tdb: Added doxygen documentation.

Autobuild-User: Andreas Schneider <asn@samba.org>
Autobuild-Date: Wed Jan 19 11:26:34 CET 2011 on sn-devel-104

1 files changed, 693 insertions, 25 deletions

diff --git a/lib/tdb/include/tdb.h b/lib/tdb/include/tdb.h
index 0ee5e1b5bd..658e81ea1f 100644
--- a/lib/tdb/include/tdb.h
+++ b/lib/tdb/include/tdb.h
@@ -32,36 +32,66 @@ extern "C" {
 
 #include "signal.h"
 
-/* flags to tdb_store() */
-#define TDB_REPLACE 1		/* Unused */
-#define TDB_INSERT 2 		/* Don't overwrite an existing entry */
-#define TDB_MODIFY 3		/* Don't create an existing entry    */
-
-/* flags for tdb_open() */
-#define TDB_DEFAULT 0 /* just a readability place holder */
-#define TDB_CLEAR_IF_FIRST 1
-#define TDB_INTERNAL 2 /* don't store on disk */
-#define TDB_NOLOCK   4 /* don't do any locking */
-#define TDB_NOMMAP   8 /* don't use mmap */
-#define TDB_CONVERT 16 /* convert endian (internal use) */
-#define TDB_BIGENDIAN 32 /* header is big-endian (internal use) */
-#define TDB_NOSYNC   64 /* don't use synchronous transactions */
-#define TDB_SEQNUM   128 /* maintain a sequence number */
-#define TDB_VOLATILE   256 /* Activate the per-hashchain freelist, default 5 */
-#define TDB_ALLOW_NESTING 512 /* Allow transactions to nest */
-#define TDB_DISALLOW_NESTING 1024 /* Disallow transactions to nest */
-#define TDB_INCOMPATIBLE_HASH 2048 /* Better hashing: can't be opened by tdb < 1.2.6. */
-
-/* error codes */
+/**
+ * @defgroup tdb The tdb API
+ *
+ * tdb is a Trivial database. In concept, it is very much like GDBM, and BSD's
+ * DB except that it allows multiple simultaneous writers and uses locking
+ * internally to keep writers from trampling on each other. tdb is also
+ * extremely small.
+ *
+ * @section tdb_interface Interface
+ *
+ * The interface is very similar to gdbm except for the following:
+ *
+ * <ul>
+ * <li>different open interface. The tdb_open call is more similar to a
+ * traditional open()</li>
+ * <li>no tdbm_reorganise() function</li>
+ * <li>no tdbm_sync() function. No operations are cached in the library
+ *     anyway</li>
+ * <li>added a tdb_traverse() function for traversing the whole database</li>
+ * <li>added transactions support</li>
+ * </ul>
+ *
+ * A general rule for using tdb is that the caller frees any returned TDB_DATA
+ * structures. Just call free(p.dptr) to free a TDB_DATA return value called p.
+ * This is the same as gdbm.
+ *
+ * @{
+ */
+
+/** Flags to tdb_store() */
+#define TDB_REPLACE 1		/** Unused */
+#define TDB_INSERT 2 		/** Don't overwrite an existing entry */
+#define TDB_MODIFY 3		/** Don't create an existing entry    */
+
+/** Flags for tdb_open() */
+#define TDB_DEFAULT 0 /** just a readability place holder */
+#define TDB_CLEAR_IF_FIRST 1 /** If this is the first open, wipe the db */
+#define TDB_INTERNAL 2 /** Don't store on disk */
+#define TDB_NOLOCK   4 /** Don't do any locking */
+#define TDB_NOMMAP   8 /** Don't use mmap */
+#define TDB_CONVERT 16 /** Convert endian (internal use) */
+#define TDB_BIGENDIAN 32 /** Header is big-endian (internal use) */
+#define TDB_NOSYNC   64 /** Don't use synchronous transactions */
+#define TDB_SEQNUM   128 /** Maintain a sequence number */
+#define TDB_VOLATILE   256 /** Activate the per-hashchain freelist, default 5 */
+#define TDB_ALLOW_NESTING 512 /** Allow transactions to nest */
+#define TDB_DISALLOW_NESTING 1024 /** Disallow transactions to nest */
+#define TDB_INCOMPATIBLE_HASH 2048 /** Better hashing: can't be opened by tdb < 1.2.6. */
+
+/** The tdb error codes */
 enum TDB_ERROR {TDB_SUCCESS=0, TDB_ERR_CORRUPT, TDB_ERR_IO, TDB_ERR_LOCK, 
 		TDB_ERR_OOM, TDB_ERR_EXISTS, TDB_ERR_NOLOCK, TDB_ERR_LOCK_TIMEOUT,
 		TDB_ERR_NOEXIST, TDB_ERR_EINVAL, TDB_ERR_RDONLY,
 		TDB_ERR_NESTING};
 
