001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with this 004 * work for additional information regarding copyright ownership. The ASF 005 * licenses this file to you under the Apache License, Version 2.0 (the 006 * "License"); you may not use this file except in compliance with the License. 007 * You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 013 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 014 * License for the specific language governing permissions and limitations 015 * under the License. 016 */ 017package org.apache.hadoop.hbase.io.hfile; 018 019import java.io.DataOutputStream; 020import java.io.IOException; 021 022import org.apache.yetus.audience.InterfaceAudience; 023import org.apache.hadoop.hbase.Cell; 024import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding; 025import org.apache.hadoop.hbase.io.encoding.HFileBlockDecodingContext; 026import org.apache.hadoop.hbase.io.encoding.HFileBlockEncodingContext; 027import org.apache.hadoop.hbase.util.Bytes; 028 029/** 030 * Controls what kind of data block encoding is used. If data block encoding is 031 * not set or the given block is not a data block (encoded or not), methods 032 * should just return the unmodified block. 033 */ 034@InterfaceAudience.Private 035public interface HFileDataBlockEncoder { 036 /** Type of encoding used for data blocks in HFile. Stored in file info. */ 037 byte[] DATA_BLOCK_ENCODING = Bytes.toBytes("DATA_BLOCK_ENCODING"); 038 039 /** 040 * Starts encoding for a block of KeyValues. Call 041 * {@link #endBlockEncoding(HFileBlockEncodingContext, DataOutputStream, byte[], BlockType)} 042 * to finish encoding of a block. 043 * @param encodingCtx 044 * @param out 045 * @throws IOException 046 */ 047 void startBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out) 048 throws IOException; 049 050 /** 051 * Encodes a KeyValue. 052 * @param cell 053 * @param encodingCtx 054 * @param out 055 * @throws IOException 056 */ 057 void encode(Cell cell, HFileBlockEncodingContext encodingCtx, DataOutputStream out) 058 throws IOException; 059 060 /** 061 * Ends encoding for a block of KeyValues. Gives a chance for the encoder to do the finishing 062 * stuff for the encoded block. It must be called at the end of block encoding. 063 * @param encodingCtx 064 * @param out 065 * @param uncompressedBytesWithHeader 066 * @param blockType 067 * @throws IOException 068 */ 069 void endBlockEncoding(HFileBlockEncodingContext encodingCtx, DataOutputStream out, 070 byte[] uncompressedBytesWithHeader, BlockType blockType) throws IOException; 071 072 /** 073 * Decides whether we should use a scanner over encoded blocks. 074 * @return Whether to use encoded scanner. 075 */ 076 boolean useEncodedScanner(); 077 078 /** 079 * Save metadata in HFile which will be written to disk 080 * @param writer writer for a given HFile 081 * @exception IOException on disk problems 082 */ 083 void saveMetadata(HFile.Writer writer) 084 throws IOException; 085 086 /** @return the data block encoding */ 087 DataBlockEncoding getDataBlockEncoding(); 088 089 /** 090 * @return the effective in-cache data block encoding, taking into account 091 * whether we are doing a compaction. 092 */ 093 public DataBlockEncoding getEffectiveEncodingInCache(boolean isCompaction); 094 095 /** 096 * Create an encoder specific encoding context object for writing. And the 097 * encoding context should also perform compression if compressionAlgorithm is 098 * valid. 099 * 100 * @param headerBytes header bytes 101 * @param fileContext HFile meta data 102 * @return a new {@link HFileBlockEncodingContext} object 103 */ 104 HFileBlockEncodingContext newDataBlockEncodingContext(byte[] headerBytes, 105 HFileContext fileContext); 106 107 /** 108 * create a encoder specific decoding context for reading. And the 109 * decoding context should also do decompression if compressionAlgorithm 110 * is valid. 111 * 112 * @param fileContext - HFile meta data 113 * @return a new {@link HFileBlockDecodingContext} object 114 */ 115 HFileBlockDecodingContext newDataBlockDecodingContext(HFileContext fileContext); 116}