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libmdbx/mdbx.h
Leo Yuriev e98a1e5319 mdbx: move MDBX_LOCK_SUFFIX to API defs.
2017-04-24 17:52:56 +03:00

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/*
* Copyright 2015-2017 Leonid Yuriev <leo@yuriev.ru>
* and other libmdbx authors: please see AUTHORS file.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted only as authorized by the OpenLDAP
* Public License.
*
* A copy of this license is available in the file LICENSE in the
* top-level directory of the distribution or, alternatively, at
* <http://www.OpenLDAP.org/license.html>.
*
* ---
*
* This code is derived from "LMDB engine" written by
* Howard Chu (Symas Corporation), which itself derived from btree.c
* written by Martin Hedenfalk.
*
* ---
*
* Portions Copyright 2011-2017 Howard Chu, Symas Corp. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted only as authorized by the OpenLDAP
* Public License.
*
* A copy of this license is available in the file LICENSE in the
* top-level directory of the distribution or, alternatively, at
* <http://www.OpenLDAP.org/license.html>.
*
* ---
*
* Portions Copyright (c) 2009, 2010 Martin Hedenfalk <martin@bzero.se>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#pragma once
/* *INDENT-OFF* */
/* clang-format off */
#ifndef _MDBX_H_
#define _MDBX_H_
#include "mdbx_osal.h"
#ifdef _MSC_VER
#pragma warning(pop)
#endif
/* *INDENT-ON* */
/* clang-format on */
#ifdef __cplusplus
extern "C" {
#endif
/** Library major version */
#define MDBX_VERSION_MAJOR 0
/** Library minor version */
#define MDBX_VERSION_MINOR 2
/** Library patch version */
#define MDBX_VERSION_PATCH 0
/** Combine args a,b,c into a single integer for easy version comparisons */
#define MDB_VERINT(a, b, c) (((a) << 24) | ((b) << 16) | (c))
/** The full library version as a single integer */
#define MDBX_VERSION_FULL \
MDB_VERINT(MDBX_VERSION_MAJOR, MDBX_VERSION_MINOR, MDBX_VERSION_PATCH)
/* The release date of this library version */
#define MDBX_VERSION_DATE "DEVEL"
/* A stringifier for the version info */
#define MDBX_VERSTR(a, b, c, d) \
"MDBX " #a "." #b "." #c ": (" d ", https://github.com/ReOpen/libmdbx)"
/* A helper for the stringifier macro */
#define MDBX_VERFOO(a, b, c, d) MDBX_VERSTR(a, b, c, d)
/* The full library version as a C string */
#define MDBX_VERSION_STRING \
MDBX_VERFOO(MDBX_VERSION_MAJOR, MDBX_VERSION_MINOR, MDBX_VERSION_PATCH, \
MDBX_VERSION_DATE)
/* The name of the lock file in the DB environment */
#define MDBX_LOCKNAME "/mdbx.lck"
/* The name of the data file in the DB environment */
#define MDBX_DATANAME "/mdbx.dat"
/* The suffix of the lock file when no subdir is used */
#define MDBX_LOCK_SUFFIX "-lck"
/* Opaque structure for a database environment.
*
* A DB environment supports multiple databases, all residing in the same
* shared-memory map.
*/
typedef struct MDB_env MDB_env;
/* Opaque structure for a transaction handle.
*
* All database operations require a transaction handle. Transactions may be
* read-only or read-write.
*/
typedef struct MDB_txn MDB_txn;
/* A handle for an individual database in the DB environment. */
typedef unsigned MDB_dbi;
/* Opaque structure for navigating through a database */
typedef struct MDB_cursor MDB_cursor;
/* Generic structure used for passing keys and data in and out
* of the database.
*
* Values returned from the database are valid only until a subsequent
* update operation, or the end of the transaction. Do not modify or
* free them, they commonly point into the database itself.
*
* Key sizes must be between 1 and mdbx_env_get_maxkeysize() inclusive.
* The same applies to data sizes in databases with the MDB_DUPSORT flag.
* Other data items can in theory be from 0 to 0xffffffff bytes long.
*/
#ifndef HAVE_STRUCT_IOVEC
struct iovec {
void *iov_base;
size_t iov_len;
};
#define HAVE_STRUCT_IOVEC
#endif /* HAVE_STRUCT_IOVEC */
typedef struct iovec MDB_val;
#define mv_size iov_len
#define mv_data iov_base
/* The maximum size of a data item.
* MDBX only store a 32 bit value for node sizes. */
#define MDBX_MAXDATASIZE INT32_MAX
/* A callback function used to compare two keys in a database */
typedef int(MDB_cmp_func)(const MDB_val *a, const MDB_val *b);
/* Environment Flags */
/* no environment directory */
#define MDB_NOSUBDIR 0x4000u
/* don't fsync after commit */
#define MDB_NOSYNC 0x10000u
/* read only */
#define MDB_RDONLY 0x20000u
/* don't fsync metapage after commit */
#define MDB_NOMETASYNC 0x40000u
/* use writable mmap */
#define MDB_WRITEMAP 0x80000u
/* use asynchronous msync when MDB_WRITEMAP is used */
#define MDB_MAPASYNC 0x100000u
/* tie reader locktable slots to MDB_txn objects instead of to threads */
#define MDB_NOTLS 0x200000u
/* don't do any locking, caller must manage their own locks
* WARNING: libmdbx don't support this mode. */
#define MDB_NOLOCK__UNSUPPORTED 0x400000u
/* don't do readahead */
#define MDB_NORDAHEAD 0x800000u
/* don't initialize malloc'd memory before writing to datafile */
#define MDB_NOMEMINIT 0x1000000u
/* aim to coalesce FreeDB records */
#define MDBX_COALESCE 0x2000000u
/* LIFO policy for reclaiming FreeDB records */
#define MDBX_LIFORECLAIM 0x4000000u
/* make a steady-sync only on close and explicit env-sync */
#define MDBX_UTTERLY_NOSYNC (MDB_NOSYNC | MDB_MAPASYNC)
/* debuging option, fill/perturb released pages */
#define MDBX_PAGEPERTURB 0x8000000u
/* Database Flags */
/* use reverse string keys */
#define MDB_REVERSEKEY 0x02u
/* use sorted duplicates */
#define MDB_DUPSORT 0x04u
/* numeric keys in native byte order, either unsigned int or mdbx_size_t.
* (lmdb expects 32-bit int <= size_t <= 32/64-bit mdbx_size_t.)
* The keys must all be of the same size. */
#define MDB_INTEGERKEY 0x08u
/* with MDB_DUPSORT, sorted dup items have fixed size */
#define MDB_DUPFIXED 0x10u
/* with MDB_DUPSORT, dups are MDB_INTEGERKEY-style integers */
#define MDB_INTEGERDUP 0x20u
/* with MDB_DUPSORT, use reverse string dups */
#define MDB_REVERSEDUP 0x40u
/* create DB if not already existing */
#define MDB_CREATE 0x40000u
/* Write Flags */
/* For put: Don't write if the key already exists. */
#define MDB_NOOVERWRITE 0x10u
/* Only for MDB_DUPSORT
* For put: don't write if the key and data pair already exist.
* For mdbx_cursor_del: remove all duplicate data items.
*/
#define MDB_NODUPDATA 0x20u
/* For mdbx_cursor_put: overwrite the current key/data pair
* MDBX allows this flag for mdbx_put() for explicit overwrite/update without
* insertion. */
#define MDB_CURRENT 0x40u
/* For put: Just reserve space for data, don't copy it. Return a
* pointer to the reserved space.
