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285 regels
9.5 KiB
285 regels
9.5 KiB
/* Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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Use of this source code is governed by a BSD-style license that can be
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found in the LICENSE file. See the AUTHORS file for names of contributors.
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C bindings for leveldb. May be useful as a stable ABI that can be
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used by programs that keep leveldb in a shared library, or for
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a JNI api.
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Does not support:
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. getters for the option types
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. custom comparators that implement key shortening
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. capturing post-write-snapshot
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. custom iter, db, env, cache implementations using just the C bindings
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Some conventions:
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(1) We expose just opaque struct pointers and functions to clients.
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This allows us to change internal representations without having to
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recompile clients.
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(2) For simplicity, there is no equivalent to the Slice type. Instead,
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the caller has to pass the pointer and length as separate
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arguments.
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(3) Errors are represented by a null-terminated c string. NULL
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means no error. All operations that can raise an error are passed
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a "char** errptr" as the last argument. One of the following must
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be true on entry:
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*errptr == NULL
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*errptr points to a malloc()ed null-terminated error message
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(On Windows, *errptr must have been malloc()-ed by this library.)
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On success, a leveldb routine leaves *errptr unchanged.
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On failure, leveldb frees the old value of *errptr and
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set *errptr to a malloc()ed error message.
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(4) Bools have the type unsigned char (0 == false; rest == true)
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(5) All of the pointer arguments must be non-NULL.
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*/
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#ifndef STORAGE_LEVELDB_INCLUDE_C_H_
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#define STORAGE_LEVELDB_INCLUDE_C_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stdarg.h>
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#include <stddef.h>
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#include <stdint.h>
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/* Exported types */
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typedef struct leveldb_t leveldb_t;
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typedef struct leveldb_cache_t leveldb_cache_t;
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typedef struct leveldb_comparator_t leveldb_comparator_t;
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typedef struct leveldb_env_t leveldb_env_t;
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typedef struct leveldb_filelock_t leveldb_filelock_t;
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typedef struct leveldb_filterpolicy_t leveldb_filterpolicy_t;
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typedef struct leveldb_iterator_t leveldb_iterator_t;
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typedef struct leveldb_logger_t leveldb_logger_t;
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typedef struct leveldb_options_t leveldb_options_t;
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typedef struct leveldb_randomfile_t leveldb_randomfile_t;
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typedef struct leveldb_readoptions_t leveldb_readoptions_t;
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typedef struct leveldb_seqfile_t leveldb_seqfile_t;
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typedef struct leveldb_snapshot_t leveldb_snapshot_t;
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typedef struct leveldb_writablefile_t leveldb_writablefile_t;
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typedef struct leveldb_writebatch_t leveldb_writebatch_t;
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typedef struct leveldb_writeoptions_t leveldb_writeoptions_t;
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/* DB operations */
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extern leveldb_t* leveldb_open(
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const leveldb_options_t* options,
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const char* name,
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char** errptr);
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extern void leveldb_close(leveldb_t* db);
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extern void leveldb_put(
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leveldb_t* db,
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const leveldb_writeoptions_t* options,
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const char* key, size_t keylen,
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const char* val, size_t vallen,
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char** errptr);
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extern void leveldb_delete(
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leveldb_t* db,
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const leveldb_writeoptions_t* options,
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const char* key, size_t keylen,
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char** errptr);
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extern void leveldb_write(
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leveldb_t* db,
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const leveldb_writeoptions_t* options,
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leveldb_writebatch_t* batch,
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char** errptr);
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/* Returns NULL if not found. A malloc()ed array otherwise.
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Stores the length of the array in *vallen. */
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extern char* leveldb_get(
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leveldb_t* db,
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const leveldb_readoptions_t* options,
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const char* key, size_t keylen,
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size_t* vallen,
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char** errptr);
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extern leveldb_iterator_t* leveldb_create_iterator(
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leveldb_t* db,
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const leveldb_readoptions_t* options);
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extern const leveldb_snapshot_t* leveldb_create_snapshot(
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leveldb_t* db);
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extern void leveldb_release_snapshot(
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leveldb_t* db,
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const leveldb_snapshot_t* snapshot);
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/* Returns NULL if property name is unknown.
