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 . capturing post-write-snapshot 13 . custom iter, db, env, cache implementations using just the C bindings 14 15 Some conventions: 16 17 (1) We expose just opaque struct pointers and functions to clients. 18 This allows us to change internal representations without having to 19 recompile clients. 20 21 (2) For simplicity, there is no equivalent to the Slice type. Instead, 22 the caller has to pass the pointer and length as separate 23 arguments. 24 25 (3) Errors are represented by a null-terminated c string. NULL 26 means no error. All operations that can raise an error are passed 27 a "char** errptr" as the last argument. One of the following must 28 be true on entry: 29 *errptr == NULL 30 *errptr points to a malloc()ed null-terminated error message 31 (On Windows, *errptr must have been malloc()-ed by this library.) 32 On success, a leveldb routine leaves *errptr unchanged. 33 On failure, leveldb frees the old value of *errptr and 34 set *errptr to a malloc()ed error message. 35 36 (4) Bools have the type unsigned char (0 == false; rest == true) 37 38 (5) All of the pointer arguments must be non-NULL. 39 */ 40 41 #ifndef STORAGE_LEVELDB_INCLUDE_C_H_ 42 #define STORAGE_LEVELDB_INCLUDE_C_H_ 43 44 #ifdef __cplusplus 45 extern "C" { 46 #endif 47 48 #include <stdarg.h> 49 #include <stddef.h> 50 #include <stdint.h> 51 52 /* Exported types */ 53 54 typedef struct leveldb_t leveldb_t; 55 typedef struct leveldb_cache_t leveldb_cache_t; 56 typedef struct leveldb_comparator_t leveldb_comparator_t; 57 typedef struct leveldb_env_t leveldb_env_t; 58 typedef struct leveldb_filelock_t leveldb_filelock_t; 59 typedef struct leveldb_filterpolicy_t leveldb_filterpolicy_t; 60 typedef struct leveldb_iterator_t leveldb_iterator_t; 61 typedef struct leveldb_logger_t leveldb_logger_t; 62 typedef struct leveldb_options_t leveldb_options_t; 63 typedef struct leveldb_randomfile_t leveldb_randomfile_t; 64 typedef struct leveldb_readoptions_t leveldb_readoptions_t; 65 typedef struct leveldb_seqfile_t leveldb_seqfile_t; 66 typedef struct leveldb_snapshot_t leveldb_snapshot_t; 67 typedef struct leveldb_writablefile_t leveldb_writablefile_t; 68 typedef struct leveldb_writebatch_t leveldb_writebatch_t; 69 typedef struct leveldb_writeoptions_t leveldb_writeoptions_t; 70 71 /* DB operations */ 72 73 extern leveldb_t* leveldb_open( 74 const leveldb_options_t* options, 75 const char* name, 76 char** errptr); 77 78 extern void leveldb_close(leveldb_t* db); 79 80 extern void leveldb_put( 81 leveldb_t* db, 82 const leveldb_writeoptions_t* options, 83 const char* key, size_t keylen, 84 const char* val, size_t vallen, 85 char** errptr); 86 87 extern void leveldb_delete( 88 leveldb_t* db, 89 const leveldb_writeoptions_t* options, 90 const char* key, size_t keylen, 91 char** errptr); 92 93 extern void leveldb_write( 94 leveldb_t* db, 95 const leveldb_writeoptions_t* options, 96 leveldb_writebatch_t* batch, 97 char** errptr); 98 99 /* Returns NULL if not found. A malloc()ed array otherwise. 100 Stores the length of the array in *vallen. */ 101 extern char* leveldb_get( 102 leveldb_t* db, 103 const leveldb_readoptions_t* options, 104 const char* key, size_t keylen, 105 size_t* vallen, 106 char** errptr); 107 108 extern leveldb_iterator_t* leveldb_create_iterator( 109 leveldb_t* db, 110 const leveldb_readoptions_t* options); 111 112 extern const leveldb_snapshot_t* leveldb_create_snapshot( 113 leveldb_t* db); 114 115 extern void leveldb_release_snapshot( 116 leveldb_t* db, 117 const leveldb_snapshot_t* snapshot); 118 119 /* Returns NULL if property name is unknown. 120 Else returns a pointer to a malloc()-ed null-terminated value. */ 121 extern char* leveldb_property_value( 122 leveldb_t* db, 123 const char* propname); 124 125 extern void leveldb_approximate_sizes( 126 leveldb_t* db, 127 int num_ranges, 128 const char* const* range_start_key, const size_t* range_start_key_len, 129 const char* const* range_limit_key, const size_t* range_limit_key_len, 130 uint64_t* sizes); 131 132 extern void leveldb_compact_range( 133 leveldb_t* db, 134 const char* start_key, size_t start_key_len, 135 const char* limit_key, size_t limit_key_len); 136 137 /* Management operations */ 138 139 extern void leveldb_destroy_db( 140 const leveldb_options_t* options, 141 const char* name, 142 char** errptr); 143 144 extern void leveldb_repair_db( 145 const leveldb_options_t* options, 146 const char* name, 147 char** errptr); 148 149 /* Iterator */ 150 151 extern void leveldb_iter_destroy(leveldb_iterator_t*); 152 extern unsigned char leveldb_iter_valid(const leveldb_iterator_t*); 153 extern void leveldb_iter_seek_to_first(leveldb_iterator_t*); 154 extern void leveldb_iter_seek_to_last(leveldb_iterator_t*); 155 extern void leveldb_iter_seek(leveldb_iterator_t*, const char* k, size_t klen); 156 extern void leveldb_iter_next(leveldb_iterator_t*); 157 extern void leveldb_iter_prev(leveldb_iterator_t*); 