*/
#define MDB_RESERVE 0x10000u
/* Data is being appended, don't split full pages. */
#define MDB_APPEND 0x20000u
/* Duplicate data is being appended, don't split full pages. */
#define MDB_APPENDDUP 0x40000u
/* Store multiple data items in one call. Only for MDB_DUPFIXED. */
#define MDB_MULTIPLE 0x80000u
/* Copy Flags */
/* Compacting copy: Omit free space from copy, and renumber all
* pages sequentially. */
#define MDB_CP_COMPACT 1u
/* Cursor Get operations.
*
* This is the set of all operations for retrieving data
* using a cursor.
*/
typedef enum MDB_cursor_op {
MDB_FIRST, /* Position at first key/data item */
MDB_FIRST_DUP, /* Position at first data item of current key.
Only for MDB_DUPSORT */
MDB_GET_BOTH, /* Position at key/data pair. Only for MDB_DUPSORT */
MDB_GET_BOTH_RANGE, /* position at key, nearest data. Only for
MDB_DUPSORT */
MDB_GET_CURRENT, /* Return key/data at current cursor position */
MDB_GET_MULTIPLE, /* Return key and up to a page of duplicate data items
from current cursor position. Move
cursor to prepare
for MDB_NEXT_MULTIPLE. Only for
MDB_DUPFIXED */
MDB_LAST, /* Position at last key/data item */
MDB_LAST_DUP, /* Position at last data item of current key.
Only for MDB_DUPSORT */
MDB_NEXT, /* Position at next data item */
MDB_NEXT_DUP, /* Position at next data item of current key.
Only for MDB_DUPSORT */
MDB_NEXT_MULTIPLE, /* Return key and up to a page of duplicate data items
from next cursor position. Move
cursor to prepare
for MDB_NEXT_MULTIPLE. Only for
MDB_DUPFIXED */
MDB_NEXT_NODUP, /* Position at first data item of next key */
MDB_PREV, /* Position at previous data item */
MDB_PREV_DUP, /* Position at previous data item of current key.
Only for MDB_DUPSORT */
MDB_PREV_NODUP, /* Position at last data item of previous key */
MDB_SET, /* Position at specified key */
MDB_SET_KEY, /* Position at specified key, return key + data */
MDB_SET_RANGE, /* Position at first key greater than or equal to specified
key. */
MDB_PREV_MULTIPLE /* Position at previous page and return key and up to
a page of duplicate data items.
Only for MDB_DUPFIXED */
} MDB_cursor_op;
/* Return Codes
* BerkeleyDB uses -30800 to -30999, we'll go under them */
/* Successful result */
#define MDB_SUCCESS 0
#define MDBX_RESULT_FALSE MDB_SUCCESS
#define MDBX_RESULT_TRUE (-1)
/* key/data pair already exists */
#define MDB_KEYEXIST (-30799)
/* key/data pair not found (EOF) */
#define MDB_NOTFOUND (-30798)
/* Requested page not found - this usually indicates corruption */
#define MDB_PAGE_NOTFOUND (-30797)
/* Located page was wrong type */
#define MDB_CORRUPTED (-30796)
/* Update of meta page failed or environment had fatal error */
#define MDB_PANIC (-30795)
/* DB file version mismatch with libmdbx */
#define MDB_VERSION_MISMATCH (-30794)
/* File is not a valid LMDB file */
#define MDB_INVALID (-30793)
/* Environment mapsize reached */
#define MDB_MAP_FULL (-30792)
/* Environment maxdbs reached */
#define MDB_DBS_FULL (-30791)
/* Environment maxreaders reached */
#define MDB_READERS_FULL (-30790)
/* Txn has too many dirty pages */
#define MDB_TXN_FULL (-30788)
/* Cursor stack too deep - internal error */
#define MDB_CURSOR_FULL (-30787)
/* Page has not enough space - internal error */
#define MDB_PAGE_FULL (-30786)
/* Database contents grew beyond environment mapsize */
#define MDB_MAP_RESIZED (-30785)
/* Operation and DB incompatible, or DB type changed. This can mean:
* - The operation expects an MDB_DUPSORT / MDB_DUPFIXED database.
* - Opening a named DB when the unnamed DB has
*MDB_DUPSORT/MDB_INTEGERKEY.
* - Accessing a data record as a database, or vice versa.
* - The database was dropped and recreated with different flags.
*/
#define MDB_INCOMPATIBLE (-30784)
/* Invalid reuse of reader locktable slot */
#define MDB_BAD_RSLOT (-30783)
/* Transaction must abort, has a child, or is invalid */
#define MDB_BAD_TXN (-30782)
/* Unsupported size of key/DB name/data, or wrong DUPFIXED size */
#define MDB_BAD_VALSIZE (-30781)
/* The specified DBI was changed unexpectedly */
#define MDB_BAD_DBI (-30780)
/* Unexpected problem - txn should abort */
#define MDB_PROBLEM (-30779)
/* The last defined error code */
#define MDB_LAST_ERRCODE MDB_PROBLEM
/* The mdbx_put() or mdbx_replace() was called for key,
that has more that one associated value. */
#define MDBX_EMULTIVAL (-30421)
/* Bad signature of a runtime object(s), this can mean:
* - memory corruption or double-free;
* - ABI version mismatch (rare case); */
#define MDBX_EBADSIGN (-30420)
/* Statistics for a database in the environment */
typedef struct MDBX_stat {
unsigned ms_psize; /* Size of a database page.
This is currently the
same for all databases. */
unsigned ms_depth; /* Depth (height) of the B-tree */
size_t ms_branch_pages; /* Number of internal (non-leaf) pages */
size_t ms_leaf_pages; /* Number of leaf pages */
size_t ms_overflow_pages; /* Number of overflow pages */
size_t ms_entries; /* Number of data items */
} MDBX_stat;
/* Information about the environment */
typedef struct MDBX_envinfo {
void *me_mapaddr; /* Address of map, if fixed */
size_t me_mapsize; /* Size of the data memory map */
size_t me_last_pgno; /* ID of the last used page */
uint64_t me_last_txnid; /* ID of the last committed transaction */
unsigned me_maxreaders; /* max reader slots in the environment */
unsigned me_numreaders; /* max reader slots used in the environment */
uint64_t me_tail_txnid; /* ID of the last reader transaction */
uint64_t me_meta1_txnid, me_meta1_sign;
uint64_t me_meta2_txnid, me_meta2_sign;
} MDBX_envinfo;
/* Return the LMDB library version information.
*
* [out] major if non-NULL, the library major version number is copied
* here
* [out] minor if non-NULL, the library minor version number is copied
* here
* [out] patch if non-NULL, the library patch version number is copied
* here
* Returns "version string" The library version as a string
*/
LIBMDBX_API const char *mdbx_version(int *major, int *minor, int *patch);
/* Return a string describing a given error code.
*
* This function is a superset of the ANSI C X3.159-1989 (ANSI C) strerror(3)
* function. If the error code is greater than or equal to 0, then the string
* returned by the system function strerror(3) is returned. If the error code
* is less than 0, an error string corresponding to the LMDB library error is
* returned. See errors for a list of LMDB-specific error codes.
* [in] err The error code
* Returns "error message" The description of the error
*/
LIBMDBX_API const char *mdbx_strerror(int errnum);
LIBMDBX_API const char *mdbx_strerror_r(int errnum, char *buf, size_t buflen);
/* Create an LMDB environment handle.
*
* This function allocates memory for a MDB_env structure. To release
* the allocated memory and discard the handle, call mdbx_env_close().
* Before the handle may be used, it must be opened using mdbx_env_open().
