expanded the tdb documentation

(This used to be commit efb4fbcca876ec661af0d72d4df2f04f36d4dd76)

1 files changed, 110 insertions, 0 deletions

diff --git a/source3/tdb/README b/source3/tdb/README
index 3c0059c5cb7..f4fa30dc640 100644
--- a/source3/tdb/README
+++ b/source3/tdb/README
@@ -1,3 +1,7 @@
+tdb - a trivial database system
+tridge@linuxcare.com December 1999
+==================================
+
 This is a simple database API. It was inspired by the realisation that
 in Samba we have several ad-hoc bits of code that essentially
 implement small databases for sharing structures between parts of
@@ -38,3 +42,109 @@ The interface is very similar to gdbm except for the following:
 - no tdbm_sync() function. No operations are cached in the library anyway
 - added a tdb_traverse() function for traversing the whole database
 
+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.
+
+here is a full list of tdb functions with brief descriptions.
+
+
+----------------------------------------------------------------------
+TDB_CONTEXT *tdb_open(char *name, int hash_size, int flags, mode_t mode);
+
+   open the database, creating it if necessary 
+
+   The flags and mode are passed straight to the open call on the database
+   file. A flags value of O_WRONLY is invalid
+
+   The hash size is advisory, use zero for a default value. 
+
+   return is NULL on error
+
+----------------------------------------------------------------------
+int tdb_close(TDB_CONTEXT *tdb);
+
+   close a database
+
+----------------------------------------------------------------------
+int tdb_update(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf);
+
+   update an entry in place - this only works if the new data size
+   is <= the old data size and the key exists.
+   on failure return -1
+
+----------------------------------------------------------------------
+TDB_DATA tdb_fetch(TDB_CONTEXT *tdb, TDB_DATA key);
+
+   fetch an entry in the database given a key 
+   if the return value has a null dptr then a error occurred
+
+   caller must free the resulting data
+
+----------------------------------------------------------------------
+int tdb_exists(TDB_CONTEXT *tdb, TDB_DATA key);
+
+   check if an entry in the database exists 
+
+   note that 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
+
+----------------------------------------------------------------------
+int tdb_traverse(TDB_CONTEXT *tdb, int (*fn)(TDB_CONTEXT *tdb,
+                 TDB_DATA key, TDB_DATA dbuf));
+
+   traverse the entire database - calling fn(tdb, key, data) on each element.
+
+   return -1 on error or the record count traversed
+
+   if fn is NULL then it is not called
+
+   a non-zero return value from fn() indicates that the traversal should stop
+
+----------------------------------------------------------------------
+TDB_DATA tdb_firstkey(TDB_CONTEXT *tdb);
+
+   find the first entry in the database and return its key
+
+   the caller must free the returned data
+
+----------------------------------------------------------------------
+TDB_DATA tdb_nextkey(TDB_CONTEXT *tdb, TDB_DATA key);
+
+   find the next entry in the database, returning its key
+
+   the caller must free the returned data
+
+----------------------------------------------------------------------
+int tdb_delete(TDB_CONTEXT *tdb, TDB_DATA key);
+
+   delete an entry in the database given a key
+
+----------------------------------------------------------------------
+int tdb_store(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, int flag);
+
+   store an element in the database, replacing any existing element
+   with the same key 
+
+   return 0 on success, -1 on failure
+
+----------------------------------------------------------------------
+int tdb_writelock(TDB_CONTEXT *tdb);
+
+   lock the database. If we already have it locked then don't do anything
+
+----------------------------------------------------------------------
+int tdb_writeunlock(TDB_CONTEXT *tdb);
+   unlock the database
+
+----------------------------------------------------------------------
+int tdb_lockchain(TDB_CONTEXT *tdb, TDB_DATA key);
+
+   lock one hash chain. This is meant to be used to reduce locking
+   contention - it cannot guarantee how many records will be locked
+
+----------------------------------------------------------------------
+int tdb_unlockchain(TDB_CONTEXT *tdb, TDB_DATA key);
+
+   unlock one hash chain