db: add ring buffer for DB query

This patch adds an optional ring buffer option which modify
the way database queries are made. The main thread is only handling
kernel message reading and query formatting. The SQL request is made
in a separate dedicated thread.
The idea is to try to avoid buffer overrun by minimizing the time
requested to treat kernel message. Doing synchronous SQL request, as
it was made before was causing a delay which could cause some messages
to be lost in case of burst from kernel side.

1 files changed, 4 insertions, 0 deletions

diff --git a/ulogd.conf.in b/ulogd.conf.in
index 3e5e648..11a56d6 100644
--- a/ulogd.conf.in
+++ b/ulogd.conf.in
@@ -233,6 +233,10 @@ pass="changeme"
 procedure="INSERT_PACKET_FULL"
 #backlog_memcap=1000000
 #backlog_oneshot_requests=10
+# If superior to 1 a thread dedicated to SQL request execution
+# is created. The value stores the number of SQL request to keep
+# in the ring buffer
+#ring_buffer_size=1000
 
 [pgsql2]
 db="nulog"