* Various other options may also need to be set before opening the handle,
* e.g. mdbx_env_set_mapsize(), mdbx_env_set_maxreaders(),
* mdbx_env_set_maxdbs(),
* depending on usage requirements.
* [out] env The address where the new handle will be stored
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_create(MDB_env **env);
/* Open an environment handle.
*
* If this function fails, mdbx_env_close() must be called to discard the
*MDB_env handle.
* [in] env An environment handle returned by mdbx_env_create()
* [in] path The directory in which the database files reside. This
* directory must already exist and be writable.
* [in] flags Special options for this environment. This parameter
* must be set to 0 or by bitwise OR'ing together one or more of the
* values described here.
* Flags set by mdbx_env_set_flags() are also used.
* - MDB_NOSUBDIR
* By default, LMDB creates its environment in a directory whose
* pathname is given in \b path, and creates its data and lock
*files
* under that directory. With this option, \b path is used as-is
*for
* the database main data file. The database lock file is the \b
*path
* with "-lock" appended.
* - MDB_RDONLY
* Open the environment in read-only mode. No write operations will
*be
* allowed. LMDB will still modify the lock file - except on
*read-only
* filesystems, where LMDB does not use locks.
* - MDB_WRITEMAP
* Use a writeable memory map unless MDB_RDONLY is set. This uses
* fewer mallocs but loses protection from application bugs
* like wild pointer writes and other bad updates into the
*database.
* This may be slightly faster for DBs that fit entirely in RAM,
*but
* is slower for DBs larger than RAM.
* Incompatible with nested transactions.
* Do not mix processes with and without MDB_WRITEMAP on the same
* environment. This can defeat durability (mdbx_env_sync etc).
* - MDB_NOMETASYNC
* Flush system buffers to disk only once per transaction, omit
*the
* metadata flush. Defer that until the system flushes files to
*disk,
* or next non-MDB_RDONLY commit or mdbx_env_sync(). This
*optimization
* maintains database integrity, but a system crash may undo the
*last
* committed transaction. I.e. it preserves the ACI (atomicity,
* consistency, isolation) but not D (durability) database
*property.
* This flag may be changed at any time using
*mdbx_env_set_flags().
* - MDB_NOSYNC
* Don't flush system buffers to disk when committing a
*transaction.
* This optimization means a system crash can corrupt the database
*or
* lose the last transactions if buffers are not yet flushed to
*disk.
* The risk is governed by how often the system flushes dirty
*buffers
* to disk and how often mdbx_env_sync() is called. However, if
*the
* filesystem preserves write order and the MDB_WRITEMAP flag is
*not
* used, transactions exhibit ACI (atomicity, consistency,
*isolation)
* properties and only lose D (durability). I.e. database
*integrity
* is maintained, but a system crash may undo the final
*transactions.
* Note that (MDB_NOSYNC | MDB_WRITEMAP) leaves the system with
*no
* hint for when to write transactions to disk, unless
*mdbx_env_sync()
* is called. (MDB_MAPASYNC | MDB_WRITEMAP) may be preferable.
* This flag may be changed at any time using
*mdbx_env_set_flags().
* - MDB_MAPASYNC
* When using MDB_WRITEMAP, use asynchronous flushes to disk.
* As with MDB_NOSYNC, a system crash can then corrupt the
* database or lose the last transactions. Calling
*mdbx_env_sync()
* ensures on-disk database integrity until next commit.
* This flag may be changed at any time using
*mdbx_env_set_flags().
* - MDB_NOTLS
* Don't use Thread-Local Storage. Tie reader locktable slots to
* MDB_txn objects instead of to threads. I.e. mdbx_txn_reset()
*keeps
* the slot reseved for the MDB_txn object. A thread may use
*parallel
* read-only transactions. A read-only transaction may span threads
*if
* the user synchronizes its use. Applications that multiplex
*many
* user threads over individual OS threads need this option. Such
*an
* application must also serialize the write transactions in an
*OS
* thread, since LMDB's write locking is unaware of the user
*threads.
* - MDB_NOLOCK
* Don't do any locking. If concurrent access is anticipated, the
* caller must manage all concurrency itself. For proper
*operation
* the caller must enforce single-writer semantics, and must
*ensure
* that no readers are using old transactions while a writer is
* active. The simplest approach is to use an exclusive lock so
*that
* no readers may be active at all when a writer begins.
* - MDB_NORDAHEAD
* Turn off readahead. Most operating systems perform readahead
*on
* read requests by default. This option turns it off if the OS
* supports it. Turning it off may help random read performance
* when the DB is larger than RAM and system RAM is full.
* - MDB_NOMEMINIT
* Don't initialize malloc'd memory before writing to unused
*spaces
* in the data file. By default, memory for pages written to the
*data
* file is obtained using malloc. While these pages may be reused
*in
* subsequent transactions, freshly malloc'd pages will be
*initialized
* to zeroes before use. This avoids persisting leftover data from
*other
* code (that used the heap and subsequently freed the memory) into
*the
* data file. Note that many other system libraries may allocate
* and free memory from the heap for arbitrary uses. E.g., stdio
*may
* use the heap for file I/O buffers. This initialization step has
*a
* modest performance cost so some applications may want to
*disable
* it using this flag. This option can be a problem for
*applications
* which handle sensitive data like passwords, and it makes
*memory
* checkers like Valgrind noisy. This flag is not needed with
*MDB_WRITEMAP,
* which writes directly to the mmap instead of using malloc for
*pages. The
* initialization is also skipped if MDB_RESERVE is used; the
* caller is expected to overwrite all of the memory that was
* reserved in that case.
* This flag may be changed at any time using
*mdbx_env_set_flags().
* - #MDBX_COALESCE
* Aim to coalesce records while reclaiming FreeDB.
* This flag may be changed at any time using
*mdbx_env_set_flags().
* - #MDBX_LIFORECLAIM
* LIFO policy for reclaiming FreeDB records. This significantly
*reduce
* write IPOS in case MDB_NOSYNC with periodically checkpoints.
* [in] mode The UNIX permissions to set on created files and
*semaphores.
* This parameter is ignored on Windows.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_VERSION_MISMATCH - the version of the LMDB library doesn't
*match the
* version that created the database environment.
* - MDB_INVALID - the environment file headers are corrupted.
* - ENOENT - the directory specified by the path parameter doesn't
*exist.
* - EACCES - the user didn't have permission to access the environment
*files.
* - EAGAIN - the environment was locked by another process.
*/
LIBMDBX_API int mdbx_env_open(MDB_env *env, const char *path, unsigned flags,
mode_t mode);
LIBMDBX_API int mdbx_env_open_ex(MDB_env *env, const char *path, unsigned flags,
mode_t mode, int *exclusive);
/* Copy an LMDB environment to the specified path.
*
* This function may be used to make a backup of an existing environment.
* No lockfile is created, since it gets recreated at need.
* Note: This call can trigger significant file size growth if run in
* parallel with write transactions, because it employs a read-only
* transaction. See long-lived transactions under caveats_sec.
* [in] env An environment handle returned by mdbx_env_create(). It
* must have already been opened successfully.
* [in] path The directory in which the copy will reside. This
* directory must already exist and be writable but must otherwise be
* empty.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_copy(MDB_env *env, const char *path);
/* Copy an LMDB environment to the specified file descriptor.
*
* This function may be used to make a backup of an existing environment.
* No lockfile is created, since it gets recreated at need.
* Note: This call can trigger significant file size growth if run in
* parallel with write transactions, because it employs a read-only
* transaction. See long-lived transactions under caveats_sec.
