controller-vtep: add support to configure inactivity probe interval

This patch adds new configuration option for ovn-controller-vtep service
to supply OVSDB (only OVN_Southbound DB) probe interval value.

It can be configured through Hardware_Vtep database, Global table, column
other_config:ovn-remote-probe-interval.

Signed-off-by: Vladislav Odintsov <odivlad@gmail.com>
Signed-off-by: Numan Siddique <numans@ovn.org>

controller-vtep/ovn-controller-vtep.8.xml

@@ -96,6 +96,20 @@
         connected <code>hardware_vtep</code> database changes.
         The default value is considered false if this option is not defined.
       </dd>
+
+      <dt><code>other_config:ovn-remote-probe-interval</code></dt>
+      <dd>
+        <p>
+          The inactivity probe interval of the connection to the OVN Southbound
+          database, in milliseconds. If the value is zero, it disables the
+          connection keepalive feature.
+        </p>
+
+        <p>
+          If the value is nonzero, then it will be forced to a value of at
+          least 1000 ms.
+        </p>
+      </dd>
     </dl>
     </p>
 </manpage>

controller-vtep/ovn-controller-vtep.c

@@ -31,6 +31,7 @@
 #include "openvswitch/poll-loop.h"
 #include "simap.h"
 #include "ovsdb-idl.h"
+#include "smap.h"
 #include "stream.h"
 #include "stream-ssl.h"
 #include "unixctl.h"
@@ -88,6 +89,20 @@ check_northd_version(struct ovsdb_idl *vtep_idl, struct ovsdb_idl *ovnsb_idl,
     return true;
 }
 
+/* Set probe interval, based on user configuration and the remote. */
+static void
+update_idl_probe_interval(struct ovsdb_idl *ovn_sb_idl,
+                          struct ovsdb_idl *vtep_idl)
+{
+    const struct vteprec_global *cfg = vteprec_global_first(vtep_idl);
+    int interval = -1;
+    if (cfg) {
+        interval = smap_get_int(&cfg->other_config,
+                                "ovn-remote-probe-interval", interval);
+    }
+    set_idl_probe_interval(ovn_sb_idl, ovnsb_remote, interval);
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -179,6 +194,8 @@ main(int argc, char *argv[])
             simap_destroy(&usage);
         }
 
+        update_idl_probe_interval(ovnsb_idl_loop.idl, vtep_idl_loop.idl);
+
         if (ovsdb_idl_has_ever_connected(ovnsb_idl_loop.idl) &&
             ovsdb_idl_has_ever_connected(vtep_idl_loop.idl) &&
             check_northd_version(vtep_idl_loop.idl, ovnsb_idl_loop.idl,