputStream;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.BufferOverflowException;
  import java.nio.ByteBuffer;
  
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configurable;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.CellScanner;
  import org.apache.hadoop.hbase.DoNotRetryIOException;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.codec.Codec;
  import org.apache.hadoop.hbase.io.BoundedByteBufferPool;
  import org.apache.hadoop.hbase.io.ByteBufferInputStream;
  import org.apache.hadoop.hbase.io.ByteBufferOutputStream;
  import org.apache.hadoop.hbase.util.ClassSize;
  import org.apache.hadoop.io.compress.CodecPool;
  import org.apache.hadoop.io.compress.CompressionCodec;
  import org.apache.hadoop.io.compress.CompressionInputStream;
  import org.apache.hadoop.io.compress.Compressor;
  import org.apache.hadoop.io.compress.Decompressor;
  
  /**
   * Helper class for building cell block.
   */
  @InterfaceAudience.Private
  class CellBlockBuilder {
  
    // LOG is being used in TestCellBlockBuilder
    static final Log LOG = LogFactory.getLog(CellBlockBuilder.class);
  
    private final Configuration conf;
  
    /**
     * How much we think the decompressor will expand the original compressed content.
     */
    private final int cellBlockDecompressionMultiplier;
  
    private final int cellBlockBuildingInitialBufferSize;
  
    public CellBlockBuilder(Configuration conf) {
      this.conf = conf;
      this.cellBlockDecompressionMultiplier =
          conf.getInt("hbase.ipc.cellblock.decompression.buffersize.multiplier", 3);
  
      // Guess that 16k is a good size for rpc buffer. Could go bigger. See the TODO below in
      // #buildCellBlock.
      this.cellBlockBuildingInitialBufferSize =
          ClassSize.align(conf.getInt("hbase.ipc.cellblock.building.initial.buffersize", 16 * 1024));
    }
  
    private interface OutputStreamSupplier {
  
      OutputStream get(int expectedSize);
  
      int size();
    }
  
    private static final class ByteBufferOutputStreamSupplier implements OutputStreamSupplier {
  
      private ByteBufferOutputStream baos;
  
      @Override
      public OutputStream get(int expectedSize) {
        baos = new ByteBufferOutputStream(expectedSize);
        return baos;
      }
  
      @Override
      public int size() {
        return baos.size();
      }
    }
  
   /**
    * Puts CellScanner Cells into a cell block using passed in <code>codec</code> and/or
    * <code>compressor</code>.
    * @param codec
    * @param compressor
    * @param cellScanner
    * @return Null or byte buffer filled with a cellblock filled with passed-in Cells encoded using
    *         passed in <code>codec</code> and/or <code>compressor</code>; the returned buffer has
    *         been flipped and is ready for reading. Use limit to find total size.
    * @throws IOException
    */
   public ByteBuffer buildCellBlock(final Codec codec, final CompressionCodec compressor,
       final CellScanner cellScanner) throws IOException {
     ByteBufferOutputStreamSupplier supplier = new ByteBufferOutputStreamSupplier();
     if (buildCellBlock(codec, compressor, cellScanner, supplier)) {
       ByteBuffer bb = supplier.baos.getByteBuffer();
       // If no cells, don't mess around. Just return null (could be a bunch of existence checking
       // gets or something -- stuff that does not return a cell).
       return bb.hasRemaining() ? bb : null;
     } else {
       return null;
     }
   }
 
   private static final class ByteBufOutputStreamSupplier implements OutputStreamSupplier {
 
     private final ByteBufAllocator alloc;
 
     private ByteBuf buf;
 
     public ByteBufOutputStreamSupplier(ByteBufAllocator alloc) {
       this.alloc = alloc;
     }
 
     @Override
     public OutputStream get(int expectedSize) {
       buf = alloc.buffer(expectedSize);
       return new ByteBufOutputStream(buf);
     }
 
     @Override
     public int size() {
       return buf.writerIndex();
     }
   }
 
   public ByteBuf buildCellBlock(Codec codec, CompressionCodec compressor, CellScanner cellScanner,
       ByteBufAllocator alloc) throws IOException {
     ByteBufOutputStreamSupplier supplier = new ByteBufOutputStreamSupplier(alloc);
     if (buildCellBlock(codec, compressor, cellScanner, supplier)) {
       return supplier.buf;
     } else {
       return null;
     }
   }
 
   private boolean buildCellBlock(final Codec codec, final CompressionCodec compressor,
       final CellScanner cellScanner, OutputStreamSupplier supplier) throws IOException {
     if (cellScanner == null) {
       return false;
     }
     if (codec == null) {
       throw new CellScannerButNoCodecException();
     }
     int bufferSize = cellBlockBuildingInitialBufferSize;
     encodeCellsTo(supplier.get(bufferSize), cellScanner, codec, compressor);
     if (LOG.isTraceEnabled() && bufferSize < supplier.size()) {
       LOG.trace("Buffer grew from initial bufferSize=" + bufferSize + " to " + supplier.size() +
           "; up hbase.ipc.cellblock.building.initial.buffersize?");
     }
     return true;
   }
 