* [in] env An environment handle returned by mdbx_env_create(). It
* must have already been opened successfully.
* [in] fd The filedescriptor to write the copy to. It must
* have already been opened for Write access.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_copyfd(MDB_env *env, mdbx_filehandle_t fd);
/* Copy an LMDB environment to the specified path, with options.
*
* This function may be used to make a backup of an existing environment.
* No lockfile is created, since it gets recreated at need.
* Note: This call can trigger significant file size growth if run in
* parallel with write transactions, because it employs a read-only
* transaction. See long-lived transactions under caveats_sec.
* [in] env An environment handle returned by mdbx_env_create(). It
* must have already been opened successfully.
* [in] path The directory in which the copy will reside. This
* directory must already exist and be writable but must otherwise be
* empty.
* [in] flags Special options for this operation. This parameter
* must be set to 0 or by bitwise OR'ing together one or more of the
* values described here.
* - MDB_CP_COMPACT - Perform compaction while copying: omit free
* pages and sequentially renumber all pages in output. This
*option
* consumes more CPU and runs more slowly than the default.
* Currently it fails if the environment has suffered a page
*leak.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_copy2(MDB_env *env, const char *path, unsigned flags);
/* Copy an LMDB environment to the specified file descriptor,
* with options.
*
* This function may be used to make a backup of an existing environment.
* No lockfile is created, since it gets recreated at need. See
* mdbx_env_copy2() for further details.
* Note: This call can trigger significant file size growth if run in
* parallel with write transactions, because it employs a read-only
* transaction. See long-lived transactions under caveats_sec.
* [in] env An environment handle returned by mdbx_env_create(). It
* must have already been opened successfully.
* [in] fd The filedescriptor to write the copy to. It must
* have already been opened for Write access.
* [in] flags Special options for this operation.
* See mdbx_env_copy2() for options.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_copyfd2(MDB_env *env, mdbx_filehandle_t fd,
unsigned flags);
/* Return statistics about the LMDB environment.
*
* [in] env An environment handle returned by mdbx_env_create()
* [out] stat The address of an MDB_stat structure
* where the statistics will be copied
*/
LIBMDBX_API int mdbx_env_stat(MDB_env *env, MDBX_stat *stat, size_t bytes);
/* Return information about the LMDB environment.
*
* [in] env An environment handle returned by mdbx_env_create()
* [out] stat The address of an MDB_envinfo structure
* where the information will be copied
*/
LIBMDBX_API int mdbx_env_info(MDB_env *env, MDBX_envinfo *info, size_t bytes);
/* Flush the data buffers to disk.
*
* Data is always written to disk when mdbx_txn_commit() is called,
* but the operating system may keep it buffered. LMDB always flushes
* the OS buffers upon commit as well, unless the environment was
* opened with MDB_NOSYNC or in part MDB_NOMETASYNC. This call is
* not valid if the environment was opened with MDB_RDONLY.
* [in] env An environment handle returned by mdbx_env_create()
* [in] force If non-zero, force a synchronous flush. Otherwise
* if the environment has the MDB_NOSYNC flag set the flushes
* will be omitted, and with MDB_MAPASYNC they will be asynchronous.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EACCES - the environment is read-only.
* - EINVAL - an invalid parameter was specified.
* - EIO - an error occurred during synchronization.
*/
LIBMDBX_API int mdbx_env_sync(MDB_env *env, int force);
/* Close the environment and release the memory map.
*
* Only a single thread may call this function. All transactions, databases,
* and cursors must already be closed before calling this function. Attempts
* to
* use any such handles after calling this function will cause a SIGSEGV.
* The environment handle will be freed and must not be used again after this
* call.
* [in] env An environment handle returned by mdbx_env_create()
* [in] dont_sync A dont'sync flag, if non-zero the last checkpoint
* (meta-page update) will be kept "as is" and may be still "weak"
* in NOSYNC/MAPASYNC modes. Such "weak" checkpoint will be ignored
* on opening next time, and transactions since the last non-weak
* checkpoint (meta-page update) will rolledback for consistency guarantee.
*/
LIBMDBX_API void mdbx_env_close(MDB_env *env);
/* Set environment flags.
*
* This may be used to set some flags in addition to those from
* mdbx_env_open(), or to unset these flags. If several threads
* change the flags at the same time, the result is undefined.
* [in] env An environment handle returned by mdbx_env_create()
* [in] flags The flags to change, bitwise OR'ed together
* [in] onoff A non-zero value sets the flags, zero clears them.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_env_set_flags(MDB_env *env, unsigned flags, int onoff);
/* Get environment flags.
*
* [in] env An environment handle returned by mdbx_env_create()
* [out] flags The address of an integer to store the flags
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_env_get_flags(MDB_env *env, unsigned *flags);
/* Return the path that was used in mdbx_env_open().
*
* [in] env An environment handle returned by mdbx_env_create()
* [out] path Address of a string pointer to contain the path. This
* is the actual string in the environment, not a copy. It should not be
* altered in any way.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_env_get_path(MDB_env *env, const char **path);
/* Return the filedescriptor for the given environment.
*
* This function may be called after fork(), so the descriptor can be
* closed before exec*(). Other LMDB file descriptors have FD_CLOEXEC.
* (Until LMDB 0.9.18, only the lockfile had that.)
*
* [in] env An environment handle returned by mdbx_env_create()
* [out] fd Address of a int to contain the descriptor.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_env_get_fd(MDB_env *env, mdbx_filehandle_t *fd);
/* Set the size of the memory map to use for this environment.
*
* The size should be a multiple of the OS page size. The default is
* 10485760 bytes. The size of the memory map is also the maximum size
* of the database. The value should be chosen as large as possible,
* to accommodate future growth of the database.
* This function should be called after mdbx_env_create() and before
*mdbx_env_open().
* It may be called at later times if no transactions are active in
* this process. Note that the library does not check for this condition,
* the caller must ensure it explicitly.
*
* The new size takes effect immediately for the current process but
* will not be persisted to any others until a write transaction has been
* committed by the current process. Also, only mapsize increases are
* persisted into the environment.
*
* If the mapsize is increased by another process, and data has grown
* beyond the range of the current mapsize, mdbx_txn_begin() will
* return MDB_MAP_RESIZED. This function may be called with a size
* of zero to adopt the new size.
*
* Any attempt to set a size smaller than the space already consumed
* by the environment will be silently changed to the current size of the used
*space.
* [in] env An environment handle returned by mdbx_env_create()
* [in] size The size in bytes
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified, or the environment
*has
* an active write transaction.
*/
LIBMDBX_API int mdbx_env_set_mapsize(MDB_env *env, size_t size);
/* Set the maximum number of threads/reader slots for the environment.
*
* This defines the number of slots in the lock table that is used to track
*readers in the
* the environment. The default is 126.
* Starting a read-only transaction normally ties a lock table slot to the
* current thread until the environment closes or the thread exits. If
* MDB_NOTLS is in use, mdbx_txn_begin() instead ties the slot to the
* MDB_txn object until it or the MDB_env object is destroyed.
* This function may only be called after mdbx_env_create() and before
*mdbx_env_open().
* [in] env An environment handle returned by mdbx_env_create()
* [in] readers The maximum number of reader lock table slots
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified, or the environment is
*already open.
*/
LIBMDBX_API int mdbx_env_set_maxreaders(MDB_env *env, unsigned readers);
/* Get the maximum number of threads/reader slots for the environment.
*
* [in] env An environment handle returned by mdbx_env_create()
* [out] readers Address of an integer to store the number of readers
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_env_get_maxreaders(MDB_env *env, unsigned *readers);
/* Set the maximum number of named databases for the environment.
