r22775: For the cluster code I've developed a wrapper around tdb to put different

database backends in place dynamically.

The main abstractions are db_context and db_record, it should be mainly
self-describing, see include/dbwrap.h.  You open the db just as you would open
a tdb, this time with db_open(). If you want to fetch a record, just do the
db->fetch() call, if you want to do operations on it, you need to get it with
fetch_locked().

I added dbwrap_file.c (not heavily tested lately) as an example for what can
be done with that abstraction, uses a file per key. So if anybody is willing
to shape that up, we might have a chance on reiserfs again.... :-)

This abstraction works fine for brlock.tdb, locking.tdb, connections.tdb and
sessionid.tdb. It should work fine for the others as well, I just did not yet
get around to convert them.

If nobody loudly screams NO, then I will import the code that uses this soon.

Volker
(This used to be commit e9d7484ca246cfca4a1fd23be35edc2783136ebe)

1 files changed, 61 insertions, 0 deletions

diff --git a/source3/lib/dbwrap.c b/source3/lib/dbwrap.c
new file mode 100644
index 0000000000..9f74a9eb48
--- /dev/null
+++ b/source3/lib/dbwrap.c
@@ -0,0 +1,61 @@
+/* 
+   Unix SMB/CIFS implementation.
+   Database interface wrapper
+   Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2006
+
+   Major code contributions from Aleksey Fedoseev (fedoseev@ru.ibm.com)
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+
+/*
+ * Fall back using fetch_locked if no genuine fetch operation is provided
+ */
+
+static int dbwrap_fallback_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
+				 TDB_DATA key, TDB_DATA *data)
+{
+	struct db_record *rec;
+
+	if (!(rec = db->fetch_locked(db, mem_ctx, key))) {
+		return -1;
+	}
+
+	data->dsize = rec->value.dsize;
+	data->dptr = talloc_move(mem_ctx, &rec->value.dptr);
+	TALLOC_FREE(rec);
+	return 0;
+}
+
+struct db_context *db_open(TALLOC_CTX *mem_ctx,
+			   const char *name,
+			   int hash_size, int tdb_flags,
+			   int open_flags, mode_t mode)
+{
+	struct db_context *result = NULL;
+
+	if (result == NULL) {
+		result = db_open_tdb(mem_ctx, name, hash_size,
+				     tdb_flags, open_flags, mode);
+	}
+
+	if ((result != NULL) && (result->fetch == NULL)) {
+		result->fetch = dbwrap_fallback_fetch;
+	}
+
+	return result;
+}