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diff --git a/tdb/README b/tdb/README deleted file mode 100644 index fac3eacb4d..0000000000 --- a/tdb/README +++ /dev/null @@ -1,167 +0,0 @@ -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 -Samba. As I was about to add another I realised that a generic -database module was called for to replace all the ad-hoc bits. - -I based the interface on gdbm. I couldn't use gdbm as we need to be -able to have multiple writers to the databases at one time. - -Compilation ------------ - -add HAVE_MMAP=1 to use mmap instead of read/write -add TDB_DEBUG=1 for verbose debug info -add NOLOCK=1 to disable locking code - -Testing -------- - -Compile tdbtest.c and link with gdbm for testing. tdbtest will perform -identical operations via tdb and gdbm then make sure the result is the -same - -Also included is tdbtool, which allows simple database manipulation -on the commandline. - -tdbtest and tdbtool are not built as part of Samba, but are included -for completeness. - -Interface ---------- - -The interface is very similar to gdbm except for the following: - -- different open interface. The tdb_open call is more similar to a - traditional open() -- no tdbm_reorganise() function -- 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 tdb_flags, - int open_flags, mode_t mode) - - open the database, creating it if necessary - - The open_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 - - possible tdb_flags are: - TDB_CLEAR_IF_FIRST - clear database if we are the only one with it open - TDB_INTERNAL - don't use a file, instaed store the data in - memory. The filename is ignored in this case. - TDB_NOLOCK - don't do any locking - TDB_NOMMAP - don't use mmap - ----------------------------------------------------------------------- -char *tdb_error(TDB_CONTEXT *tdb); - - return a error string for the last tdb 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, void *state), void *state); - - traverse the entire database - calling fn(tdb, key, data, state) 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 - - If flag==TDB_INSERT then don't overwrite an existing entry - If flag==TDB_MODIFY then don't create a new entry - - 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 |