tdb: Add new function tdb_transaction_active()

This will allow callers to avoid their own reference counting of transactions.

Additionally, this will always line up with the acutal transaction state, even
in the error cases where tdb can cancel the transaction

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

3 files changed, 29 insertions, 0 deletions

diff --git a/lib/tdb/common/transaction.c b/lib/tdb/common/transaction.c
index 420e754d9b6..9b975eaa047 100644
--- a/lib/tdb/common/transaction.c
+++ b/lib/tdb/common/transaction.c
@@ -412,6 +412,14 @@ static const struct tdb_methods transaction_methods = {
 	transaction_expand_file,
 };
 
+/*
+ * Is a transaction currently active on this context?
+ *
+ */
+_PUBLIC_ bool tdb_transaction_active(struct tdb_context *tdb)
+{
+	return (tdb->transaction != NULL);
+}
 
 /*
   start a tdb transaction. No token is returned, as only a single
diff --git a/lib/tdb/include/tdb.h b/lib/tdb/include/tdb.h
index 4bfa1a4dd85..535f07ac00a 100644
--- a/lib/tdb/include/tdb.h
+++ b/lib/tdb/include/tdb.h
@@ -651,6 +651,24 @@ tdb_log_func tdb_log_fn(struct tdb_context *tdb);
 void *tdb_get_logging_private(struct tdb_context *tdb);
 
 /**
+ * @brief Is a transaction active?
+ *
+ * It is helpful for the application to know if a transaction is
+ * active, rather than needing to maintain an application-level reference
+ * count.
+ *
+ * @param[in]  tdb      The database to start the transaction.
+ *
+ * @return              true if there is a transaction active, false otherwise
+ *
+ * @see tdb_transaction_start()
+ * @see tdb_transaction_prepare_commit()
+ * @see tdb_transaction_commit()
+ * @see tdb_transaction_cancel()
+ */
+bool tdb_transaction_active(struct tdb_context *tdb);
+
+/**
  * @brief Start a transaction.
  *
  * All operations after the transaction start can either be committed with
diff --git a/lib/tdb/test/run-traverse-in-transaction.c b/lib/tdb/test/run-traverse-in-transaction.c
index 17d64129642..d187b9b58b8 100644
--- a/lib/tdb/test/run-traverse-in-transaction.c
+++ b/lib/tdb/test/run-traverse-in-transaction.c
@@ -63,7 +63,9 @@ int main(int argc, char *argv[])
 
 	ok1(external_agent_operation(agent, OPEN, tdb_name(tdb)) == SUCCESS);
 
+	ok1(tdb_transaction_active(tdb) == 0);
 	ok1(tdb_transaction_start(tdb) == 0);
+	ok1(tdb_transaction_active(tdb) == 1);
 	ok1(external_agent_operation(agent, TRANSACTION_START, tdb_name(tdb))
 	    == WOULD_HAVE_BLOCKED);
 	tdb_traverse(tdb, traverse, NULL);
@@ -77,6 +79,7 @@ int main(int argc, char *argv[])
 	ok1(external_agent_operation(agent, TRANSACTION_START, tdb_name(tdb))
 	    == WOULD_HAVE_BLOCKED);
 	ok1(tdb_transaction_commit(tdb) == 0);
+	ok1(tdb_transaction_active(tdb) == 0);
 	/* Now we should be fine. */
 	ok1(external_agent_operation(agent, TRANSACTION_START, tdb_name(tdb))
 	    == SUCCESS);