*
* This function is only needed if multiple databases will be used in the
* environment. Simpler applications that use the environment as a single
* unnamed database can ignore this option.
* This function may only be called after mdbx_env_create() and before
*mdbx_env_open().
*
* Currently a moderate number of slots are cheap but a huge number gets
* expensive: 7-120 words per transaction, and every mdbx_dbi_open()
* does a linear search of the opened slots.
* [in] env An environment handle returned by mdbx_env_create()
* [in] dbs The maximum number of databases
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified, or the environment is
*already open.
*/
LIBMDBX_API int mdbx_env_set_maxdbs(MDB_env *env, MDB_dbi dbs);
/* Get the maximum size of keys and MDB_DUPSORT data we can write.
*
* [in] env An environment handle returned by mdbx_env_create()
* Returns The maximum size of a key we can write
*/
LIBMDBX_API int mdbx_env_get_maxkeysize(MDB_env *env);
LIBMDBX_API int mdbx_get_maxkeysize(size_t pagesize);
/* Set application information associated with the MDB_env.
*
* [in] env An environment handle returned by mdbx_env_create()
* [in] ctx An arbitrary pointer for whatever the application needs.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_set_userctx(MDB_env *env, void *ctx);
/* Get the application information associated with the MDB_env.
*
* [in] env An environment handle returned by mdbx_env_create()
* Returns The pointer set by mdbx_env_set_userctx().
*/
LIBMDBX_API void *mdbx_env_get_userctx(MDB_env *env);
/* A callback function for most LMDB assert() failures,
* called before printing the message and aborting.
*
* [in] env An environment handle returned by mdbx_env_create().
* [in] msg The assertion message, not including newline.
*/
typedef void MDB_assert_func(MDB_env *env, const char *msg,
const char *function, unsigned line);
/* Set or reset the assert() callback of the environment.
* Disabled if liblmdb is buillt with MDB_DEBUG=0.
* Note: This hack should become obsolete as lmdb's error handling matures.
* [in] env An environment handle returned by mdbx_env_create().
* [in] func An MDB_assert_func function, or 0.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_set_assert(MDB_env *env, MDB_assert_func *func);
/* Create a transaction for use with the environment.
*
* The transaction handle may be discarded using mdbx_txn_abort() or
*mdbx_txn_commit().
* Note: A transaction and its cursors must only be used by a single
* thread, and a thread may only have a single transaction at a time.
* If MDB_NOTLS is in use, this does not apply to read-only transactions.
* Note: Cursors may not span transactions.
* [in] env An environment handle returned by mdbx_env_create()
* [in] parent If this parameter is non-NULL, the new transaction
* will be a nested transaction, with the transaction indicated by \b parent
* as its parent. Transactions may be nested to any level. A parent
* transaction and its cursors may not issue any other operations than
* mdbx_txn_commit and mdbx_txn_abort while it has active child transactions.
* [in] flags Special options for this transaction. This parameter
* must be set to 0 or by bitwise OR'ing together one or more of the
* values described here.
* - MDB_RDONLY
* This transaction will not perform any write operations.
* [out] txn Address where the new MDB_txn handle will be stored
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_PANIC - a fatal error occurred earlier and the environment
* must be shut down.
* - MDB_MAP_RESIZED - another process wrote data beyond this
*MDB_env's
* mapsize and this environment's map must be resized as well.
* See mdbx_env_set_mapsize().
* - MDB_READERS_FULL - a read-only transaction was requested and
* the reader lock table is full. See mdbx_env_set_maxreaders().
* - ENOMEM - out of memory.
*/
LIBMDBX_API int mdbx_txn_begin(MDB_env *env, MDB_txn *parent, unsigned flags,
MDB_txn **txn);
/* Returns the transaction's MDB_env
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
*/
LIBMDBX_API MDB_env *mdbx_txn_env(MDB_txn *txn);
/* Return the transaction's ID.
*
* This returns the identifier associated with this transaction. For a
* read-only transaction, this corresponds to the snapshot being read;
* concurrent readers will frequently have the same transaction ID.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
* Returns A transaction ID, valid if input is an active transaction.
*/
LIBMDBX_API size_t mdbx_txn_id(MDB_txn *txn);
/* Commit all the operations of a transaction into the database.
*
* The transaction handle is freed. It and its cursors must not be used
* again after this call, except with mdbx_cursor_renew().
*
* Note: MDBX-mode:
* A cursor must be closed explicitly always, before
* or after its transaction ends. It can be reused with
* mdbx_cursor_renew() before finally closing it.
*
* Note: LMDB-compatible mode:
* Earlier documentation incorrectly said all cursors would be freed.
* Only write-transactions free cursors.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
* - ENOSPC - no more disk space.
* - EIO - a low-level I/O error occurred while writing.
* - ENOMEM - out of memory.
*/
LIBMDBX_API int mdbx_txn_commit(MDB_txn *txn);
/* Abandon all the operations of the transaction instead of saving
* them.
*
* The transaction handle is freed. It and its cursors must not be used
* again after this call, except with mdbx_cursor_renew().
*
* Note: MDBX-mode:
* A cursor must be closed explicitly always, before
* or after its transaction ends. It can be reused with
* mdbx_cursor_renew() before finally closing it.
*
* Note: LMDB-compatible mode:
* Earlier documentation incorrectly said all cursors would be freed.
* Only write-transactions free cursors.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
*/
LIBMDBX_API int mdbx_txn_abort(MDB_txn *txn);
/* Reset a read-only transaction.
*
* Abort the transaction like mdbx_txn_abort(), but keep the transaction
* handle. mdbx_txn_renew() may reuse the handle. This saves allocation
* overhead if the process will start a new read-only transaction soon,
* and also locking overhead if MDB_NOTLS is in use. The reader table
* lock is released, but the table slot stays tied to its thread or
* MDB_txn. Use mdbx_txn_abort() to discard a reset handle, and to free
* its lock table slot if MDB_NOTLS is in use.
* Cursors opened within the transaction must not be used
* again after this call, except with mdbx_cursor_renew().
* Reader locks generally don't interfere with writers, but they keep old
* versions of database pages allocated. Thus they prevent the old pages
* from being reused when writers commit new data, and so under heavy load
* the database size may grow much more rapidly than otherwise.
* [in] txn A transaction handle returned by mdbx_txn_begin()
*/
LIBMDBX_API int mdbx_txn_reset(MDB_txn *txn);
/* Renew a read-only transaction.
*
* This acquires a new reader lock for a transaction handle that had been
* released by mdbx_txn_reset(). It must be called before a reset transaction
* may be used again.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_PANIC - a fatal error occurred earlier and the environment
* must be shut down.
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_txn_renew(MDB_txn *txn);
/* Open a database in the environment.
* A database handle denotes the name and parameters of a database,
* independently of whether such a database exists.
* The database handle may be discarded by calling mdbx_dbi_close().
* The old database handle is returned if the database was already open.
* The handle may only be closed once.
*
* The database handle will be private to the current transaction until
* the transaction is successfully committed. If the transaction is
* aborted the handle will be closed automatically.
* After a successful commit the handle will reside in the shared
* environment, and may be used by other transactions.
*
* This function must not be called from multiple concurrent
* transactions in the same process. A transaction that uses
* this function must finish (either commit or abort) before
* any other transaction in the process may use this function.
*
* To use named databases (with name != NULL), mdbx_env_set_maxdbs()
* must be called before opening the environment. Database names are
* keys in the unnamed database, and may be read but not written.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] name The name of the database to open. If only a single
* database is needed in the environment, this value may be NULL.
