From: Michael Adam <obnox@samba.org>
Date: Wed, 13 Jan 2010 22:53:54 +0000 (+0100)
Subject: s3:dbwrap_ctdb: exit early when nothing has been written in transaction_commit.
X-Git-Url: http://git.samba.org/?a=commitdiff_plain;h=c311697aded87ce624d40cbf14e05d6e6377c257;p=abartlet%2Fsamba.git%2F.git

s3:dbwrap_ctdb: exit early when nothing has been written in transaction_commit.

This skips update of the __db_sequence_number__ record when nothing else has
been written. There are transactions that are just openend and then nothing
is written until transaction_commit is called. This is for instance the case
with registry initialization routines: They start a transaction and only
write somthing when the registry has not been initialized yet.
So this change will skip many db_seqnum bumps and TRANS3_COMMIT roundtrips.

Michael
---

diff --git a/source3/lib/dbwrap_ctdb.c b/source3/lib/dbwrap_ctdb.c
index c0b5fd51ed5..79c4c0ce420 100644
--- a/source3/lib/dbwrap_ctdb.c
+++ b/source3/lib/dbwrap_ctdb.c
@@ -763,6 +763,15 @@ static int db_ctdb_transaction_commit(struct db_context *db)
 		return 0;
 	}
 
+	if (h->m_write == NULL) {
+		/*
+		 * No changes were made, so don't change the seqnum,
+		 * don't push to other node, just exit with success.
+		 */
+		ret = 0;
+		goto done;
+	}
+
 	DEBUG(5,(__location__ " Commit transaction on db 0x%08x\n", ctx->db_id));
 
 	/*
@@ -790,11 +799,6 @@ static int db_ctdb_transaction_commit(struct db_context *db)
 	}
 
 again:
-	if (h->m_write == NULL) {
-		/* no changes were made, potentially after a retry */
-		goto done;
-	}
-
 	/* tell ctdbd to commit to the other nodes */
 	rets = ctdbd_control_local(messaging_ctdbd_connection(),
 				   CTDB_CONTROL_TRANS3_COMMIT,