001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.io.encoding;
019
020import java.nio.ByteBuffer;
021import org.apache.hadoop.hbase.KeyValue;
022import org.apache.hadoop.hbase.util.ByteBufferUtils;
023import org.apache.yetus.audience.InterfaceAudience;
024
025/**
026 * Stores the state of data block encoder at the beginning of new key.
027 */
028@InterfaceAudience.Private
029class CompressionState {
030  int keyLength;
031  int valueLength;
032
033  short rowLength;
034  int prevOffset = FIRST_KEY;
035  byte familyLength;
036  int qualifierLength;
037  byte type;
038
039  private final static int FIRST_KEY = -1;
040
041  boolean isFirst() {
042    return prevOffset == FIRST_KEY;
043  }
044
045  /**
046   * Analyze the key and fill the state. Uses mark() and reset() in ByteBuffer.
047   * @param in          Buffer at the position where key starts
048   * @param keyLength   Length of key in bytes
049   * @param valueLength Length of values in bytes
050   */
051  void readKey(ByteBuffer in, int keyLength, int valueLength) {
052    readKey(in, keyLength, valueLength, 0, null);
053  }
054
055  /**
056   * Analyze the key and fill the state assuming we know previous state. Uses mark() and reset() in
057   * ByteBuffer to avoid moving the position.
058   * <p>
059   * This method overrides all the fields of this instance, except {@link #prevOffset}, which is
060   * usually manipulated directly by encoders and decoders.
061   * @param in            Buffer at the position where key starts
062   * @param keyLength     Length of key in bytes
063   * @param valueLength   Length of values in bytes
064   * @param commonPrefix  how many first bytes are common with previous KeyValue
065   * @param previousState State from previous KeyValue
066   */
067  void readKey(ByteBuffer in, int keyLength, int valueLength, int commonPrefix,
068    CompressionState previousState) {
069    this.keyLength = keyLength;
070    this.valueLength = valueLength;
071
072    // fill the state
073    in.mark(); // mark beginning of key
074
075    if (commonPrefix < KeyValue.ROW_LENGTH_SIZE) {
076      rowLength = in.getShort();
077      ByteBufferUtils.skip(in, rowLength);
078
079      familyLength = in.get();
080
081      qualifierLength = keyLength - rowLength - familyLength - KeyValue.KEY_INFRASTRUCTURE_SIZE;
082      ByteBufferUtils.skip(in, familyLength + qualifierLength);
083    } else {
084      rowLength = previousState.rowLength;
085      familyLength = previousState.familyLength;
086      qualifierLength = previousState.qualifierLength + keyLength - previousState.keyLength;
087      ByteBufferUtils.skip(in, (KeyValue.ROW_LENGTH_SIZE + KeyValue.FAMILY_LENGTH_SIZE) + rowLength
088        + familyLength + qualifierLength);
089    }
090
091    readTimestamp(in);
092
093    type = in.get();
094
095    in.reset();
096  }
097
098  protected void readTimestamp(ByteBuffer in) {
099    // used in subclasses to add timestamp to state
100    ByteBufferUtils.skip(in, KeyValue.TIMESTAMP_SIZE);
101  }
102
103  void copyFrom(CompressionState state) {
104    keyLength = state.keyLength;
105    valueLength = state.valueLength;
106
107    rowLength = state.rowLength;
108    prevOffset = state.prevOffset;
109    familyLength = state.familyLength;
110    qualifierLength = state.qualifierLength;
111    type = state.type;
112  }
113}