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Else returns a pointer to a malloc()-ed null-terminated value. */
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extern char* leveldb_property_value(
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leveldb_t* db,
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const char* propname);
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extern void leveldb_approximate_sizes(
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leveldb_t* db,
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int num_ranges,
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const char* const* range_start_key, const size_t* range_start_key_len,
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const char* const* range_limit_key, const size_t* range_limit_key_len,
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uint64_t* sizes);
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extern void leveldb_compact_range(
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leveldb_t* db,
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const char* start_key, size_t start_key_len,
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const char* limit_key, size_t limit_key_len);
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/* Management operations */
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extern void leveldb_destroy_db(
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const leveldb_options_t* options,
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const char* name,
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char** errptr);
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extern void leveldb_repair_db(
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const leveldb_options_t* options,
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const char* name,
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char** errptr);
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/* Iterator */
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extern void leveldb_iter_destroy(leveldb_iterator_t*);
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extern unsigned char leveldb_iter_valid(const leveldb_iterator_t*);
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extern void leveldb_iter_seek_to_first(leveldb_iterator_t*);
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extern void leveldb_iter_seek_to_last(leveldb_iterator_t*);
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extern void leveldb_iter_seek(leveldb_iterator_t*, const char* k, size_t klen);
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extern void leveldb_iter_next(leveldb_iterator_t*);
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extern void leveldb_iter_prev(leveldb_iterator_t*);
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extern const char* leveldb_iter_key(const leveldb_iterator_t*, size_t* klen);
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extern const char* leveldb_iter_value(const leveldb_iterator_t*, size_t* vlen);
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extern void leveldb_iter_get_error(const leveldb_iterator_t*, char** errptr);
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/* Write batch */
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extern leveldb_writebatch_t* leveldb_writebatch_create();
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extern void leveldb_writebatch_destroy(leveldb_writebatch_t*);
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extern void leveldb_writebatch_clear(leveldb_writebatch_t*);
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extern void leveldb_writebatch_put(
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leveldb_writebatch_t*,
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const char* key, size_t klen,
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const char* val, size_t vlen);
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extern void leveldb_writebatch_delete(
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leveldb_writebatch_t*,
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const char* key, size_t klen);
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extern void leveldb_writebatch_iterate(
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leveldb_writebatch_t*,
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void* state,
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void (*put)(void*, const char* k, size_t klen, const char* v, size_t vlen),
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void (*deleted)(void*, const char* k, size_t klen));
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/* Options */
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extern leveldb_options_t* leveldb_options_create();
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extern void leveldb_options_destroy(leveldb_options_t*);
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extern void leveldb_options_set_comparator(
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leveldb_options_t*,
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leveldb_comparator_t*);
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extern void leveldb_options_set_filter_policy(
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leveldb_options_t*,
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leveldb_filterpolicy_t*);
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extern void leveldb_options_set_create_if_missing(
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leveldb_options_t*, unsigned char);
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extern void leveldb_options_set_error_if_exists(
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leveldb_options_t*, unsigned char);
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extern void leveldb_options_set_paranoid_checks(
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leveldb_options_t*, unsigned char);
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extern void leveldb_options_set_env(leveldb_options_t*, leveldb_env_t*);
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extern void leveldb_options_set_info_log(leveldb_options_t*, leveldb_logger_t*);
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extern void leveldb_options_set_write_buffer_size(leveldb_options_t*, size_t);
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extern void leveldb_options_set_max_open_files(leveldb_options_t*, int);
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extern void leveldb_options_set_cache(leveldb_options_t*, leveldb_cache_t*);
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extern void leveldb_options_set_block_size(leveldb_options_t*, size_t);
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extern void leveldb_options_set_block_restart_interval(leveldb_options_t*, int);
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enum {
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leveldb_no_compression = 0,
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leveldb_snappy_compression = 1
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};
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extern void leveldb_options_set_compression(leveldb_options_t*, int);
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/* Comparator */
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extern leveldb_comparator_t* leveldb_comparator_create(
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void* state,
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void (*destructor)(void*),
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int (*compare)(
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void*,
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const char* a, size_t alen,
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const char* b, size_t blen),
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const char* (*name)(void*));
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extern void leveldb_comparator_destroy(leveldb_comparator_t*);
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/* Filter policy */
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extern leveldb_filterpolicy_t* leveldb_filterpolicy_create(
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void* state,
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void (*destructor)(void*),
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char* (*create_filter)(
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void*,
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const char* const* key_array, const size_t* key_length_array,
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int num_keys,
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size_t* filter_length),
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unsigned char (*key_may_match)(
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void*,
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const char* key, size_t length,
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const char* filter, size_t filter_length),
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const char* (*name)(void*));
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extern void leveldb_filterpolicy_destroy(leveldb_filterpolicy_t*);
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extern leveldb_filterpolicy_t* leveldb_filterpolicy_create_bloom(
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int bits_per_key);
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/* Read options */
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extern leveldb_readoptions_t* leveldb_readoptions_create();
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extern void leveldb_readoptions_destroy(leveldb_readoptions_t*);
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extern void leveldb_readoptions_set_verify_checksums(
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leveldb_readoptions_t*,
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unsigned char);
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extern void leveldb_readoptions_set_fill_cache(
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leveldb_readoptions_t*, unsigned char);
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extern void leveldb_readoptions_set_snapshot(
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leveldb_readoptions_t*,
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const leveldb_snapshot_t*);
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/* Write options */
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extern leveldb_writeoptions_t* leveldb_writeoptions_create();
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extern void leveldb_writeoptions_destroy(leveldb_writeoptions_t*);
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extern void leveldb_writeoptions_set_sync(
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leveldb_writeoptions_t*, unsigned char);
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/* Cache */
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extern leveldb_cache_t* leveldb_cache_create_lru(size_t capacity);
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extern void leveldb_cache_destroy(leveldb_cache_t* cache);
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/* Env */
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extern leveldb_env_t* leveldb_create_default_env();
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extern void leveldb_env_destroy(leveldb_env_t*);
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/* Utility */
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/* Calls free(ptr).
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REQUIRES: ptr was malloc()-ed and returned by one of the routines
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in this file. Note that in certain cases (typically on Windows), you
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may need to call this routine instead of free(ptr) to dispose of
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malloc()-ed memory returned by this library. */
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extern void leveldb_free(void* ptr);
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#ifdef __cplusplus
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} /* end extern "C" */
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#endif
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#endif /* STORAGE_LEVELDB_INCLUDE_C_H_ */
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