   private void encodeCellsTo(OutputStream os, CellScanner cellScanner, Codec codec,
       CompressionCodec compressor) throws IOException {
     Compressor poolCompressor = null;
     try {
       if (compressor != null) {
         if (compressor instanceof Configurable) {
           ((Configurable) compressor).setConf(this.conf);
         }
         poolCompressor = CodecPool.getCompressor(compressor);
         os = compressor.createOutputStream(os, poolCompressor);
       }
       Codec.Encoder encoder = codec.getEncoder(os);
       while (cellScanner.advance()) {
         encoder.write(cellScanner.current());
       }
       encoder.flush();
     } catch (BufferOverflowException | IndexOutOfBoundsException e) {
       throw new DoNotRetryIOException(e);
     } finally {
       os.close();
       if (poolCompressor != null) {
         CodecPool.returnCompressor(poolCompressor);
       }
     }
   }
 
   /**
    * Puts CellScanner Cells into a cell block using passed in <code>codec</code> and/or
    * <code>compressor</code>.
    * @param codec
    * @param compressor
    * @param cellScanner
    * @param pool Pool of ByteBuffers to make use of. Can be null and then we'll allocate our own
    *          ByteBuffer.
    * @return Null or byte buffer filled with a cellblock filled with passed-in Cells encoded using
    *         passed in <code>codec</code> and/or <code>compressor</code>; the returned buffer has
    *         been flipped and is ready for reading. Use limit to find total size. If
    *         <code>pool</code> was not null, then this returned ByteBuffer came from there and
    *         should be returned to the pool when done.
    * @throws IOException
    */
   public ByteBuffer buildCellBlock(Codec codec, CompressionCodec compressor,
       CellScanner cellScanner, BoundedByteBufferPool pool) throws IOException {
     if (cellScanner == null) {
       return null;
     }
     if (codec == null) {
       throw new CellScannerButNoCodecException();
     }
     ByteBufferOutputStream bbos;
     ByteBuffer bb = null;
     if (pool != null) {
       bb = pool.getBuffer();
       bbos = new ByteBufferOutputStream(bb);
     } else {
       bbos = new ByteBufferOutputStream(cellBlockBuildingInitialBufferSize);
     }
     encodeCellsTo(bbos, cellScanner, codec, compressor);
     if (bbos.size() == 0) {
       if (pool != null) {
         pool.putBuffer(bb);
       }
       return null;
     }
     return bbos.getByteBuffer();
   }
 
   /**
    * @param codec to use for cellblock
    * @param cellBlock to encode
    * @return CellScanner to work against the content of <code>cellBlock</code>
    * @throws IOException if encoding fails
    */
   public CellScanner createCellScanner(final Codec codec, final CompressionCodec compressor,
       final byte[] cellBlock) throws IOException {
     return createCellScanner(codec, compressor, ByteBuffer.wrap(cellBlock));
   }
 
   /**
    * @param codec
    * @param cellBlock ByteBuffer containing the cells written by the Codec. The buffer should be
    *          position()'ed at the start of the cell block and limit()'ed at the end.
    * @return CellScanner to work against the content of <code>cellBlock</code>
    * @throws IOException
    */
   public CellScanner createCellScanner(final Codec codec, final CompressionCodec compressor,
       ByteBuffer cellBlock) throws IOException {
     if (compressor != null) {
       cellBlock = decompress(compressor, cellBlock);
     }
     // Not making the Decoder over the ByteBuffer purposefully. The Decoder over the BB will
     // make Cells directly over the passed BB. This method is called at client side and we don't
     // want the Cells to share the same byte[] where the RPC response is being read. Caching of any
     // of the Cells at user's app level will make it not possible to GC the response byte[]
     return codec.getDecoder(new ByteBufferInputStream(cellBlock));
   }
 
   private ByteBuffer decompress(CompressionCodec compressor, ByteBuffer cellBlock)
       throws IOException {
     // GZIPCodec fails w/ NPE if no configuration.
     if (compressor instanceof Configurable) {
       ((Configurable) compressor).setConf(this.conf);
     }
     Decompressor poolDecompressor = CodecPool.getDecompressor(compressor);
     CompressionInputStream cis =
         compressor.createInputStream(new ByteBufferInputStream(cellBlock), poolDecompressor);
     ByteBufferOutputStream bbos;
     try {
       // TODO: This is ugly. The buffer will be resized on us if we guess wrong.
       // TODO: Reuse buffers.
       bbos =
           new ByteBufferOutputStream(cellBlock.remaining() * this.cellBlockDecompressionMultiplier);
       IOUtils.copy(cis, bbos);
       bbos.close();
       cellBlock = bbos.getByteBuffer();
     } finally {
       CodecPool.returnDecompressor(poolDecompressor);
     }
     return cellBlock;
   }
 }