X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=libraries%2Flibmdb%2Fmdb.h;h=9075c41e0c6d929f0556fdca2aed1d9df7e348dd;hb=68143e4532ba3b3dccdb4e80665140542170d6d6;hp=4a57ba02e2edd084f611ef85264d21fc2970644b;hpb=e91dae3ed52ea2ced5d747b3ab95534c957c8e6d;p=openldap diff --git a/libraries/libmdb/mdb.h b/libraries/libmdb/mdb.h index 4a57ba02e2..9075c41e0c 100644 --- a/libraries/libmdb/mdb.h +++ b/libraries/libmdb/mdb.h @@ -99,87 +99,122 @@ MDB_VERFOO(MDB_VERSION_MAJOR,MDB_VERSION_MINOR,MDB_VERSION_PATCH,MDB_VERSION_DATE) /** @} */ -/** Opaque structure for a database environment. A DB environment supports multiple - * databases, all residing in the same shared-memory map. +/** @brief 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. +/** @brief 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. */ +/** @brief A handle for an individual database in the DB environment. */ typedef unsigned int MDB_dbi; -/** Opaque structure for navigating through a database */ +/** @brief 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. */ +/** @brief Generic structure used for passing keys and data in and out of the database. */ typedef struct MDB_val { size_t mv_size; /**< size of the data item */ void *mv_data; /**< address of the data item */ } MDB_val; -/** A callback function used to compare two keys in a database */ +/** @brief A callback function used to compare two keys in a database */ typedef int (MDB_cmp_func)(const MDB_val *a, const MDB_val *b); -/** A callback function used to relocate a position-dependent data item - * in a fixed-address database. The \b newptr gives the item's current address in - * the memory map, and \b oldptr gives its previous address. This callback is - * expected to walk through the fields of the record in newptr and modify any +/** @brief A callback function used to relocate a position-dependent data item + * in a fixed-address database. + * + * The \b newptr gives the item's desired address in + * the memory map, and \b oldptr gives its previous address. The item's actual + * data resides at the address in \b item. This callback is expected to walk + * through the fields of the record in \b item and modify any * values based at the \b oldptr address to be relative to the \b newptr address. + * @param[in,out] item The item that is to be relocated. + * @param[in] oldptr The previous address. + * @param[in] newptr The new address to relocate to. + * @param[in] relctx An application-provided context, set by #mdb_set_relctx(). * @todo This feature is currently unimplemented. */ -typedef void (MDB_rel_func)(void *newptr, void *oldptr, size_t size); +typedef void (MDB_rel_func)(MDB_val *item, void *oldptr, void *newptr, void *relctx); -/** @defgroup mdb_env environment flags +/** @defgroup mdb_env Environment Flags * @{ */ /** mmap at a fixed address */ #define MDB_FIXEDMAP 0x01 + /** no environment directory */ +#define MDB_NOSUBDIR 0x02 /** don't fsync after commit */ #define MDB_NOSYNC 0x10000 /** read only */ #define MDB_RDONLY 0x20000 /** @} */ -/** @defgroup mdb_open database flags +/** @defgroup mdb_open Database Flags * @{ */ /** use reverse string keys */ #define MDB_REVERSEKEY 0x02 /** use sorted duplicates */ #define MDB_DUPSORT 0x04 - /** numeric keys in native byte order */ + /** numeric keys in native byte order. + * The keys must all be of the same size. */ #define MDB_INTEGERKEY 0x08 /** with #MDB_DUPSORT, sorted dup items have fixed size */ #define MDB_DUPFIXED 0x10 /** with #MDB_DUPSORT, dups are numeric in native byte order */ #define MDB_INTEGERDUP 0x20 + /** with #MDB_DUPSORT, use reverse string dups */ +#define MDB_REVERSEDUP 0x40 /** create DB if not already existing */ #define MDB_CREATE 0x40000 /** @} */ -/** @defgroup mdb_put mdb_put flags +/** @defgroup mdb_put Write Flags * @{ */ -/** For mdb_put: don't write if the key already exists. */ +/** For put: Don't write if the key already exists. */ #define MDB_NOOVERWRITE 0x10 -/** For mdb_put: don't write if the key and data pair already exist. - * Only for #MDB_DUPSORT +/** Only for #MDB_DUPSORT
+ * For put: don't write if the key and data pair already exist.
