1 /* Copyright (c) 2011 The LevelDB Authors. All rights reserved. 2 Use of this source code is governed by a BSD-style license that can be 3 found in the LICENSE file. See the AUTHORS file for names of contributors. 4 5 C bindings for leveldb. May be useful as a stable ABI that can be 6 used by programs that keep leveldb in a shared library, or for 7 a JNI api. 8 9 Does not support: 10 . getters for the option types 11 . custom comparators that implement key shortening 12 . custom iter, db, env, cache implementations using just the C bindings 13 14 Some conventions: 15 16 (1) We expose just opaque struct pointers and functions to clients. 17 This allows us to change internal representations without having to 18 recompile clients. 19 20 (2) For simplicity, there is no equivalent to the Slice type. Instead, 21 the caller has to pass the pointer and length as separate 22 arguments. 23 24 (3) Errors are represented by a null-terminated c string. NULL 25 means no error. All operations that can raise an error are passed 26 a "char** errptr" as the last argument. One of the following must 27 be true on entry: 28 *errptr == NULL 29 *errptr points to a malloc()ed null-terminated error message 30 (On Windows, *errptr must have been malloc()-ed by this library.) 31 On success, a leveldb routine leaves *errptr unchanged. 32 On failure, leveldb frees the old value of *errptr and 33 set *errptr to a malloc()ed error message. 34 35 (4) Bools have the type unsigned char (0 == false; rest == true) 36 37 (5) All of the pointer arguments must be non-NULL. 38 */ 39 40 #ifndef STORAGE_LEVELDB_INCLUDE_C_H_ 41 #define STORAGE_LEVELDB_INCLUDE_C_H_ 42 43 #ifdef __cplusplus 44 extern "C" { 45 #endif 46 47 #include <stdarg.h> 48 #include <stddef.h> 49 #include <stdint.h> 50 51 /* Exported types */ 52 53 typedef struct leveldb_t leveldb_t; 54 typedef struct leveldb_cache_t leveldb_cache_t; 55 typedef struct leveldb_comparator_t leveldb_comparator_t; 56 typedef struct leveldb_env_t leveldb_env_t; 57 typedef struct leveldb_filelock_t leveldb_filelock_t; 58 typedef struct leveldb_filterpolicy_t leveldb_filterpolicy_t; 59 typedef struct leveldb_iterator_t leveldb_iterator_t; 60 typedef struct leveldb_logger_t leveldb_logger_t; 61 typedef struct leveldb_options_t leveldb_options_t; 62 typedef struct leveldb_randomfile_t leveldb_randomfile_t; 63 typedef struct leveldb_readoptions_t leveldb_readoptions_t; 64 typedef struct leveldb_seqfile_t leveldb_seqfile_t; 65 typedef struct leveldb_snapshot_t leveldb_snapshot_t; 66 typedef struct leveldb_writablefile_t leveldb_writablefile_t; 67 typedef struct leveldb_writebatch_t leveldb_writebatch_t; 68 typedef struct leveldb_writeoptions_t leveldb_writeoptions_t; 69 70 /* DB operations */ 71 72 extern leveldb_t* leveldb_open( 73 const leveldb_options_t* options, 74 const char* name, 75 char** errptr); 76 77 extern void leveldb_close(leveldb_t* db); 78 79 extern void leveldb_put( 80 leveldb_t* db, 81 const leveldb_writeoptions_t* options, 82 const char* key, size_t keylen, 83 const char* val, size_t vallen, 84 char** errptr); 85 86 extern void leveldb_delete( 87 leveldb_t* db, 88 const leveldb_writeoptions_t* options, 89 const char* key, size_t keylen, 90 char** errptr); 91 92 extern void leveldb_write( 93 leveldb_t* db, 94 const leveldb_writeoptions_t* options, 95 leveldb_writebatch_t* batch, 96 char** errptr); 97 98 /* Returns NULL if not found. A malloc()ed array otherwise. 