158 extern const char* leveldb_iter_key(const leveldb_iterator_t*, size_t* klen); 159 extern const char* leveldb_iter_value(const leveldb_iterator_t*, size_t* vlen); 160 extern void leveldb_iter_get_error(const leveldb_iterator_t*, char** errptr); 161 162 /* Write batch */ 163 164 extern leveldb_writebatch_t* leveldb_writebatch_create(); 165 extern void leveldb_writebatch_destroy(leveldb_writebatch_t*); 166 extern void leveldb_writebatch_clear(leveldb_writebatch_t*); 167 extern void leveldb_writebatch_put( 168 leveldb_writebatch_t*, 169 const char* key, size_t klen, 170 const char* val, size_t vlen); 171 extern void leveldb_writebatch_delete( 172 leveldb_writebatch_t*, 173 const char* key, size_t klen); 174 extern void leveldb_writebatch_iterate( 175 leveldb_writebatch_t*, 176 void* state, 177 void (*put)(void*, const char* k, size_t klen, const char* v, size_t vlen), 178 void (*deleted)(void*, const char* k, size_t klen)); 179 180 /* Options */ 181 182 extern leveldb_options_t* leveldb_options_create(); 183 extern void leveldb_options_destroy(leveldb_options_t*); 184 extern void leveldb_options_set_comparator( 185 leveldb_options_t*, 186 leveldb_comparator_t*); 187 extern void leveldb_options_set_filter_policy( 188 leveldb_options_t*, 189 leveldb_filterpolicy_t*); 190 extern void leveldb_options_set_create_if_missing( 191 leveldb_options_t*, unsigned char); 192 extern void leveldb_options_set_error_if_exists( 193 leveldb_options_t*, unsigned char); 194 extern void leveldb_options_set_paranoid_checks( 195 leveldb_options_t*, unsigned char); 196 extern void leveldb_options_set_env(leveldb_options_t*, leveldb_env_t*); 197 extern void leveldb_options_set_info_log(leveldb_options_t*, leveldb_logger_t*); 198 extern void leveldb_options_set_write_buffer_size(leveldb_options_t*, size_t); 199 extern void leveldb_options_set_max_open_files(leveldb_options_t*, int); 200 extern void leveldb_options_set_cache(leveldb_options_t*, leveldb_cache_t*); 201 extern void leveldb_options_set_block_size(leveldb_options_t*, size_t); 202 extern void leveldb_options_set_block_restart_interval(leveldb_options_t*, int); 203 204 enum { 205 leveldb_no_compression = 0, 206 leveldb_snappy_compression = 1 207 }; 208 extern void leveldb_options_set_compression(leveldb_options_t*, int); 209 210 /* Comparator */ 211 212 extern leveldb_comparator_t* leveldb_comparator_create( 213 void* state, 214 void (*destructor)(void*), 215 int (*compare)( 216 void*, 217 const char* a, size_t alen, 218 const char* b, size_t blen), 219 const char* (*name)(void*)); 220 extern void leveldb_comparator_destroy(leveldb_comparator_t*); 221 222 /* Filter policy */ 223 224 extern leveldb_filterpolicy_t* leveldb_filterpolicy_create( 225 void* state, 226 void (*destructor)(void*), 227 char* (*create_filter)( 228 void*, 229 const char* const* key_array, const size_t* key_length_array, 230 int num_keys, 231 size_t* filter_length), 232 unsigned char (*key_may_match)( 233 void*, 234 const char* key, size_t length, 235 const char* filter, size_t filter_length), 236 const char* (*name)(void*)); 237 extern void leveldb_filterpolicy_destroy(leveldb_filterpolicy_t*); 238 239 extern leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom( 240 int bits_per_key); 241 242 /* Read options */ 243 244 extern leveldb_readoptions_t* leveldb_readoptions_create(); 245 extern void leveldb_readoptions_destroy(leveldb_readoptions_t*); 246 extern void leveldb_readoptions_set_verify_checksums( 247 leveldb_readoptions_t*, 248 unsigned char); 249 extern void leveldb_readoptions_set_fill_cache( 250 leveldb_readoptions_t*, unsigned char); 251 extern void leveldb_readoptions_set_snapshot( 252 leveldb_readoptions_t*, 253 const leveldb_snapshot_t*); 254 255 /* Write options */ 256 257 extern leveldb_writeoptions_t* leveldb_writeoptions_create(); 258 extern void leveldb_writeoptions_destroy(leveldb_writeoptions_t*); 259 extern void leveldb_writeoptions_set_sync( 260 leveldb_writeoptions_t*, unsigned char); 261 262 /* Cache */ 263 264 extern leveldb_cache_t* leveldb_cache_create_lru(size_t capacity); 265 extern void leveldb_cache_destroy(leveldb_cache_t* cache); 266 267 /* Env */ 268 269 extern leveldb_env_t* leveldb_create_default_env(); 270 extern void leveldb_env_destroy(leveldb_env_t*); 271 272 /* Utility */ 273 274 /* Calls free(ptr). 275 REQUIRES: ptr was malloc()-ed and returned by one of the routines 276 in this file. Note that in certain cases (typically on Windows), you 277 may need to call this routine instead of free(ptr) to dispose of 278 malloc()-ed memory returned by this library. */ 279 extern void leveldb_free(void* ptr); 280 281 /* Return the major version number for this release. */ 282 extern int leveldb_major_version(); 283 284 /* Return the minor version number for this release. */ 285 extern int leveldb_minor_version(); 286 287 #ifdef __cplusplus 288 } /* end extern "C" */ 289 #endif 290 291 #endif /* STORAGE_LEVELDB_INCLUDE_C_H_ */ 292