+ * For mdb_cursor_del: remove all duplicate data items. */ #define MDB_NODUPDATA 0x20 +/** For mdb_cursor_put: overwrite the current key/data pair */ +#define MDB_CURRENT 0x40 +/** For put: Just reserve space for data, don't copy it. Return a + * pointer to the reserved space. + */ +#define MDB_RESERVE 0x10000 +/** Data is being appended, don't split full pages. */ +#define MDB_APPEND 0x20000 +/** Store multiple data items in one call. */ +#define MDB_MULTIPLE 0x40000 /* @} */ -/** Cursor operations */ +/** @brief 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_MULTIPLE, /**< Return all the duplicate data items at the current cursor position. 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 */ @@ -191,7 +226,7 @@ typedef enum MDB_cursor_op { 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. - only for #MDB_DUPSORT */ + Only for #MDB_DUPSORT */ MDB_SET, /**< Position at specified key */ MDB_SET_RANGE /**< Position at first key greater than or equal to specified key. */ } MDB_cursor_op; @@ -217,18 +252,19 @@ typedef enum MDB_cursor_op { #define MDB_VERSION_MISMATCH (-30794) /** @} */ -/** Statistics for a database in the environment */ +/** @brief Statistics for a database in the environment */ typedef struct MDB_stat { unsigned int ms_psize; /**< Size of a database page. This is currently the same for all databases. */ unsigned int ms_depth; /**< Depth (height) of the B-tree */ - unsigned long ms_branch_pages; /**< Number of internal (non-leaf) pages */ - unsigned long ms_leaf_pages; /**< Number of leaf pages */ - unsigned long ms_overflow_pages; /**< Number of overflow pages */ - unsigned long ms_entries; /**< Number of data items */ + 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 */ } MDB_stat; - /** Return the mdb library version information. + /** @brief Return the mdb library version information. + * * @param[out] major if non-NULL, the library major version number is copied here * @param[out] minor if non-NULL, the library minor version number is copied here * @param[out] patch if non-NULL, the library patch version number is copied here @@ -236,7 +272,8 @@ typedef struct MDB_stat { */ char *mdb_version(int *major, int *minor, int *patch); - /** Return a string describing a given error code. + /** @brief 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 @@ -247,7 +284,8 @@ char *mdb_version(int *major, int *minor, int *patch); */ char *mdb_strerror(int err); - /** Create an MDB environment handle. + /** @brief Create an MDB environment handle. + * * This function allocates memory for a #MDB_env structure. To release * the allocated memory and discard the handle, call #mdb_env_close(). * Before the handle may be used, it must be opened using #mdb_env_open(). @@ -259,7 +297,8 @@ char *mdb_strerror(int err); */ int mdb_env_create(MDB_env **env); - /** Open an environment handle. + /** @brief Open an environment handle. + * * If this function fails, #mdb_env_close() must be called to discard the #MDB_env handle. * @param[in] env An environment handle returned by #mdb_env_create() * @param[in] path The directory in which the database files reside. This @@ -276,6 +315,12 @@ int mdb_env_create(MDB_env **env); * across multiple invocations. This option may not always work, depending on * how the operating system has allocated memory to shared libraries and other uses. * The feature is highly experimental. + *
  • #MDB_NOSUBDIR + * By default, MDB 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_NOSYNC * Don't perform a synchronous flush after committing a transaction. This means * transactions will exhibit the ACI (atomicity, consistency, and isolation) @@ -303,14 +348,16 @@ int mdb_env_create(MDB_env **env); */ int mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode); - /** Return statistics about the MDB environment. + /** @brief Return statistics about the MDB environment. + * * @param[in] env An environment handle returned by #mdb_env_create() * @param[out] stat The address of an #MDB_stat structure * where the statistics will be copied */ int mdb_env_stat(MDB_env *env, MDB_stat *stat); - /** Flush the data buffers to disk. + /** @brief Flush the data buffers to disk. + * * Data is always written to disk when #mdb_txn_commit() is called, * but the operating system may keep it buffered. MDB always flushes * the OS buffers upon commit as well, unless the environment was @@ -328,7 +375,8 @@ int mdb_env_stat(MDB_env *env, MDB_stat *stat); */ int mdb_env_sync(MDB_env *env, int force); - /** Close the environment and release the memory map. + /** @brief 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. @@ -337,7 +385,8 @@ int mdb_env_sync(MDB_env *env, int force); */ void mdb_env_close(MDB_env *env); - /** Set environment flags. + /** @brief Set environment flags. + * * This may be used to set some flags that weren't already set during * #mdb_env_open(), or to unset these flags. Currently only the * #MDB_NOSYNC flag setting may be changed with this function. @@ -352,7 +401,8 @@ void mdb_env_close(MDB_env *env); */ int mdb_env_set_flags(MDB_env *env, unsigned int flags, int onoff); - /** Get environment flags. + /** @brief Get environment flags. + * * @param[in] env An environment handle returned by #mdb_env_create() * @param[out] flags The address of an integer to store the flags * @return A non-zero error value on failure and 0 on success. Some possible @@ -363,7 +413,8 @@ int mdb_env_set_flags(MDB_env *env, unsigned int flags, int onoff); */ int mdb_env_get_flags(MDB_env *env, unsigned int *flags); - /** Return the path that was used in #mdb_env_open(). + /** @brief Return the path that was used in #mdb_env_open(). + * * @param[in] env An environment handle returned by #mdb_env_create() * @param[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 @@ -376,7 +427,8 @@ int mdb_env_get_flags(MDB_env *env, unsigned int *flags); */ int mdb_env_get_path(MDB_env *env, const char **path); - /** Set the size of the memory map to use for this environment. + /** @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, @@ -392,7 +444,8 @@ int mdb_env_get_path(MDB_env *env, const char **path); */ int mdb_env_set_mapsize(MDB_env *env, size_t size); - /** Set the maximum number of threads for the environment. + /** @brief Set the maximum number of threads 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. * This function may only be called after #mdb_env_create() and before #mdb_env_open(). @@ -404,9 +457,10 @@ int mdb_env_set_mapsize(MDB_env *env, size_t size); *
  • EINVAL - an invalid parameter was specified, or the environment is already open. * */ -int mdb_env_set_maxreaders(MDB_env *env, int readers); +int mdb_env_set_maxreaders(MDB_env *env, unsigned int readers); - /** Get the maximum number of threads for the environment. + /** @brief Get the maximum number of threads for the environment. + * * @param[in] env An environment handle returned by #mdb_env_create() * @param[out] readers Address of an integer to store the number of readers * @return A non-zero error value on failure and 0 on success. Some possible @@ -415,9 +469,10 @@ int mdb_env_set_maxreaders(MDB_env *env, int readers); *
  • EINVAL - an invalid parameter was specified. * */ -int mdb_env_get_maxreaders(MDB_env *env, int *readers); +int mdb_env_get_maxreaders(MDB_env *env, unsigned int *readers); - /** Set the maximum number of databases for the environment. + /** @brief Set the maximum number of databases for the environment. + * * This function is only needed if multiple databases will be used in the * environment. Simpler applications that only use a single database can ignore * this option. @@ -430,15 +485,21 @@ int mdb_env_get_maxreaders(MDB_env *env, int *readers); *
  • EINVAL - an invalid parameter was specified, or the environment is already open. * */ -int mdb_env_set_maxdbs(MDB_env *env, int dbs); +int mdb_env_set_maxdbs(MDB_env *env, MDB_dbi dbs); - /** Create a transaction for use with the environment. + /** @brief Create a transaction for use with the environment. + * * The transaction handle may be discarded using #mdb_txn_abort() or #mdb_txn_commit(). * @note Transactions may not span threads, a transaction must only be used by a * single thread. * @note Cursors may not span transactions; each cursor must be opened and closed * within a single transaction. * @param[in] env An environment handle returned by #mdb_env_create() + * @param[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 may not issue any other operations besides mdb_txn_begin, + * mdb_txn_abort, or mdb_txn_commit while it has active child transactions. * @param[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. @@ -456,12 +517,12 @@ int mdb_env_set_maxdbs(MDB_env *env, int dbs); * the reader lock table is full. See #mdb_env_set_maxreaders(). * */ -int mdb_txn_begin(MDB_env *env, unsigned int flags, MDB_txn **txn); +int mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **txn); - /** Commit all the operations of a transaction into the database. - * All cursors opened within the transaction must be closed before the transaction - * is committed. - * The transaction handle will be freed and must not be used again after this call. + /** @brief Commit all the operations of a transaction into the database. + * + * All cursors opened within the transaction will be