99 Stores the length of the array in *vallen. */ 100 extern char* leveldb_get( 101 leveldb_t* db, 102 const leveldb_readoptions_t* options, 103 const char* key, size_t keylen, 104 size_t* vallen, 105 char** errptr); 106 107 extern leveldb_iterator_t* leveldb_create_iterator( 108 leveldb_t* db, 109 const leveldb_readoptions_t* options); 110 111 extern const leveldb_snapshot_t* leveldb_create_snapshot( 112 leveldb_t* db); 113 114 extern void leveldb_release_snapshot( 115 leveldb_t* db, 116 const leveldb_snapshot_t* snapshot); 117 118 /* Returns NULL if property name is unknown. 119 Else returns a pointer to a malloc()-ed null-terminated value. */ 120 extern char* leveldb_property_value( 121 leveldb_t* db, 122 const char* propname); 123 124 extern void leveldb_approximate_sizes( 125 leveldb_t* db, 126 int num_ranges, 127 const char* const* range_start_key, const size_t* range_start_key_len, 128 const char* const* range_limit_key, const size_t* range_limit_key_len, 129 uint64_t* sizes); 130 131 extern void leveldb_compact_range( 132 leveldb_t* db, 133 const char* start_key, size_t start_key_len, 134 const char* limit_key, size_t limit_key_len); 135 136 /* Management operations */ 137 138 extern void leveldb_destroy_db( 139 const leveldb_options_t* options, 140 const char* name, 141 char** errptr); 142 143 extern void leveldb_repair_db( 144 const leveldb_options_t* options, 145 const char* name, 146 char** errptr); 147 148 /* Iterator */ 149 150 extern void leveldb_iter_destroy(leveldb_iterator_t*); 151 extern unsigned char leveldb_iter_valid(const leveldb_iterator_t*); 152 extern void leveldb_iter_seek_to_first(leveldb_iterator_t*); 153 extern void leveldb_iter_seek_to_last(leveldb_iterator_t*); 154 extern void leveldb_iter_seek(leveldb_iterator_t*, const char* k, size_t klen); 155 extern void leveldb_iter_next(leveldb_iterator_t*); 156 extern void leveldb_iter_prev(leveldb_iterator_t*); 157 extern const char* leveldb_iter_key(const leveldb_iterator_t*, size_t* klen); 158 extern const char* leveldb_iter_value(const leveldb_iterator_t*, size_t* vlen); 159 extern void leveldb_iter_get_error(const leveldb_iterator_t*, char** errptr); 160 161 /* Write batch */ 162 163 extern leveldb_writebatch_t* leveldb_writebatch_create(); 164 extern void leveldb_writebatch_destroy(leveldb_writebatch_t*); 165 extern void leveldb_writebatch_clear(leveldb_writebatch_t*); 166 extern void leveldb_writebatch_put( 167 leveldb_writebatch_t*, 168 const char* key, size_t klen, 169 const char* val, size_t vlen); 170 extern void leveldb_writebatch_delete( 171 leveldb_writebatch_t*, 172 const char* key, size_t klen); 173 extern void leveldb_writebatch_iterate( 174 leveldb_writebatch_t*, 175 void* state, 176 void (*put)(void*, const char* k, size_t klen, const char* v, size_t vlen), 177 void (*deleted)(void*, const char* k, size_t klen)); 178 179 /* Options */ 180 181 extern leveldb_options_t* leveldb_options_create(); 182 extern void leveldb_options_destroy(leveldb_options_t*); 183 extern void leveldb_options_set_comparator( 184 leveldb_options_t*, 185 leveldb_comparator_t*); 186 extern void leveldb_options_set_filter_policy( 187 leveldb_options_t*, 188 leveldb_filterpolicy_t*); 189 extern void leveldb_options_set_create_if_missing( 190 leveldb_options_t*, unsigned char); 191 extern void leveldb_options_set_error_if_exists( 192 leveldb_options_t*, unsigned char); 193 extern void leveldb_options_set_paranoid_checks( 