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authorRonnie Sahlberg <ronniesahlberg@gmail.com>2009-05-25 17:04:42 +1000
committerStefan Metzmacher <metze@samba.org>2009-11-20 09:45:34 +0100
commit436b55db1ff238ec467b07a74b088f6fcfaf927c (patch)
tree1689f28b11031276ec4b9ce95509e5a780de4c9a /lib/tdb
parent85449b7bcc4bd7948bea38b5514a02357950a002 (diff)
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New attempt at TDB transaction nesting allow/disallow.
Make the default be that transaction is not allowed and any attempt to create a nested transaction will fail with TDB_ERR_NESTING. If an application can cope with transaction nesting and the implicit semantics of tdb_transaction_commit(), it can enable transaction nesting by using the TDB_ALLOW_NESTING flag. (cherry picked from ctdb commit 3e49e41c21eb8c53084aa8cc7fd3557bdd8eb7b6) Signed-off-by: Stefan Metzmacher <metze@samba.org>
Diffstat (limited to 'lib/tdb')
-rw-r--r--lib/tdb/common/transaction.c11
-rw-r--r--lib/tdb/include/tdb.h4
2 files changed, 14 insertions, 1 deletions
diff --git a/lib/tdb/common/transaction.c b/lib/tdb/common/transaction.c
index 035b4e1d54..501cd62b96 100644
--- a/lib/tdb/common/transaction.c
+++ b/lib/tdb/common/transaction.c
@@ -85,6 +85,13 @@
still available, but no transaction recovery area is used and no
fsync/msync calls are made.
+ - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
+ tdb_add_flags() transaction is enabled.
+ The default is that transaction nesting is not allowed and an attempt
+ to create a nested transaction will fail with TDB_ERR_NESTING.
+
+ Beware. when transactions are nested a transaction successfully
+ completed with tdb_transaction_commit() can be silently unrolled later.
*/
@@ -427,6 +434,10 @@ int tdb_transaction_start(struct tdb_context *tdb)
/* cope with nested tdb_transaction_start() calls */
if (tdb->transaction != NULL) {
+ if (!(tdb->flags & TDB_ALLOW_NESTING)) {
+ tdb->ecode = TDB_ERR_NESTING;
+ return -1;
+ }
tdb->transaction->nesting++;
TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
tdb->transaction->nesting));
diff --git a/lib/tdb/include/tdb.h b/lib/tdb/include/tdb.h
index e849f20641..5cc1eecdd1 100644
--- a/lib/tdb/include/tdb.h
+++ b/lib/tdb/include/tdb.h
@@ -48,11 +48,13 @@ extern "C" {
#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 */
/* 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_NOEXIST, TDB_ERR_EINVAL, TDB_ERR_RDONLY,
+ TDB_ERR_NESTING};
/* debugging uses one of the following levels */
enum tdb_debug_level {TDB_DEBUG_FATAL = 0, TDB_DEBUG_ERROR,