1 /* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved. 2 3 This program is free software; you can redistribute it and/or modify 4 it under the terms of the GNU General Public License, version 2.0, 5 as published by the Free Software Foundation. 6 7 This program is also distributed with certain software (including 8 but not limited to OpenSSL) that is licensed under separate terms, 9 as designated in a particular file or component or in included license 10 documentation. The authors of MySQL hereby grant you an additional 11 permission to link the program and your derivative works with the 12 separately licensed software that they have included with MySQL. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License, version 2.0, for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program; if not, write to the Free Software 21 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ 22 23 #ifndef COMPRESSION_BASE_INCLUDED 24 #define COMPRESSION_BASE_INCLUDED 25 26 #include <cstddef> 27 #include <string> 28 #include <tuple> 29 30 namespace binary_log { 31 namespace transaction { 32 namespace compression { 33 34 const static size_t BLOCK_BYTES = 8 * 1024; 35 36 enum type { 37 /* ZSTD compression. */ 38 ZSTD = 0, 39 40 /* No compression. */ 41 NONE = 255, 42 }; 43 44 std::string type_to_string(type t); 45 46 /** 47 Base class for compressors and decompressors. 48 49 It establishes the interface and implements part of the shared 50 behavior. 51 */ 52 class Base_compressor_decompressor { 53 protected: 54 /** 55 The pointer to the buffer holding the data to compress/decompress. 56 */ 57 unsigned char *m_buffer{nullptr}; 58 59 /** 60 The buffer capacity. 61 */ 62 std::size_t m_buffer_capacity{0}; 63 64 /** 65 A cursor over the buffer. It is used internally to calculate the 66 amount of buffer used for instance. 67 */ 68 unsigned char *m_buffer_cursor{nullptr}; 69 70 public: 71 Base_compressor_decompressor(); 72 virtual ~Base_compressor_decompressor(); 73 74 /** 75 The compression algorithm type. E.g., LZ4, ZSTD, ZLIB. 76 @return the compression type. 77 */ 78 virtual type compression_type_code() = 0; 79 80 /** 81 This member function SHALL open the compressor or decompressor. 82 Every compressor/decompressor must be opened before it is utilized. 83 84 @return false on success, true otherwise 85 */ 86 virtual bool open() = 0; 87 88 /** 89 This member function SHALL close the compressor/decompressor. 90 Every compressor/decompressor MUST be closed once the stream 91 is over. 92 */ 93 virtual bool close() = 0; 94 95 /** 96 This member function returns the size of the compressed/decompressed 97 data. 98 99 @return the size of the actual data. 100 */ 101 virtual size_t size(); 102 103 /** 104 This member function returns the capacity of the buffer. 105 106 @return the capacity of the buffer. 107 */ 108 virtual std::size_t capacity(); 109 110 /** 111 This member function SHALL set the buffer into which the compressor or 112 decompressor shall write the data after it processes the stream. 113 114 @param buffer the buffer itself. 115 @param capacity the capacity of the buffer. 116 117 @return true if something went wrong, false otherwise. 118 */ 119 virtual bool set_buffer(unsigned char *buffer, std::size_t capacity); 120 121 /** 122 This member function SHALL return the buffer, the size of its data 123 and its capacity. 124 125 @return a tuple containing the buffer, size and capacity. 126 */ 127 virtual std::tuple<unsigned char *, std::size_t, std::size_t> get_buffer(); 128 129 /** 130 This member function expands the buffer by a number of bytes. 131 Expansion is aligned to the block size and it is only done if 132 needed. 133 134 @param bytes The number of bytes to expand the buffer. 135 @return false on success, true otherwise. 136 */ 137 virtual bool reserve(std::size_t bytes); 138 }; 139 140 /** 141 The base compressor abstract class. 142 143 It establishes the interface for compressors. 144 */ 145 class Compressor : public Base_compressor_decompressor { 146 public: 147 /** 148 Sets the compression level for this compressor. It is 149 only effective if done before opening the compressor. 150 After opening the compressor setting the compression 151 level, it is only effective when the compressor is 152 closed and opened again. 153 154 @param compression_level the compression level for this compressor. 155 */ 156 virtual void set_compression_level(unsigned int compression_level) = 0; 157 158 /** 159 This member function SHALL compress the data provided with the given 160 length. Note that the buffer to store the compressed data must have 161 already have been set through @c set_buffer. 162 163 If the output buffer is not large enough an error shall be returned. 164 The contents of the output buffer may still have been modified in 165 that case. 166 167 @param data the data to compress 168 @param length the length of the data. 169 170 @return a tuple containing the bytes not compressed and an error state. If 171 all bytes were decompressed, then it is returned 0 in the first 172 element and false in the second. If not all bytes were compressed, 173 it returns the number of remaining bytes not processed and false on 174 the second element. If there was an error, then the second element 175 returns true and the first elemement returns the number of bytes 176 processed until the error happened. 177 178 */ 179 virtual std::tuple<std::size_t, bool> compress(const unsigned char *data, 180 size_t length) = 0; 181 }; 182 183 /** 184 The base decompressor abstract class. 185 186 It establishes the interface for decompressors. 187 */ 188 class Decompressor : public Base_compressor_decompressor { 189 public: 190 /** 191 This member function SHALL decompress the data provided with the given 192 length. Note that the buffer to store the compressed data must have 193 already have been set through @c set_buffer. 194 195 If the output buffer is not large enough an error shall be returned. 196 The contents of the output buffer may still have been modified in 197 that case. 198 199 @param data the data to compress 200 @param length the length of the data. 201 202 @return a tuple containing the bytes not decompressed and an error state. If 203 all bytes were decompressed, then it is returned 0 in the first 204 element and false in the second. If not all bytes were decompressed, 205 it returns the number of remaining bytes not processed and false on 206 the second element. If there was an error, then the second element 207 returns true and the first elemement returns the number of bytes 208 processed until the error happened. 209 */ 210 virtual std::tuple<std::size_t, bool> decompress(const unsigned char *data, 211 size_t length) = 0; 212 }; 213 214 } // namespace compression 215 } // namespace transaction 216 } // namespace binary_log 217 218 #endif 219