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.
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
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
16 (1) We expose just opaque struct pointers and functions to clients.
17 This allows us to change internal representations without having to
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
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
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.
35 (4) Bools have the type unsigned char (0 == false; rest == true)
37 (5) All of the pointer arguments must be non-NULL.
40 #ifndef STORAGE_LEVELDB_INCLUDE_C_H_
41 #define STORAGE_LEVELDB_INCLUDE_C_H_
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;
72 extern leveldb_t* leveldb_open(
73 const leveldb_options_t* options,
77 extern void leveldb_close(leveldb_t* db);
79 extern void leveldb_put(
81 const leveldb_writeoptions_t* options,
82 const char* key, size_t keylen,
83 const char* val, size_t vallen,
86 extern void leveldb_delete(
88 const leveldb_writeoptions_t* options,
89 const char* key, size_t keylen,
92 extern void leveldb_write(
94 const leveldb_writeoptions_t* options,
95 leveldb_writebatch_t* batch,
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(
102 const leveldb_readoptions_t* options,
103 const char* key, size_t keylen,
107 extern leveldb_iterator_t* leveldb_create_iterator(
109 const leveldb_readoptions_t* options);
111 extern const leveldb_snapshot_t* leveldb_create_snapshot(
114 extern void leveldb_release_snapshot(
116 const leveldb_snapshot_t* snapshot);
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(
122 const char* propname);
124 extern void leveldb_approximate_sizes(
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,
131 extern void leveldb_compact_range(
133 const char* start_key, size_t start_key_len,
134 const char* limit_key, size_t limit_key_len);
136 /* Management operations */
138 extern void leveldb_destroy_db(
139 const leveldb_options_t* options,
143 extern void leveldb_repair_db(
144 const leveldb_options_t* options,
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);
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*,
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));
181 extern leveldb_options_t* leveldb_options_create();
182 extern void leveldb_options_destroy(leveldb_options_t*);
183 extern void leveldb_options_set_comparator(
185 leveldb_comparator_t*);
186 extern void leveldb_options_set_filter_policy(
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);
204 leveldb_no_compression = 0,
205 leveldb_snappy_compression = 1
207 extern void leveldb_options_set_compression(leveldb_options_t*, int);
211 extern leveldb_comparator_t* leveldb_comparator_create(
213 void (*destructor)(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*);
223 extern leveldb_filterpolicy_t* leveldb_filterpolicy_create(
225 void (*destructor)(void*),
226 char* (*create_filter)(
228 const char* const* key_array, const size_t* key_length_array,
230 size_t* filter_length),
231 unsigned char (*key_may_match)(
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*);
238 extern leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom(
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*,
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*);
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);
263 extern leveldb_cache_t* leveldb_cache_create_lru(size_t capacity);
264 extern void leveldb_cache_destroy(leveldb_cache_t* cache);
268 extern leveldb_env_t* leveldb_create_default_env();
269 extern void leveldb_env_destroy(leveldb_env_t*);
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);
280 /* Return the major version number for this release. */
281 extern int leveldb_major_version();
283 /* Return the minor version number for this release. */
284 extern int leveldb_minor_version();
287 } /* end extern "C" */
290 #endif /* STORAGE_LEVELDB_INCLUDE_C_H_ */