java/core/src/java/org/apache/orc/impl/AircompressorCodec.java

/**
 * 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.orc.impl;

import io.airlift.compress.Compressor;
import io.airlift.compress.Decompressor;
import org.apache.orc.CompressionCodec;
import org.apache.orc.CompressionKind;

import java.io.IOException;
import java.nio.ByteBuffer;

public class AircompressorCodec implements CompressionCodec {
  private final CompressionKind kind;
  private final Compressor compressor;
  private final Decompressor decompressor;

  AircompressorCodec(CompressionKind kind, Compressor compressor,
                     Decompressor decompressor) {
    this.kind = kind;
    this.compressor = compressor;
    this.decompressor = decompressor;
  }

  // Thread local buffer
  private static final ThreadLocal<byte[]> threadBuffer =
      new ThreadLocal<byte[]>() {
        @Override
        protected byte[] initialValue() {
          return null;
        }
      };

  protected static byte[] getBuffer(int size) {
    byte[] result = threadBuffer.get();
    if (result == null || result.length < size || result.length > size * 2) {
      result = new byte[size];
      threadBuffer.set(result);
    }
    return result;
  }

  @Override
  public boolean compress(ByteBuffer in, ByteBuffer out,
                          ByteBuffer overflow,
                          Options options) {
    int inBytes = in.remaining();
    // I should work on a patch for Snappy to support an overflow buffer
    // to prevent the extra buffer copy.
    byte[] compressed = getBuffer(compressor.maxCompressedLength(inBytes));
    int outBytes =
        compressor.compress(in.array(), in.arrayOffset() + in.position(), inBytes,
            compressed, 0, compressed.length);
    if (outBytes < inBytes) {
      int remaining = out.remaining();
      if (remaining >= outBytes) {
        System.arraycopy(compressed, 0, out.array(), out.arrayOffset() +
            out.position(), outBytes);
        out.position(out.position() + outBytes);
      } else {
        System.arraycopy(compressed, 0, out.array(), out.arrayOffset() +
            out.position(), remaining);
        out.position(out.limit());
        System.arraycopy(compressed, remaining, overflow.array(),
            overflow.arrayOffset(), outBytes - remaining);
        overflow.position(outBytes - remaining);
      }
      return true;
    } else {
      return false;
    }
  }

  @Override
  public void decompress(ByteBuffer in, ByteBuffer out) throws IOException {
    int inOffset = in.position();
    int uncompressLen =
        decompressor.decompress(in.array(), in.arrayOffset() + inOffset,
        in.limit() - inOffset, out.array(), out.arrayOffset() + out.position(),
            out.remaining());
    out.position(uncompressLen + out.position());
    out.flip();
  }

  private static final Options NULL_OPTION = new Options() {
    @Override
    public Options copy() {
      return this;
    }

    @Override
    public Options setSpeed(SpeedModifier newValue) {
      return this;
    }

    @Override
    public Options setData(DataKind newValue) {
      return this;
    }

    @Override
    public boolean equals(Object other) {
      return other != null && getClass() == other.getClass();
    }

    @Override
    public int hashCode() {
      return 0;
    }
  };

  @Override
  public Options getDefaultOptions() {
    return NULL_OPTION;
  }

  @Override
  public void reset() {
    // Nothing to do.
  }

  @Override
  public void destroy() {
    // Nothing to do.
  }

  @Override
  public CompressionKind getKind() {
    return kind;
  }

  @Override
  public void close() {
    OrcCodecPool.returnCodec(kind, this);
  }
}