closed by this call. The cursors + * and transaction handle will be freed and must not be used again after this call. * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @return A non-zero error value on failure and 0 on success. Some possible * errors are: @@ -473,18 +534,19 @@ int mdb_txn_begin(MDB_env *env, unsigned int flags, MDB_txn **txn); */ int mdb_txn_commit(MDB_txn *txn); - /** Abandon all the operations of the transaction instead of saving them. - * All cursors opened within the transaction must be closed before the transaction - * is aborted. - * The transaction handle will be freed and must not be used again after this call. + /** @brief Abandon all the operations of the transaction instead of saving them. + * + * All cursors opened within the transaction will be closed by this call. The cursors + * and transaction handle will be freed and must not be used again after this call. * @param[in] txn A transaction handle returned by #mdb_txn_begin() */ void mdb_txn_abort(MDB_txn *txn); - /** Reset a read-only transaction. + /** @brief Reset a read-only transaction. + * * This releases the current reader lock but doesn't free the * transaction handle, allowing it to be used again later by #mdb_txn_renew(). - * It otherwise has the same affect as #mdb_txn_abort() but saves some memory + * It otherwise has the same effect as #mdb_txn_abort() but saves some memory * allocation/deallocation overhead if a thread is going to start a new * read-only transaction again soon. * All cursors opened within the transaction must be closed before the transaction @@ -497,7 +559,8 @@ void mdb_txn_abort(MDB_txn *txn); */ void mdb_txn_reset(MDB_txn *txn); - /** Renew a read-only transaction. + /** @brief Renew a read-only transaction. + * * This acquires a new reader lock for a transaction handle that had been * released by #mdb_txn_reset(). It must be called before a reset transaction * may be used again. @@ -512,8 +575,11 @@ void mdb_txn_reset(MDB_txn *txn); */ int mdb_txn_renew(MDB_txn *txn); - /** Open a database in the environment. - * The database handle may be discarded by calling #mdb_close(). + /** @brief Open a database in the environment. + * + * The database handle may be discarded by calling #mdb_close(). Only + * one thread should call this function; it is not mutex-protected in + * a read-only transaction. * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] name The name of the database to open. If only a single * database is needed in the enviroment, this value may be NULL. @@ -530,11 +596,9 @@ int mdb_txn_renew(MDB_txn *txn); * 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. On Big-Endian systems - * this flag has no effect. On Little-Endian systems this flag behaves - * the same as #MDB_REVERSEKEY. This flag is simply provided as a - * convenience so that applications don't need to detect Endianness themselves - * when using integers as keys. + * Keys are binary integers in native byte order. Setting this option + * requires all keys to be the same size, typically sizeof(int) + * or sizeof(size_t). *
  • #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 @@ -544,6 +608,9 @@ int mdb_txn_renew(MDB_txn *txn); *
  • #MDB_INTEGERDUP * This option specifies that duplicate data items are also integers, and * should be sorted as such. + *
  • #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. @@ -559,7 +626,8 @@ int mdb_txn_renew(MDB_txn *txn); */ int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi); - /** Retrieve statistics for a database. + /** @brief Retrieve statistics for a database. + * * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] dbi A database handle returned by #mdb_open() * @param[out] stat The address of an #MDB_stat structure @@ -572,21 +640,38 @@ int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi); */ int mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *stat); - /** Close a database handle. + /** @brief Close a database handle. + * + * 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 any further. + * @param[in] env An environment handle returned by #mdb_env_create() + * @param[in] dbi A database handle returned by #mdb_open() + */ +void mdb_close(MDB_env *env, MDB_dbi dbi); + + /** @brief Delete a database and/or free all its pages. + * + * If the \b del parameter is non-zero the DB handle will be closed + * and the DB will be deleted. * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] dbi A database handle returned by #mdb_open() + * @param[in] del non-zero to delete the DB from the environment, + * otherwise just free its pages. + * @return A non-zero error value on failure and 0 on success. */ -void