194 leveldb_options_t*, unsigned char); 195 extern void leveldb_options_set_env(leveldb_options_t*, leveldb_env_t*); 196 extern void leveldb_options_set_info_log(leveldb_options_t*, leveldb_logger_t*); 197 extern void leveldb_options_set_write_buffer_size(leveldb_options_t*, size_t); 198 extern void leveldb_options_set_max_open_files(leveldb_options_t*, int); 199 extern void leveldb_options_set_cache(leveldb_options_t*, leveldb_cache_t*); 200 extern void leveldb_options_set_block_size(leveldb_options_t*, size_t); 201 extern void leveldb_options_set_block_restart_interval(leveldb_options_t*, int); 202 203 enum { 204 leveldb_no_compression = 0, 205 leveldb_snappy_compression = 1 206 }; 207 extern void leveldb_options_set_compression(leveldb_options_t*, int); 208 209 /* Comparator */ 210 211 extern leveldb_comparator_t* leveldb_comparator_create( 212 void* state, 213 void (*destructor)(void*), 214 int (*compare)( 215 void*, 216 const char* a, size_t alen, 217 const char* b, size_t blen), 218 const char* (*name)(void*)); 219 extern void leveldb_comparator_destroy(leveldb_comparator_t*); 220 221 /* Filter policy */ 222 223 extern leveldb_filterpolicy_t* leveldb_filterpolicy_create( 224 void* state, 225 void (*destructor)(void*), 226 char* (*create_filter)( 227 void*, 228 const char* const* key_array, const size_t* key_length_array, 229 int num_keys, 230 size_t* filter_length), 231 unsigned char (*key_may_match)( 232 void*, 233 const char* key, size_t length, 234 const char* filter, size_t filter_length), 235 const char* (*name)(void*)); 236 extern void leveldb_filterpolicy_destroy(leveldb_filterpolicy_t*); 237 238 extern leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom( 239 int bits_per_key); 240 241 /* Read options */ 242 243 extern leveldb_readoptions_t* leveldb_readoptions_create(); 244 extern void leveldb_readoptions_destroy(leveldb_readoptions_t*); 245 extern void leveldb_readoptions_set_verify_checksums( 246 leveldb_readoptions_t*, 247 unsigned char); 248 extern void leveldb_readoptions_set_fill_cache( 249 leveldb_readoptions_t*, unsigned char); 250 extern void leveldb_readoptions_set_snapshot( 251 leveldb_readoptions_t*, 252 const leveldb_snapshot_t*); 253 254 /* Write options */ 255 256 extern leveldb_writeoptions_t* leveldb_writeoptions_create(); 257 extern void leveldb_writeoptions_destroy(leveldb_writeoptions_t*); 258 extern void leveldb_writeoptions_set_sync( 259 leveldb_writeoptions_t*, unsigned char); 260 261 /* Cache */ 262 263 extern leveldb_cache_t* leveldb_cache_create_lru(size_t capacity); 264 extern void leveldb_cache_destroy(leveldb_cache_t* cache); 265 266 /* Env */ 267 268 extern leveldb_env_t* leveldb_create_default_env(); 269 extern void leveldb_env_destroy(leveldb_env_t*); 270 271 /* Utility */ 272 273 /* Calls free(ptr). 274 REQUIRES: ptr was malloc()-ed and returned by one of the routines 275 in this file. Note that in certain cases (typically on Windows), you 276 may need to call this routine instead of free(ptr) to dispose of 277 malloc()-ed memory returned by this library. */ 278 extern void leveldb_free(void* ptr); 279 280 /* Return the major version number for this release. */ 281 extern int leveldb_major_version(); 282 283 /* Return the minor version number for this release. */ 284 extern int leveldb_minor_version(); 285 286 #ifdef __cplusplus 287 } /* end extern "C" */ 288 #endif 289 290 #endif /* STORAGE_LEVELDB_INCLUDE_C_H_ */ 291