* [in] flags Special options for this database. This parameter
* must be set to 0 or by bitwise OR'ing together one or more of the
* values described here.
* - MDB_REVERSEKEY
* Keys are strings to be compared in reverse order, from the end
* of the strings to the beginning. By default, Keys are treated as
*strings and
* compared from beginning to end.
* - MDB_DUPSORT
* Duplicate keys may be used in the database. (Or, from another
*perspective,
* keys may have multiple data items, stored in sorted order.) By
*default
* keys must be unique and may have only a single data item.
* - MDB_INTEGERKEY
* Keys are binary integers in native byte order, either unsigned
*int
* or mdbx_size_t, and will be sorted as such.
* (lmdb expects 32-bit int <= size_t <= 32/64-bit mdbx_size_t.)
* The keys must all be of the same size.
* - MDB_DUPFIXED
* This flag may only be used in combination with MDB_DUPSORT.
*This option
* tells the library that the data items for this database are all
*the same
* size, which allows further optimizations in storage and
*retrieval. When
* all data items are the same size, the MDB_GET_MULTIPLE,
*MDB_NEXT_MULTIPLE
* and MDB_PREV_MULTIPLE cursor operations may be used to retrieve
*multiple
* items at once.
* - MDB_INTEGERDUP
* This option specifies that duplicate data items are binary
*integers,
* similar to MDB_INTEGERKEY keys.
* - MDB_REVERSEDUP
* This option specifies that duplicate data items should be
*compared as
* strings in reverse order.
* - MDB_CREATE
* Create the named database if it doesn't exist. This option is
*not
* allowed in a read-only transaction or a read-only environment.
* [out] dbi Address where the new MDB_dbi handle will be stored
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_NOTFOUND - the specified database doesn't exist in the
*environment
* and MDB_CREATE was not specified.
* - MDB_DBS_FULL - too many databases have been opened. See
*mdbx_env_set_maxdbs().
*/
LIBMDBX_API int mdbx_dbi_open(MDB_txn *txn, const char *name, unsigned flags,
MDB_dbi *dbi);
/* Retrieve statistics for a database.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [out] stat The address of an MDB_stat structure
* where the statistics will be copied
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_dbi_stat(MDB_txn *txn, MDB_dbi dbi, MDBX_stat *stat,
size_t bytes);
/* Retrieve the DB flags for a database handle.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [out] flags Address where the flags will be returned.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_dbi_flags(MDB_txn *txn, MDB_dbi dbi, unsigned *flags);
/* Close a database handle. Normally unnecessary. Use with care:
*
* This call is not mutex protected. Handles should only be closed by
* a single thread, and only if no other threads are going to reference
* the database handle or one of its cursors any further. Do not close
* a handle if an existing transaction has modified its database.
* Doing so can cause misbehavior from database corruption to errors
* like MDB_BAD_VALSIZE (since the DB name is gone).
*
* Closing a database handle is not necessary, but lets mdbx_dbi_open()
* reuse the handle value. Usually it's better to set a bigger
* mdbx_env_set_maxdbs(), unless that value would be large.
*
* [in] env An environment handle returned by mdbx_env_create()
* [in] dbi A database handle returned by mdbx_dbi_open()
*/
LIBMDBX_API void mdbx_dbi_close(MDB_env *env, MDB_dbi dbi);
/* Empty or delete+close a database.
*
* See mdbx_dbi_close() for restrictions about closing the DB handle.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] del 0 to empty the DB, 1 to delete it from the
* environment and close the DB handle.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_drop(MDB_txn *txn, MDB_dbi dbi, int del);
/* Set a custom key comparison function for a database.
*
* The comparison function is called whenever it is necessary to compare a
* key specified by the application with a key currently stored in the
*database.
* If no comparison function is specified, and no special key flags were
*specified
* with mdbx_dbi_open(), the keys are compared lexically, with shorter keys
*collating
* before longer keys.
* Warning: This function must be called before any data access functions are
*used,
* otherwise data corruption may occur. The same comparison function must be
*used by every
* program accessing the database, every time the database is used.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] cmp A MDB_cmp_func function
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp);
/* Set a custom data comparison function for a MDB_DUPSORT database.
*
* This comparison function is called whenever it is necessary to compare a
*data
* item specified by the application with a data item currently stored in the
*database.
* This function only takes effect if the database was opened with the
*MDB_DUPSORT
* flag.
* If no comparison function is specified, and no special key flags were
*specified
* with mdbx_dbi_open(), the data items are compared lexically, with shorter
*items collating
* before longer items.
* Warning: This function must be called before any data access functions are
*used,
* otherwise data corruption may occur. The same comparison function must be
*used by every
* program accessing the database, every time the database is used.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] cmp A MDB_cmp_func function
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_set_dupsort(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp);
/* Get items from a database.
*
* This function retrieves key/data pairs from the database. The address
* and length of the data associated with the specified \b key are returned
* in the structure to which \b data refers.
* If the database supports duplicate keys (MDB_DUPSORT) then the
* first data item for the key will be returned. Retrieval of other
* items requires the use of mdbx_cursor_get().
*
* Note: The memory pointed to by the returned values is owned by the
* database. The caller need not dispose of the memory, and may not
* modify it in any way. For values returned in a read-only transaction
* any modification attempts will cause a SIGSEGV.
* Note: Values returned from the database are valid only until a
* subsequent update operation, or the end of the transaction.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] key The key to search for in the database
* [out] data The data corresponding to the key
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_NOTFOUND - the key was not in the database.
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_get(MDB_txn *txn, MDB_dbi dbi, MDB_val *key,
MDB_val *data);
/* Store items into a database.
*
* This function stores key/data pairs in the database. The default behavior
* is to enter the new key/data pair, replacing any previously existing key
* if duplicates are disallowed, or adding a duplicate data item if
* duplicates are allowed (MDB_DUPSORT).
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] key The key to store in the database
* [in,out] data The data to store
* [in] flags Special options for this operation. This parameter
* must be set to 0 or by bitwise OR'ing together one or more of the
* values described here.
* - MDB_NODUPDATA - enter the new key/data pair only if it does not
* already appear in the database. This flag may only be
*specified
* if the database was opened with MDB_DUPSORT. The function
*will
* return MDB_KEYEXIST if the key/data pair already appears in
*the
* database.
* - MDB_NOOVERWRITE - enter the new key/data pair only if the key
* does not already appear in the database. The function will
*return
* MDB_KEYEXIST if the key already appears in the database, even
*if
* the database supports duplicates (MDB_DUPSORT). The \b data
* parameter will be set to point to the existing item.
* - MDB_RESERVE - reserve space for data of the given size, but
* don't copy the given data. Instead, return a pointer to the
* reserved space, which the caller can fill in later - before
* the next update operation or the transaction ends. This saves
* an extra memcpy if the data is being generated later.
* LMDB does nothing else with this memory, the caller is
*expected
* to modify all of the space requested. This flag must not be
* specified if the database was opened with MDB_DUPSORT.
* - MDB_APPEND - append the given key/data pair to the end of the
* database. This option allows fast bulk loading when keys are
* already known to be in the correct order. Loading unsorted
*keys
* with this flag will cause a MDB_KEYEXIST error.
* - MDB_APPENDDUP - as above, but for sorted dup data.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_MAP_FULL - the database is full, see mdbx_env_set_mapsize().
* - MDB_TXN_FULL - the transaction has too many dirty pages.
* - EACCES - an attempt was made to write in a read-only transaction.
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_put(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data,
unsigned flags);
/* Delete items from a database.
*
* This function removes key/data pairs from the database.