-/* debugging uses one of the following levels */
+/** Debugging uses one of the following levels */
 enum tdb_debug_level {TDB_DEBUG_FATAL = 0, TDB_DEBUG_ERROR, 
 		      TDB_DEBUG_WARNING, TDB_DEBUG_TRACE};
 
+/** The tdb data structure */
 typedef struct TDB_DATA {
 	unsigned char *dptr;
 	size_t dsize;
@@ -79,7 +109,7 @@ typedef struct TDB_DATA {
 #endif
 #endif
 
-/* this is the context structure that is returned from a db open */
+/** This is the context structure that is returned from a db open. */
 typedef struct tdb_context TDB_CONTEXT;
 
 typedef int (*tdb_traverse_func)(struct tdb_context *, TDB_DATA, TDB_DATA, void *);
@@ -91,63 +121,701 @@ struct tdb_logging_context {
         void *log_private;
 };
 
+/**
+ * @brief Open the database and creating it if necessary.
+ *
+ * @param[in]  name     The name of the db to open.
+ *
+ * @param[in]  hash_size The hash size is advisory, use zero for a default
+ *                       value.
+ *
+ * @param[in]  tdb_flags The flags to use to open the db:\n\n
+ *                         TDB_CLEAR_IF_FIRST - Clear database if we are the
+ *                                              only one with it open\n
+ *                         TDB_INTERNAL - Don't use a file, instaed store the
+ *                                        data in memory. The filename is
+ *                                        ignored in this case.\n
+ *                         TDB_NOLOCK - Don't do any locking\n
+ *                         TDB_NOMMAP - Don't use mmap\n
+ *                         TDB_NOSYNC - Don't synchronise transactions to disk\n
+ *                         TDB_SEQNUM - Maintain a sequence number\n
+ *                         TDB_VOLATILE - activate the per-hashchain freelist,
+ *                                        default 5.\n
+ *                         TDB_ALLOW_NESTING - Allow transactions to nest.\n
+ *                         TDB_DISALLOW_NESTING - Disallow transactions to nest.\n
+ *
+ * @param[in]  open_flags Flags for the open(2) function.
+ *
+ * @param[in]  mode     The mode for the open(2) function.
+ *
+ * @return              A tdb context structure, NULL on error.
+ */
 struct tdb_context *tdb_open(const char *name, int hash_size, int tdb_flags,
 		      int open_flags, mode_t mode);
+
+/**
+ * @brief Open the database and creating it if necessary.
+ *
+ * This is like tdb_open(), but allows you to pass an initial logging and
+ * hash function. Be careful when passing a hash function - all users of the
+ * database must use the same hash function or you will get data corruption.
+ *
+ * @param[in]  name     The name of the db to open.
+ *
+ * @param[in]  hash_size The hash size is advisory, use zero for a default
+ *                       value.
+ *
+ * @param[in]  tdb_flags The flags to use to open the db:\n\n
+ *                         TDB_CLEAR_IF_FIRST - Clear database if we are the
+ *                                              only one with it open\n
+ *                         TDB_INTERNAL - Don't use a file, instaed store the
+ *                                        data in memory. The filename is
+ *                                        ignored in this case.\n
+ *                         TDB_NOLOCK - Don't do any locking\n
+ *                         TDB_NOMMAP - Don't use mmap\n
+ *                         TDB_NOSYNC - Don't synchronise transactions to disk\n
+ *                         TDB_SEQNUM - Maintain a sequence number\n
+ *                         TDB_VOLATILE - activate the per-hashchain freelist,
+ *                                        default 5.\n
+ *                         TDB_ALLOW_NESTING - Allow transactions to nest.\n
+ *                         TDB_DISALLOW_NESTING - Disallow transactions to nest.\n
+ *
+ * @param[in]  open_flags Flags for the open(2) function.
+ *
+ * @param[in]  mode     The mode for the open(2) function.
+ *
+ * @param[in]  log_ctx  The logging function to use.
+ *
+ * @param[in]  hash_fn  The hash function you want to use.
+ *
+ * @return              A tdb context structure, NULL on error.
+ *
+ * @see tdb_open()
+ */
 struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 			 int open_flags, mode_t mode,
 			 const struct tdb_logging_context *log_ctx,
 			 tdb_hash_func hash_fn);
+
+/**
+ * @brief Set the maximum number of dead records per hash chain.
+ *
+ * @param[in]  tdb      The database handle to set the maximum.
+ *
+ * @param[in]  max_dead The maximum number of dead records per hash chain.
+ */
 void tdb_set_max_dead(struct tdb_context *tdb, int max_dead);
 