mdb_close(MDB_txn *txn, MDB_dbi dbi); +int mdb_drop(MDB_txn *txn, MDB_dbi dbi, int del); - /** Set a custom key comparison function for a database. + /** @brief 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 + * If no comparison function is specified, and no speAGAINcial key flags were specified * with #mdb_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 function must be used by every - * process accessing the database, every time the database is 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. * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] dbi A database handle returned by #mdb_open() * @param[in] cmp A #MDB_cmp_func function @@ -598,7 +683,8 @@ void mdb_close(MDB_txn *txn, MDB_dbi dbi); */ int mdb_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp); - /** Set a custom data comparison function for a #MDB_DUPSORT database. + /** @brief 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 @@ -607,8 +693,8 @@ int mdb_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp); * with #mdb_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 function must be used by every - * process accessing the database, every time the database is 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. * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] dbi A database handle returned by #mdb_open() * @param[in] cmp A #MDB_cmp_func function @@ -620,7 +706,8 @@ int mdb_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp); */ int mdb_set_dupsort(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp); - /** Set a relocation function for a #MDB_FIXEDMAP database. + /** @brief Set a relocation function for a #MDB_FIXEDMAP database. + * * @todo The relocation function is called whenever it is necessary to move the data * of an item to a different position in the database (e.g. through tree * balancing operations, shifts as a result of adds or deletes, etc.). It is @@ -639,13 +726,35 @@ int mdb_set_dupsort(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp); */ int mdb_set_relfunc(MDB_txn *txn, MDB_dbi dbi, MDB_rel_func *rel); - /** Get items from a database. + /** @brief Set a context pointer for a #MDB_FIXEDMAP database's relocation function. + * + * See #mdb_set_relfunc and #MDB_rel_func for more details. + * @param[in] txn A transaction handle returned by #mdb_txn_begin() + * @param[in] dbi A database handle returned by #mdb_open() + * @param[in] ctx An arbitrary pointer for whatever the application needs. + * It will be passed to the callback function set by #mdb_set_relfunc + * as its \b relctx parameter whenever the callback is invoked. + * @return A non-zero error value on failure and 0 on success. Some possible + * errors are: + * + */ +int mdb_set_relctx(MDB_txn *txn, MDB_dbi dbi, void *ctx); + + /** @brief 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 #mdb_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. * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] dbi A database handle returned by #mdb_open() * @param[in] key The key to search for in the database @@ -659,7 +768,8 @@ int mdb_set_relfunc(MDB_txn *txn, MDB_dbi dbi, MDB_rel_func *rel); */ int mdb_get(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data); - /** Store items into a database. + /** @brief 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 @@ -667,7 +777,7 @@ int mdb_get(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data); * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] dbi A database handle returned by #mdb_open() * @param[in] key The key to store in the database - * @param[in] data The data to store + * @param[in,out] data The data to store * @param[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. @@ -680,7 +790,8 @@ int mdb_get(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data); *
  • #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 database supports duplicates (#MDB_DUPSORT). The \b data + * parameter will be set to point to the existing item. * * @return A non-zero error value on failure and 0 on success. Some possible * errors are: @@ -693,7 +804,8 @@ int mdb_get(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data); int mdb_put(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data, unsigned int flags); - /** Delete items from a database. + /** @brief Delete items from a database. + * * This function removes key/data pairs from the database. * If the database does not support sorted duplicate data items * (#MDB_DUPSORT) the data parameter is ignored. @@ -716,11 +828,10 @@ int mdb_put(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data, */ int mdb_del(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data); - /** Create