X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;ds=sidebyside;f=libraries%2Fliblmdb%2Flmdb.h;h=2ebd43f3daedf7817786deaddfb7f97821e168d9;hb=5e88fcffc20370c3f388f505f896aafdf4a52e7f;hp=b2c3861ac99bf4f1632e3c27c5e1ab52a2f89500;hpb=2a28686e4f56cf539e817661728e6c05de339eba;p=openldap diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h index b2c3861ac9..2ebd43f3da 100644 --- a/libraries/liblmdb/lmdb.h +++ b/libraries/liblmdb/lmdb.h @@ -66,6 +66,20 @@ * BSD systems or when otherwise configured with MDB_USE_POSIX_SEM. * Multiple users can cause startup to fail later, as noted above. * + * - There is normally no pure read-only mode, since readers need write + * access to locks and lock file. Exceptions: On read-only filesystems + * or with the #MDB_NOLOCK flag described under #mdb_env_open(). + * + * - By default, in versions before 0.9.10, unused portions of the data + * file might receive garbage data from memory freed by other code. + * (This does not happen when using the #MDB_WRITEMAP flag.) As of + * 0.9.10 the default behavior is to initialize such memory before + * writing to the data file. Since there may be a slight performance + * cost due to this initialization, applications may disable it using + * the #MDB_NOMEMINIT flag. Applications handling sensitive data + * which must not be written should not use this flag. This flag is + * irrelevant when using #MDB_WRITEMAP. + * * - A thread can only use one transaction at a time, plus any child * transactions. Each transaction belongs to one thread. See below. * The #MDB_NOTLS flag changes this for read-only transactions. @@ -170,7 +184,7 @@ typedef int mdb_filehandle_t; /** Library minor version */ #define MDB_VERSION_MINOR 9 /** Library patch version */ -#define MDB_VERSION_PATCH 7 +#define MDB_VERSION_PATCH 11 /** Combine args a,b,c into a single integer for easy version comparisons */ #define MDB_VERINT(a,b,c) (((a) << 24) | ((b) << 16) | (c)) @@ -180,7 +194,7 @@ typedef int mdb_filehandle_t; MDB_VERINT(MDB_VERSION_MAJOR,MDB_VERSION_MINOR,MDB_VERSION_PATCH) /** The release date of this library version */ -#define MDB_VERSION_DATE "January 10, 2013" +#define MDB_VERSION_DATE "January 15, 2014" /** A stringifier for the version info */ #define MDB_VERSTR(a,b,c,d) "MDB " #a "." #b "." #c ": (" d ")" @@ -216,13 +230,13 @@ typedef struct MDB_cursor MDB_cursor; /** @brief Generic structure used for passing keys and data in and out * of the database. * - * Key sizes must be between 1 and the liblmdb build-time constant - * #MDB_MAXKEYSIZE inclusive. This currently defaults to 511. 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. - * * Values returned from the database are valid only until a subsequent - * update operation, or the end of the transaction. + * 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 #mdb_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. */ typedef struct MDB_val { size_t mv_size; /**< size of the data item */ @@ -249,8 +263,6 @@ typedef int (MDB_cmp_func)(const MDB_val *a, const MDB_val *b); typedef void (MDB_rel_func)(MDB_val *item, void *oldptr, void *newptr, void *relctx); /** @defgroup mdb_env Environment Flags - * - * Values do not overlap Database Flags. * @{ */ /** mmap at a fixed address (experimental) */ @@ -265,15 +277,19 @@ typedef void (MDB_rel_func)(MDB_val *item, void *oldptr, void *newptr, void *rel #define MDB_NOMETASYNC 0x40000 /** use writable mmap */ #define MDB_WRITEMAP 0x80000 - /** use asynchronous msync when MDB_WRITEMAP is used */ + /** use asynchronous msync when #MDB_WRITEMAP is used */ #define MDB_MAPASYNC 0x100000 /** tie reader locktable slots to #MDB_txn objects instead of to threads */ #define MDB_NOTLS 0x200000 + /** don't do any locking, caller must manage their own locks */ +#define MDB_NOLOCK 0x400000 + /** don't do readahead (no effect on Windows) */ +#define MDB_NORDAHEAD 0x800000 + /** don't initialize malloc'd memory before writing to datafile */ +#define MDB_NOMEMINIT 0x1000000 /** @} */ /** @defgroup mdb_dbi_open Database Flags - * - * Values do not overlap Environment Flags. * @{ */ /** use reverse string keys */ @@ -486,6 +502,8 @@ int mdb_env_create(MDB_env **env); * and uses fewer mallocs, but loses protection from application bugs * like wild pointer writes and other bad updates into the database. * Incompatible with nested transactions. + * Processes with and without MDB_WRITEMAP on the same environment do + * not cooperate well. *
  • #MDB_NOMETASYNC * Flush system buffers to disk only once per transaction, omit the * metadata flush. Defer that until the system flushes files to disk, @@ -523,6 +541,38 @@ int mdb_env_create(MDB_env **env); * user threads over individual OS threads need this option. Such an * application must also serialize the write transactions in an OS * thread, since MDB'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. + * The option is not implemented on Windows. + *