+/**
+ * @brief Reopen a tdb.
+ *
+ * This can be used after a fork to ensure that we have an independent seek
+ * pointer from our parent and to re-establish locks.
+ *
+ * @param[in]  tdb      The database to reopen.
+ *
+ * @return              0 on success, -1 on error.
+ */
 int tdb_reopen(struct tdb_context *tdb);
+
+/**
+ * @brief Reopen all tdb's
+ *
+ * If the parent is longlived (ie. a parent daemon architecture), we know it
+ * will keep it's active lock on a tdb opened with CLEAR_IF_FIRST. Thus for
+ * child processes we don't have to add an active lock. This is essential to
+ * improve performance on systems that keep POSIX locks as a non-scalable data
+ * structure in the kernel.
+ *
+ * @param[in]  parent_longlived Wether the parent is longlived or not.
+ *
+ * @return              0 on success, -1 on error.
+ */
 int tdb_reopen_all(int parent_longlived);
+
+/**
+ * @brief Set a different tdb logging function.
+ *
+ * @param[in]  tdb      The tdb to set the logging function.
+ *
+ * @param[in]  log_ctx  The logging function to set.
+ */
 void tdb_set_logging_function(struct tdb_context *tdb, const struct tdb_logging_context *log_ctx);
+
+/**
+ * @brief Get the tdb last error code.
+ *
+ * @param[in]  tdb      The tdb to get the error code from.
+ *
+ * @return              A TDB_ERROR code.
+ *
+ * @see TDB_ERROR
+ */
 enum TDB_ERROR tdb_error(struct tdb_context *tdb);
+
+/**
+ * @brief Get a error string for the last tdb error
+ *
+ * @param[in]  tdb      The tdb to get the error code from.
+ *
+ * @return              An error string.
+ */
 const char *tdb_errorstr(struct tdb_context *tdb);
+
+/**
+ * @brief Fetch an entry in the database given a key.
+ *
+ * The caller must free the resulting data.
+ *
+ * @param[in]  tdb      The tdb to fetch the key.
+ *
+ * @param[in]  key      The key to fetch.
+ *
+ * @return              The key entry found in the database, NULL on error with
+ *                      TDB_ERROR set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 TDB_DATA tdb_fetch(struct tdb_context *tdb, TDB_DATA key);
+
+/**
+ * @brief Hand a record to a parser function without allocating it.
+ *
+ * This function is meant as a fast tdb_fetch alternative for large records
+ * that are frequently read. The "key" and "data" arguments point directly
+ * into the tdb shared memory, they are not aligned at any boundary.
+ *
+ * @warning The parser is called while tdb holds a lock on the record. DO NOT
+ * call other tdb routines from within the parser. Also, for good performance
+ * you should make the parser fast to allow parallel operations.
+ *
+ * @param[in]  tdb      The tdb to parse the record.
+ *
+ * @param[in]  key      The key to parse.
+ *
+ * @param[in]  parser   The parser to use to parse the data.
+ *
+ * @param[in]  private_data A private data pointer which is passed to the parser
+ *                          function.
+ *
+ * @return              -1 if the record was not found. If the record was found,
+ *                      the return value of "parser" is passed up to the caller.
+ */
 int tdb_parse_record(struct tdb_context *tdb, TDB_DATA key,
 			      int (*parser)(TDB_DATA key, TDB_DATA data,
 					    void *private_data),
 			      void *private_data);
+
+/**
+ * @brief Delete an entry in the database given a key.
+ *
+ * @param[in]  tdb      The tdb to delete the key.
+ *
+ * @param[in]  key      The key to delete.
+ *
+ * @return              0 on success, -1 if the key doesn't exist.
+ */
 int tdb_delete(struct tdb_context *tdb, TDB_DATA key);
+
+/**
+ * @brief Store an element in the database.
+ *
+ * This replaces any existing element with the same key.
+ *
+ * @param[in]  tdb      The tdb to store the entry.
+ *
+ * @param[in]  key      The key to use to store the entry.
+ *
+ * @param[in]  dbuf     The data to store under the key.
+ *
+ * @param[in]  flag     The flags to store the key:\n\n
+ *                      TDB_INSERT: Don't overwrite an existing entry.\n
+ *                      TDB_MODIFY: Don't create a new entry\n
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_store(struct tdb_context *tdb, TDB_DATA key, TDB_DATA dbuf, int flag);
+
+/**
+ * @brief Append data to an entry.
+ *
+ * If the entry doesn't exist, it will create a new one.
+ *
+ * @param[in]  tdb      The database to use.
+ *