*
* MDBX-mode:
* The data parameter is NOT ignored regardless the database does
* support sorted duplicate data items or not. If the data parameter
* is non-NULL only the matching data item will be deleted.
*
* LMDB-compatible mode:
* If the database does not support sorted duplicate data items
* (MDB_DUPSORT) the data parameter is ignored.
* If the database supports sorted duplicates and the data parameter
* is NULL, all of the duplicate data items for the key will be
* deleted. Otherwise, if the data parameter is non-NULL
* only the matching data item will be deleted.
*
* This function will return MDB_NOTFOUND if the specified key/data
* pair is not in the database.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] key The key to delete from the database
* [in] data The data to delete
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EACCES - an attempt was made to write in a read-only transaction.
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_del(MDB_txn *txn, MDB_dbi dbi, MDB_val *key,
MDB_val *data);
/* Create a cursor handle.
*
* A cursor is associated with a specific transaction and database.
* A cursor cannot be used when its database handle is closed. Nor
* when its transaction has ended, except with mdbx_cursor_renew().
* It can be discarded with mdbx_cursor_close().
*
* MDBX-mode:
* A cursor must be closed explicitly always, before
* or after its transaction ends. It can be reused with
* mdbx_cursor_renew() before finally closing it.
*
* LMDB-compatible mode:
* A cursor in a write-transaction can be closed before its transaction
* ends, and will otherwise be closed when its transaction ends.
* A cursor in a read-only transaction must be closed explicitly, before
* or after its transaction ends. It can be reused with
* mdbx_cursor_renew() before finally closing it.
* Note: Earlier documentation said that cursors in every transaction
* were closed when the transaction committed or aborted.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [out] cursor Address where the new MDB_cursor handle will be stored
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_cursor_open(MDB_txn *txn, MDB_dbi dbi,
MDB_cursor **cursor);
/* Close a cursor handle.
*
* The cursor handle will be freed and must not be used again after this call.
* Its transaction must still be live if it is a write-transaction.
* [in] cursor A cursor handle returned by mdbx_cursor_open()
*/
LIBMDBX_API void mdbx_cursor_close(MDB_cursor *cursor);
/* Renew a cursor handle.
*
* A cursor is associated with a specific transaction and database.
* Cursors that are only used in read-only
* transactions may be re-used, to avoid unnecessary malloc/free overhead.
* The cursor may be associated with a new read-only transaction, and
* referencing the same database handle as it was created with.
* This may be done whether the previous transaction is live or dead.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] cursor A cursor handle returned by mdbx_cursor_open()
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_cursor_renew(MDB_txn *txn, MDB_cursor *cursor);
/* Return the cursor's transaction handle.
*
* [in] cursor A cursor handle returned by mdbx_cursor_open()
*/
LIBMDBX_API MDB_txn *mdbx_cursor_txn(MDB_cursor *cursor);
/* Return the cursor's database handle.
*
* [in] cursor A cursor handle returned by mdbx_cursor_open()
*/
LIBMDBX_API MDB_dbi mdbx_cursor_dbi(MDB_cursor *cursor);
/* Retrieve by cursor.
*
* This function retrieves key/data pairs from the database. The address and
*length
* of the key are returned in the object to which \b key refers (except for
*the
* case of the MDB_SET option, in which the \b key object is unchanged), and
* the address and length of the data are returned in the object to which \b
*data
* refers.
* See mdbx_get() for restrictions on using the output values.
* [in] cursor A cursor handle returned by mdbx_cursor_open()
* [in,out] key The key for a retrieved item
* [in,out] data The data of a retrieved item
* [in] op A cursor operation MDB_cursor_op
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_NOTFOUND - no matching key found.
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
MDB_cursor_op op);
/* Store by cursor.
*
* This function stores key/data pairs into the database.
* The cursor is positioned at the new item, or on failure usually near it.
* Note: Earlier documentation incorrectly said errors would leave the
* state of the cursor unchanged.
* [in] cursor A cursor handle returned by mdbx_cursor_open()
* [in] key The key operated on.
* [in] data The data operated on.
* [in] flags Options for this operation. This parameter
* must be set to 0 or one of the values described here.
* - MDB_CURRENT - replace the item at the current cursor position.
* The \b key parameter must still be provided, and must match
*it.
* If using sorted duplicates (MDB_DUPSORT) the data item must
*still
* sort into the same place. This is intended to be used when the
* new data is the same size as the old. Otherwise it will simply
* perform a delete of the old record followed by an insert.
* - MDB_NODUPDATA - enter the new key/data pair only if it does not
* already appear in the database. This flag may only be
*specified
* if the database was opened with MDB_DUPSORT. The function
*will
* return MDB_KEYEXIST if the key/data pair already appears in
*the
* database.
* - MDB_NOOVERWRITE - enter the new key/data pair only if the key
* does not already appear in the database. The function will
*return
* MDB_KEYEXIST if the key already appears in the database, even
*if
* the database supports duplicates (MDB_DUPSORT).
* - MDB_RESERVE - reserve space for data of the given size, but
* don't copy the given data. Instead, return a pointer to the
* reserved space, which the caller can fill in later - before
* the next update operation or the transaction ends. This saves
* an extra memcpy if the data is being generated later. This
*flag
* must not be specified if the database was opened with
*MDB_DUPSORT.
* - MDB_APPEND - append the given key/data pair to the end of the
* database. No key comparisons are performed. This option allows
* fast bulk loading when keys are already known to be in the
* correct order. Loading unsorted keys with this flag will cause
* a MDB_KEYEXIST error.
* - MDB_APPENDDUP - as above, but for sorted dup data.
* - MDB_MULTIPLE - store multiple contiguous data elements in a
* single request. This flag may only be specified if the
*database
* was opened with MDB_DUPFIXED. The \b data argument must be an
* array of two MDB_vals. The mv_size of the first MDB_val must
*be
* the size of a single data element. The mv_data of the first
*MDB_val
* must point to the beginning of the array of contiguous data
*elements.
* The mv_size of the second MDB_val must be the count of the
*number
* of data elements to store. On return this field will be set to
* the count of the number of elements actually written. The
*mv_data
* of the second MDB_val is unused.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - MDB_MAP_FULL - the database is full, see mdbx_env_set_mapsize().
* - MDB_TXN_FULL - the transaction has too many dirty pages.
* - EACCES - an attempt was made to write in a read-only transaction.
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_cursor_put(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
unsigned flags);
/* Delete current key/data pair
*
* This function deletes the key/data pair to which the cursor refers.
* [in] cursor A cursor handle returned by mdbx_cursor_open()
* [in] flags Options for this operation. This parameter
* must be set to 0 or one of the values described here.
* - MDB_NODUPDATA - delete all of the data items for the current key.
* This flag may only be specified if the database was opened with
*MDB_DUPSORT.
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EACCES - an attempt was made to write in a read-only transaction.
* - EINVAL - an invalid parameter was specified.
*/
LIBMDBX_API int mdbx_cursor_del(MDB_cursor *cursor, unsigned flags);
/* Return count of duplicates for current key.
*
* This call is only valid on databases that support sorted duplicate
* data items MDB_DUPSORT.
* [in] cursor A cursor handle returned by mdbx_cursor_open()
* [out] countp Address where the count will be stored
* Returns A non-zero error value on failure and 0 on success. Some possible
* errors are:
* - EINVAL - cursor is not initialized, or an invalid parameter was
*specified.
*/
LIBMDBX_API int mdbx_cursor_count(MDB_cursor *cursor, size_t *countp);
/* Compare two data items according to a particular database.
