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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.hadoop.hbase.io.hfile;

import java.io.DataOutputStream;
import java.io.IOException;

import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
import org.apache.hadoop.hbase.io.encoding.EncodingState;
import org.apache.hadoop.hbase.io.encoding.HFileBlockDecodingContext;
import org.apache.hadoop.hbase.io.encoding.HFileBlockDefaultDecodingContext;
import org.apache.hadoop.hbase.io.encoding.HFileBlockDefaultEncodingContext;
import org.apache.hadoop.hbase.io.encoding.HFileBlockEncodingContext;
import org.apache.hadoop.hbase.io.encoding.NoneEncoder;

/**
 * Does not perform any kind of encoding/decoding.
 */
@InterfaceAudience.Private
public class NoOpDataBlockEncoder implements HFileDataBlockEncoder {

  public static final NoOpDataBlockEncoder INSTANCE =
      new NoOpDataBlockEncoder();

  private static class NoneEncodingState extends EncodingState {
    NoneEncoder encoder = null;
  }

  /** Cannot be instantiated. Use {@link #INSTANCE} instead. */
  private NoOpDataBlockEncoder() {
  }

  @Override
  public int encode(Cell cell, HFileBlockEncodingContext encodingCtx,
      DataOutputStream out) throws IOException {
    NoneEncodingState state = (NoneEncodingState) encodingCtx
        .getEncodingState();
    NoneEncoder encoder = state.encoder;
    return encoder.write(cell);
  }

  @Override
  public boolean useEncodedScanner() {
    return false;
  }

  @Override
  public void saveMetadata(HFile.Writer writer) {
  }

  @Override
  public DataBlockEncoding getDataBlockEncoding() {
    return DataBlockEncoding.NONE;
  }

  @Override
  public DataBlockEncoding getEffectiveEncodingInCache(boolean isCompaction) {
    return DataBlockEncoding.NONE;
  }
  
  @Override
  public String toString() {
    return getClass().getSimpleName();
  }

  @Override
  public HFileBlockEncodingContext newDataBlockEncodingContext(
      byte[] dummyHeader, HFileContext meta) {
    return new HFileBlockDefaultEncodingContext(null, dummyHeader, meta);
  }

  @Override
  public HFileBlockDecodingContext newDataBlockDecodingContext(HFileContext meta) {
    return new HFileBlockDefaultDecodingContext(meta);
  }

  @Override
  public void startBlockEncoding(HFileBlockEncodingContext blkEncodingCtx,
      DataOutputStream out) throws IOException {
    if (blkEncodingCtx.getClass() != HFileBlockDefaultEncodingContext.class) {
      throw new IOException(this.getClass().getName() + " only accepts "
          + HFileBlockDefaultEncodingContext.class.getName() + " as the "
          + "encoding context.");
    }

    HFileBlockDefaultEncodingContext encodingCtx = (HFileBlockDefaultEncodingContext) blkEncodingCtx;
    encodingCtx.prepareEncoding(out);

    NoneEncoder encoder = new NoneEncoder(out, encodingCtx);
    NoneEncodingState state = new NoneEncodingState();
    state.encoder = encoder;
    blkEncodingCtx.setEncodingState(state);
  }

  @Override
  public void endBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out,
      byte[] uncompressedBytesWithHeader, BlockType blockType) throws IOException {
    encodingCtx.postEncoding(BlockType.DATA);
  }
}