+ * @param[in]  key      The key to append the data.
+ *
+ * @param[in]  new_dbuf The data to append to the key.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_append(struct tdb_context *tdb, TDB_DATA key, TDB_DATA new_dbuf);
+
+/**
+ * @brief Close a database.
+ *
+ * @param[in]  tdb      The database to close.
+ *
+ * @return              0 for success, -1 on error.
+ */
 int tdb_close(struct tdb_context *tdb);
+
+/**
+ * @brief Find the first entry in the database and return its key.
+ *
+ * The caller must free the returned data.
+ *
+ * @param[in]  tdb      The database to use.
+ *
+ * @return              The first entry of the database, an empty TDB_DATA entry
+ *                      if the database is empty.
+ */
 TDB_DATA tdb_firstkey(struct tdb_context *tdb);
+
+/**
+ * @brief Find the next entry in the database, returning its key.
+ *
+ * The caller must free the returned data.
+ *
+ * @param[in]  tdb      The database to use.
+ *
+ * @param[in]  key      The key from which you want the next key.
+ *
+ * @return              The next entry of the current key, an empty TDB_DATA
+ *                      entry if there is no entry.
+ */
 TDB_DATA tdb_nextkey(struct tdb_context *tdb, TDB_DATA key);
-int tdb_traverse(struct tdb_context *tdb, tdb_traverse_func fn, void *);
-int tdb_traverse_read(struct tdb_context *tdb, tdb_traverse_func fn, void *);
+
+/**
+ * @brief Traverse the entire database.
+ *
+ * While travering the function fn(tdb, key, data, state) is called on each
+ * element. If fn is NULL then it is not called. A non-zero return value from
+ * fn() indicates that the traversal should stop. Traversal callbacks may not
+ * start transactions.
+ *
+ * @warning The data buffer given to the callback fn does NOT meet the alignment
+ * restrictions malloc gives you.
+ *
+ * @param[in]  tdb      The database to traverse.
+ *
+ * @param[in]  fn       The function to call on each entry.
+ *
+ * @param[in]  private_data The private data which should be passed to the
+ *                          traversing function.
+ *
+ * @return              The record count traversed, -1 on error.
+ */
+int tdb_traverse(struct tdb_context *tdb, tdb_traverse_func fn, void *private_data);
+
+/**
+ * @brief Traverse the entire database.
+ *
+ * While traversing the database the function fn(tdb, key, data, state) is
+ * called on each element, but marking the database read only during the
+ * traversal, so any write operations will fail. This allows tdb to use read
+ * locks, which increases the parallelism possible during the traversal.
+ *
+ * @param[in]  tdb      The database to traverse.
+ *
+ * @param[in]  fn       The function to call on each entry.
+ *
+ * @param[in]  private_data The private data which should be passed to the
+ *                          traversing function.
+ *
+ * @return              The record count traversed, -1 on error.
+ */
+int tdb_traverse_read(struct tdb_context *tdb, tdb_traverse_func fn, void *private_data);
+
+/**
+ * @brief Check if an entry in the database exists.
+ *
+ * @note 1 is returned if the key is found and 0 is returned if not found this
+ * doesn't match the conventions in the rest of this module, but is compatible
+ * with gdbm.
+ *
+ * @param[in]  tdb      The database to check if the entry exists.
+ *
+ * @param[in]  key      The key to check if the entry exists.
+ *
+ * @return              1 if the key is found, 0 if not.
+ */
 int tdb_exists(struct tdb_context *tdb, TDB_DATA key);
+
+/**
+ * @brief Lock entire database with a write lock.
+ *
+ * @param[in]  tdb      The database to lock.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_lockall(struct tdb_context *tdb);
+
+/**
+ * @brief Lock entire database with a write lock.
+ *
+ * This is the non-blocking call.
+ *
+ * @param[in]  tdb      The database to lock.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_lockall()
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_lockall_nonblock(struct tdb_context *tdb);
+
+/**
+ * @brief Unlock entire database with write lock.
+ *
+ * @param[in]  tdb      The database to unlock.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_lockall()
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_unlockall(struct tdb_context *tdb);
+
+/**
+ * @brief Lock entire database with a read lock.
+ *