*
* This returns a comparison as if the two data items were keys in the
* specified database.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] a The first item to compare
* [in] b The second item to compare
* Returns < 0 if a < b, 0 if a == b, > 0 if a > b
*/
LIBMDBX_API int mdbx_cmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a,
const MDB_val *b);
/* Compare two data items according to a particular database.
*
* This returns a comparison as if the two items were data items of
* the specified database. The database must have the MDB_DUPSORT flag.
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [in] dbi A database handle returned by mdbx_dbi_open()
* [in] a The first item to compare
* [in] b The second item to compare
* Returns < 0 if a < b, 0 if a == b, > 0 if a > b
*/
LIBMDBX_API int mdbx_dcmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a,
const MDB_val *b);
/* A callback function used to print a message from the library.
*
* [in] msg The string to be printed.
* [in] ctx An arbitrary context pointer for the callback.
* Returns < 0 on failure, >= 0 on success.
*/
typedef int(MDB_msg_func)(const char *msg, void *ctx);
/* Dump the entries in the reader lock table.
*
* [in] env An environment handle returned by mdbx_env_create()
* [in] func A MDB_msg_func function
* [in] ctx Anything the message function needs
* Returns < 0 on failure, >= 0 on success.
*/
LIBMDBX_API int mdbx_reader_list(MDB_env *env, MDB_msg_func *func, void *ctx);
/* Check for stale entries in the reader lock table.
*
* [in] env An environment handle returned by mdbx_env_create()
* [out] dead Number of stale slots that were cleared
* Returns 0 on success, non-zero on failure.
*/
LIBMDBX_API int mdbx_reader_check(MDB_env *env, int *dead);
LIBMDBX_API char *mdbx_dkey(MDB_val *key, char *buf, const size_t bufsize);
LIBMDBX_API int mdbx_env_close_ex(MDB_env *env, int dont_sync);
/* Set threshold to force flush the data buffers to disk,
* even of MDB_NOSYNC, MDB_NOMETASYNC and MDB_MAPASYNC flags
* in the environment.
*
* Data is always written to disk when mdbx_txn_commit() is called,
* but the operating system may keep it buffered. LMDB always flushes
* the OS buffers upon commit as well, unless the environment was
* opened with MDB_NOSYNC or in part MDB_NOMETASYNC.
*
* The default is 0, than mean no any threshold checked,
* and no additional flush will be made.
*
* [in] env An environment handle returned by mdbx_env_create()
* [in] bytes The size in bytes of summary changes
* when a synchronous flush would be made.
* Returns A non-zero error value on failure and 0 on success.
*/
LIBMDBX_API int mdbx_env_set_syncbytes(MDB_env *env, size_t bytes);
/* Returns a lag of the reading.
*
* Returns an information for estimate how much given read-only
* transaction is lagging relative the to actual head.
*
* [in] txn A transaction handle returned by mdbx_txn_begin()
* [out] percent Percentage of page allocation in the database.
* Returns Number of transactions committed after the given was started for
* read, or -1 on failure.
*/
LIBMDBX_API int mdbx_txn_straggler(MDB_txn *txn, int *percent);
/* A callback function for killing a laggard readers,
* but also could waiting ones. Called in case of MDB_MAP_FULL error.
*
* [in] env An environment handle returned by mdbx_env_create().
* [in] pid pid of the reader process.
* [in] thread_id thread_id of the reader thread.
* [in] txn Transaction number on which stalled.
* [in] gap a lag from the last commited txn.
* [in] retry a retry number, less that zero for notify end of OOM-loop.
* Returns -1 on failure (reader is not killed),
* 0 on a race condition (no such reader),
* 1 on success (reader was killed),
* >1 on success (reader was SURE killed).
*/
typedef int(MDBX_oom_func)(MDB_env *env, int pid, mdbx_tid_t thread_id,
size_t txn, unsigned gap, int retry);
/* Set the OOM callback.
*
* Callback will be called only on out-of-pages case for killing
* a laggard readers to allowing reclaiming of freeDB.
*
* [in] env An environment handle returned by mdbx_env_create().
* [in] oomfunc A #MDBX_oom_func function or NULL to disable.
*/
LIBMDBX_API void mdbx_env_set_oomfunc(MDB_env *env, MDBX_oom_func *oom_func);
/* Get the current oom_func callback.
*
* Callback will be called only on out-of-pages case for killing
* a laggard readers to allowing reclaiming of freeDB.
*
* [in] env An environment handle returned by mdbx_env_create().
* Returns A #MDBX_oom_func function or NULL if disabled.
*/
LIBMDBX_API MDBX_oom_func *mdbx_env_get_oomfunc(MDB_env *env);
#define MDBX_DBG_ASSERT 1
#define MDBX_DBG_PRINT 2
#define MDBX_DBG_TRACE 4
#define MDBX_DBG_EXTRA 8
#define MDBX_DBG_AUDIT 16
#define MDBX_DBG_EDGE 32
/* LY: a "don't touch" value */
#define MDBX_DBG_DNT (-1L)
typedef void MDBX_debug_func(int type, const char *function, int line,
const char *msg, va_list args);
LIBMDBX_API int mdbx_setup_debug(int flags, MDBX_debug_func *logger,
long edge_txn);
typedef int MDBX_pgvisitor_func(size_t pgno, unsigned pgnumber, void *ctx,
const char *dbi, const char *type, int nentries,
int payload_bytes, int header_bytes,
int unused_bytes);
LIBMDBX_API int mdbx_env_pgwalk(MDB_txn *txn, MDBX_pgvisitor_func *visitor,
void *ctx);
typedef struct mdbx_canary { uint64_t x, y, z, v; } mdbx_canary;
LIBMDBX_API int mdbx_canary_put(MDB_txn *txn, const mdbx_canary *canary);
LIBMDBX_API int mdbx_canary_get(MDB_txn *txn, mdbx_canary *canary);
/* Returns:
* - MDBX_RESULT_TRUE when no more data available
* or cursor not positioned;
* - MDBX_RESULT_FALSE when data available;
* - Otherwise the error code. */
LIBMDBX_API int mdbx_cursor_eof(MDB_cursor *mc);
/* Returns: MDBX_RESULT_TRUE, MDBX_RESULT_FALSE or Error code. */
LIBMDBX_API int mdbx_cursor_on_first(MDB_cursor *mc);
/* Returns: MDBX_RESULT_TRUE, MDBX_RESULT_FALSE or Error code. */
LIBMDBX_API int mdbx_cursor_on_last(MDB_cursor *mc);
LIBMDBX_API int mdbx_replace(MDB_txn *txn, MDB_dbi dbi, MDB_val *key,
MDB_val *new_data, MDB_val *old_data,
unsigned flags);
/* Same as mdbx_get(), but:
* 1) if values_count is not NULL, then returns the count
* of multi-values/duplicates for a given key.
* 2) updates the key for pointing to the actual key's data inside DB. */
LIBMDBX_API int mdbx_get_ex(MDB_txn *txn, MDB_dbi dbi, MDB_val *key,
MDB_val *data, int *values_count);
LIBMDBX_API int mdbx_is_dirty(const MDB_txn *txn, const void *ptr);
LIBMDBX_API int mdbx_dbi_open_ex(MDB_txn *txn, const char *name, unsigned flags,
MDB_dbi *dbi, MDB_cmp_func *keycmp,
MDB_cmp_func *datacmp);
LIBMDBX_API int mdbx_dbi_sequence(MDB_txn *txn, MDB_dbi dbi, uint64_t *result,
uint64_t increment);
#ifdef __cplusplus
}
#endif
#ifdef _MSC_VER
#pragma warning(pop)
#endif
#endif /* _MDBX_H_ */
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