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
+ * 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
* @{
#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
#define MDB_CURRENT 0x40
/* @} */
-/** Cursor operations */
+/** 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.
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;
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.
* <li>EINVAL - an invalid parameter was specified, or the environment is already open.
* </ul>
*/
-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.
* @param[in] env An environment handle returned by #mdb_env_create()
* <li>EINVAL - an invalid parameter was specified.
* </ul>
*/
-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.
* This function is only needed if multiple databases will be used in the
* <li>EINVAL - an invalid parameter was specified, or the environment is already open.
* </ul>
*/
-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.
* The transaction handle may be discarded using #mdb_txn_abort() or #mdb_txn_commit().
/** 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
int mdb_txn_renew(MDB_txn *txn);
/** Open a database in the environment.
- * The database handle may be discarded by calling #mdb_close().
+ * 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.
* keys may have multiple data items, stored in sorted order.) By default
* keys must be unique and may have only a single data item.
* <li>#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).
* <li>#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
* <li>#MDB_INTEGERDUP
* This option specifies that duplicate data items are also integers, and
* should be sorted as such.
+ * <li>#MDB_REVERSEDUP
+ * This option specifies that duplicate data items should be compared as
+ * strings in reverse order.
* <li>#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.
int mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *stat);
/** 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);
+
+ /** 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.
* 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
* 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
*/
int mdb_set_relfunc(MDB_txn *txn, MDB_dbi dbi, MDB_rel_func *rel);
+ /** 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:
+ * <ul>
+ * <li>EINVAL - an invalid parameter was specified.
+ * </ul>
+ */
+int mdb_set_relctx(MDB_txn *txn, MDB_dbi dbi, void *ctx);
+
/** 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
* 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
* @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.
* <li>#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.
* </ul>
* @return A non-zero error value on failure and 0 on success. Some possible
* errors are:
* <li>EINVAL - cursor is not initialized, or an invalid parameter was specified.
* </ul>
*/
-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.
* This returns a comparison as if the two data items were keys in the
*/
int mdb_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
+ * 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_ */
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