+ * @param[in]  tdb      The database to lock.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_lockall_read(struct tdb_context *tdb);
+
+/**
+ * @brief Lock entire database with a read lock.
+ *
+ * This is the non-blocking call.
+ *
+ * @param[in]  tdb      The database to lock.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_lockall_read()
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_lockall_read_nonblock(struct tdb_context *tdb);
+
+/**
+ * @brief Unlock entire database with read lock.
+ *
+ * @param[in]  tdb      The database to unlock.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_lockall_read()
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_unlockall_read(struct tdb_context *tdb);
+
+/**
+ * @brief Lock entire database with write lock - mark only.
+ *
+ * @todo Add more details.
+ *
+ * @param[in]  tdb      The database to mark.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_lockall_mark(struct tdb_context *tdb);
+
+/**
+ * @brief Lock entire database with write lock - unmark only.
+ *
+ * @todo Add more details.
+ *
+ * @param[in]  tdb      The database to mark.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_lockall_unmark(struct tdb_context *tdb);
+
+/**
+ * @brief Get the name of the current tdb file.
+ *
+ * This is useful for external logging functions.
+ *
+ * @param[in]  tdb      The database to get the name from.
+ *
+ * @return              The name of the database.
+ */
 const char *tdb_name(struct tdb_context *tdb);
+
+/**
+ * @brief Get the underlying file descriptor being used by tdb.
+ *
+ * This is useful for external routines that want to check the device/inode
+ * of the fd.
+ *
+ * @param[in]  tdb      The database to get the fd from.
+ *
+ * @return              The file descriptor or -1.
+ */
 int tdb_fd(struct tdb_context *tdb);
+
+/**
+ * @brief Get the current logging function.
+ *
+ * This is useful for external tdb routines that wish to log tdb errors.
+ *
+ * @param[in]  tdb      The database to get the logging function from.
+ *
+ * @return              The logging function of the database.
+ *
+ * @see tdb_get_logging_private()
+ */
 tdb_log_func tdb_log_fn(struct tdb_context *tdb);
+
+/**
+ * @brief Get the private data of the logging function.
+ *
+ * @param[in]  tdb      The database to get the data from.
+ *
+ * @return              The private data pointer of the logging function.
+ *
+ * @see tdb_log_fn()
+ */
 void *tdb_get_logging_private(struct tdb_context *tdb);
+
+/**
+ * @brief Start a transaction.
+ *
+ * All operations after the transaction start can either be committed with
+ * tdb_transaction_commit() or cancelled with tdb_transaction_cancel().
+ *
+ * If you call tdb_transaction_start() again on the same tdb context while a
+ * transaction is in progress, then the same transaction buffer is re-used. The
+ * number of tdb_transaction_{commit,cancel} operations must match the number
+ * of successful tdb_transaction_start() calls.
+ *
+ * Note that transactions are by default disk synchronous, and use a recover
+ * area in the database to automatically recover the database on the next open
+ * if the system crashes during a transaction. You can disable the synchronous
+ * transaction recovery setup using the TDB_NOSYNC flag, which will greatly
+ * speed up operations at the risk of corrupting your database if the system
+ * crashes.
+ *
+ * Operations made within a transaction are not visible to other users of the
+ * database until a successful commit.
+ *
+ * @param[in]  tdb      The database to start the transaction.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_transaction_start(struct tdb_context *tdb);
+
+/**
+ * @brief Start a transaction, non-blocking.
+ *
+ * @param[in]  tdb      The database to start the transaction.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ * @see tdb_transaction_start()
+ */
 int tdb_transaction_start_nonblock(struct tdb_context *tdb);
+
+/**
+ * @brief Prepare to commit a current transaction, for two-phase commits.
+ *
+ * Once prepared for commit, the only allowed calls are tdb_transaction_commit()
+ * or tdb_transaction_cancel(). Preparing allocates disk space for the pending
+ * updates, so a subsequent commit should succeed (barring any hardware
+ * failures).
+ *
+ * @param[in]  tdb      The database to prepare the commit.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_transaction_prepare_commit(struct tdb_context *tdb);