a cursor handle. + /** @brief Create a cursor handle. + * * Cursors are associated with a specific transaction and database and * may not span threads. - * @todo Cursors only support read operations. Support for cursor_put() and - * cursor_del() needs to be added. * @param[in] txn A transaction handle returned by #mdb_txn_begin() * @param[in] dbi A database handle returned by #mdb_open() * @param[out] cursor Address where the new #MDB_cursor handle will be stored @@ -732,21 +843,32 @@ int mdb_del(MDB_txn *txn, MDB_dbi dbi, MDB_val *key, MDB_val *data); */ int mdb_cursor_open(MDB_txn *txn, MDB_dbi dbi, MDB_cursor **cursor); - /** Close a cursor handle. + /** @brief Close a cursor handle. + * * The cursor handle will be freed and must not be used again after this call. * @param[in] cursor A cursor handle returned by #mdb_cursor_open() */ void mdb_cursor_close(MDB_cursor *cursor); - /** Retrieve by cursor. + /** @brief Return the cursor's transaction handle. + * + * @param[in] cursor A cursor handle returned by #mdb_cursor_open() + */ +MDB_txn *mdb_cursor_txn(MDB_cursor *cursor); + + /** @brief Return the cursor's database handle. + * + * @param[in] cursor A cursor handle returned by #mdb_cursor_open() + */ +MDB_dbi mdb_cursor_dbi(MDB_cursor *cursor); + + /** @brief 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. - * @bug Cursors are not coordinated with write operations. If a cursor in a - * write transaction is performing a sequential scan while records are being - * inserted or deleted in the same transaction, the cursor will be corrupted. * @param[in] cursor A cursor handle returned by #mdb_cursor_open() * @param[in,out] key The key for a retrieved item * @param[in,out] data The data of a retrieved item @@ -761,7 +883,62 @@ void mdb_cursor_close(MDB_cursor *cursor); int mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data, MDB_cursor_op op); - /** Return count of duplicates for current key. + /** @brief Store by cursor. + * + * This function stores key/data pairs into the database. + * If the function fails for any reason, the state of the cursor will be + * unchanged. If the function succeeds and an item is inserted into the + * database, the cursor is always positioned to refer to the newly inserted item. + * @param[in] cursor A cursor handle returned by #mdb_cursor_open() + * @param[in] key The key operated on. + * @param[in] data The data operated on. + * @param[in] flags Options for this operation. This parameter + * must be set to 0 or one of the values described here. + * + * @return A non-zero error value on failure and 0 on success. Some possible + * errors are: + * + */ +int mdb_cursor_put(MDB_cursor *cursor, MDB_val *key, MDB_val *data, + unsigned int flags); + + /** @brief Delete current key/data pair + * + * This function deletes the key/data pair to which the cursor refers. + * @param[in] cursor A cursor handle returned by #mdb_cursor_open() + * @param[in] flags Options for this operation. This parameter + * must be set to 0 or one of the values described here. + * + * @return A non-zero error value on failure and 0 on success. Some possible + * errors are: + * + */ +int mdb_cursor_del(MDB_cursor *cursor, unsigned int flags); + + /** @brief Return count of duplicates for current key. + * * This call is only valid on databases that support sorted duplicate * data items #MDB_DUPSORT. * @param[in] cursor A cursor handle returned by #mdb_cursor_open() @@ -772,9 +949,10 @@ int mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data, *
  • EINVAL - cursor is not initialized, or an invalid parameter was specified. * */ -int mdb_cursor_count(MDB_cursor *cursor, unsigned long *countp); +int mdb_cursor_count(MDB_cursor *cursor, size_t *countp); - /** Compare two data items according to a particular database. + /** @brief 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. * @param[in] txn A transaction handle returned by #mdb_txn_begin() @@ -785,5 +963,16 @@ int mdb_cursor_count(MDB_cursor *cursor, unsigned long *countp); */ int mdb_cmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b); + /** @brief Compare two data items according to a particular database. + * + * This returns a comparison as if the two items were data items of + * a sorted duplicates #MDB_DUPSORT database. + * @param[in] txn A transaction handle returned by #mdb_txn_begin() + * @param[in] dbi A database handle returned by #mdb_open() + * @param[in] a The first item to compare + * @param[in] b The second item to compare + * @return < 0 if a < b, 0 if a == b, > 0 if a > b + */ +int mdb_dcmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b); /** @} */ #endif /* _MDB_H_ */