/* * Copyright 2015-2017 Leonid Yuriev * 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 * . * * --- * * 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 * . * * --- * * Portions Copyright (c) 2009, 2010 Martin Hedenfalk * * 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 MDBX-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 path, and creates its data and lock files * under that directory. With this option, path is used as-is for * the database main data file. The database lock file is the 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 MDBX 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_ */