  • #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 #mdb_env_set_flags(). * * @param[in] mode The UNIX permissions to set on created files. This parameter * is ignored on Windows. @@ -656,14 +706,33 @@ int mdb_env_get_flags(MDB_env *env, unsigned int *flags); */ int mdb_env_get_path(MDB_env *env, const char **path); + /** @brief Return the filedescriptor for the given environment. + * + * @param[in] env An environment handle returned by #mdb_env_create() + * @param[out] fd Address of a mdb_filehandle_t to contain the descriptor. + * @return A non-zero error value on failure and 0 on success. Some possible + * errors are: + * + */ +int mdb_env_get_fd(MDB_env *env, mdb_filehandle_t *fd); + /** @brief 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 may only be called after #mdb_env_create() and before #mdb_env_open(). - * The size may be changed by closing and reopening the environment. + * This function should be called after #mdb_env_create() and before #mdb_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. + * + * If the mapsize is changed by another process, #mdb_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. * @param[in] env An environment handle returned by #mdb_env_create() @@ -671,7 +740,8 @@ int mdb_env_get_path(MDB_env *env, const char **path); * @return A non-zero error value on failure and 0 on success. Some possible * errors are: * */ int mdb_env_set_mapsize(MDB_env *env, size_t size); @@ -723,13 +793,47 @@ int mdb_env_get_maxreaders(MDB_env *env, unsigned int *readers); */ int mdb_env_set_maxdbs(MDB_env *env, MDB_dbi dbs); - /** @brief Get the maximum size of a key for the environment. + /** @brief Get the maximum size of keys and #MDB_DUPSORT data we can write. * + * Depends on the compile-time constant #MDB_MAXKEYSIZE. Default 511. + * See @ref MDB_val. * @param[in] env An environment handle returned by #mdb_env_create() - * @return The maximum size of a key. (#MDB_MAXKEYSIZE) + * @return The maximum size of a key we can write */ int mdb_env_get_maxkeysize(MDB_env *env); + /** @brief Set application information associated with the #MDB_env. + * + * @param[in] env An environment handle returned by #mdb_env_create() + * @param[in] ctx An arbitrary pointer for whatever the application needs. + * @return A non-zero error value on failure and 0 on success. + */ +int mdb_env_set_userctx(MDB_env *env, void *ctx); + + /** @brief Get the application information associated with the #MDB_env. + * + * @param[in] env An environment handle returned by #mdb_env_create() + * @return The pointer set by #mdb_env_set_userctx(). + */ +void *mdb_env_get_userctx(MDB_env *env); + + /** @brief A callback function for most MDB assert() failures, + * called before printing the message and aborting. + * + * @param[in] env An environment handle returned by #mdb_env_create(). + * @param[in] msg The assertion message, not including newline. + */ +typedef void MDB_assert_func(MDB_env *env, const char *msg); + + /** Set or reset the assert() callback of the environment. + * Disabled if liblmdb is buillt with NDEBUG. + * @note This hack should become obsolete as lmdb's error handling matures. + * @param[in] env An environment handle returned by #mdb_env_create(). + * @parem[in] func An #MDB_assert_func function, or 0. + * @return A non-zero error value on failure and 0 on success. + */ +int mdb_env_set_assert(MDB_env *env, MDB_assert_func *func); + /** @brief Create a transaction for use with the environment. * * The transaction handle may be discarded using #mdb_txn_abort() or #mdb_txn_commit(). @@ -757,7 +861,8 @@ int mdb_env_get_maxkeysize(MDB_env *env); *
  • #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 the environment must be shut down. + * mapsize and this environment's map must be resized as well. + * See #mdb_env_set_mapsize(). *
  • #MDB_READERS_FULL - a read-only transaction was requested and * the reader lock table is full. See #mdb_env_set_maxreaders(). *
  • ENOMEM - out of memory. @@ -1085,6 +1190,8 @@ int mdb_get(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data); * 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. + * MDB does nothing else with this memory, the caller is expected + * to modify all of the space requested. *
  • #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 @@ -1330,7 +1437,7 @@ int mdb_dcmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b); * * @param[in] msg The string to be printed. * @param[in] ctx An arbitrary context pointer for the callback. - * @return < 0 on failure, 0 on success. + * @return < 0 on failure, >= 0 on success. */ typedef int (MDB_msg_func)(const char *msg, void *ctx); @@ -1339,7 +1446,7 @@ typedef int (MDB_msg_func)(const char *msg, void *ctx); * @param[in] env An environment handle returned by #mdb_env_create() * @param[in] func A #MDB_msg_func function * @param[in] ctx Anything the message function needs - * @return < 0 on failure, 0 on success. + * @return < 0 on failure, >= 0 on success. */ int mdb_reader_list(MDB_env *env, MDB_msg_func *func, void *ctx);