+
+/**
+ * @brief Commit a current transaction.
+ *
+ * This updates the database and releases the current transaction locks.
+ *
+ * @param[in]  tdb      The database to commit the transaction.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_transaction_commit(struct tdb_context *tdb);
+
+/**
+ * @brief Cancel a current transaction.
+ *
+ * This discards all write and lock operations that have been made since the
+ * transaction started.
+ *
+ * @param[in]  tdb      The tdb to cancel the transaction on.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_transaction_cancel(struct tdb_context *tdb);
+
+/**
+ * @brief Get the tdb sequence number.
+ *
+ * Only makes sense if the writers opened with TDB_SEQNUM set. Note that this
+ * sequence number will wrap quite quickly, so it should only be used for a
+ * 'has something changed' test, not for code that relies on the count of the
+ * number of changes made. If you want a counter then use a tdb record.
+ *
+ * The aim of this sequence number is to allow for a very lightweight test of a
+ * possible tdb change.
+ *
+ * @param[in]  tdb      The database to get the sequence number from.
+ *
+ * @return              The sequence number or 0.
+ *
+ * @see tdb_open()
+ * @see tdb_enable_seqnum()
+ */
 int tdb_get_seqnum(struct tdb_context *tdb);
+
+/**
+ * @brief Get the hash size.
+ *
+ * @param[in]  tdb      The database to get the hash size from.
+ *
+ * @return              The hash size.
+ */
 int tdb_hash_size(struct tdb_context *tdb);
+
+/**
+ * @brief Get the map size.
+ *
+ * @param[in]  tdb     The database to get the map size from.
+ *
+ * @return             The map size.
+ */
 size_t tdb_map_size(struct tdb_context *tdb);
+
+/**
+ * @brief Get the tdb flags set during open.
+ *
+ * @param[in]  tdb      The database to get the flags form.
+ *
+ * @return              The flags set to on the database.
+ */
 int tdb_get_flags(struct tdb_context *tdb);
+
+/**
+ * @brief Add flags to the database.
+ *
+ * @param[in]  tdb      The database to add the flags.
+ *
+ * @param[in]  flag     The tdb flags to add.
+ */
 void tdb_add_flags(struct tdb_context *tdb, unsigned flag);
+
+/**
+ * @brief Remove flags from the database.
+ *
+ * @param[in]  tdb      The database to remove the flags.
+ *
+ * @param[in]  flag     The tdb flags to remove.
+ */
 void tdb_remove_flags(struct tdb_context *tdb, unsigned flag);
+
+/**
+ * @brief Enable sequence number handling on an open tdb.
+ *
+ * @param[in]  tdb      The database to enable sequence number handling.
+ *
+ * @see tdb_get_seqnum()
+ */
 void tdb_enable_seqnum(struct tdb_context *tdb);
+
+/**
+ * @brief Increment the tdb sequence number.
+ *
+ * This only works if the tdb has been opened using the TDB_SEQNUM flag or
+ * enabled useing tdb_enable_seqnum().
+ *
+ * @param[in]  tdb      The database to increment the sequence number.
+ *
+ * @see tdb_enable_seqnum()
+ * @see tdb_get_seqnum()
+ */
 void tdb_increment_seqnum_nonblock(struct tdb_context *tdb);
+
+/**
+ * @brief Create a hash of the key.
+ *
+ * @param[in]  key      The key to hash
+ *
+ * @return              The hash.
+ */
 unsigned int tdb_jenkins_hash(TDB_DATA *key);
+
+/**
+ * @brief Check the consistency of the database.
+ *
+ * This check the consistency of the database calling back the check function
+ * (if non-NULL) on each record.  If some consistency check fails, or the
+ * supplied check function returns -1, tdb_check returns -1, otherwise 0.
+ *
+ * @note The logging function (if set) will be called with additional
+ * information on the corruption found.
+ *
+ * @param[in]  tdb      The database to check.
+ *
+ * @param[in]  check    The check function to use.
+ *
+ * @param[in]  private_data the private data to pass to the check function.
+ *
+ * @return              0 on success, -1 on error with error code set.
+ *
+ * @see tdb_error()
+ * @see tdb_errorstr()
+ */
 int tdb_check(struct tdb_context *tdb,
 	      int (*check) (TDB_DATA key, TDB_DATA data, void *private_data),
 	      void *private_data);
 
+/* @} ******************************************************************/
+
 /* Low level locking functions: use with care */
 int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
 int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key);