[ovs-dev] [PATCH] ovsdb-idl: Add function to set next_remote in jsonrpc session.

[Zhen Wang]

OVN SouthBound DB in clustered mode, when one raft node down and
online. All the ovn-controller clients will not migirate back which
cause RAFT DB clients unbalanced state.

This function provides a way to set the IDL jsonrpc session next_remote.
Which can let caller to set the next reconnect remote which can address
the unbalance issue with reconnect operation.

Notice that this function is not actually used anywhere in this patch.
This will be used by OVN, though, since OVN is the primary user of
clustered OVSDB.

Reported-at:https://mail.openvswitch.org/pipermail/ovs-discuss/2020-August/050518.html
Signed-off-by: Zhen Wang <zhewang at nvidia.com>
---
 lib/jsonrpc.c   | 12 ++++++++++++
 lib/jsonrpc.h   |  2 ++
 lib/ovsdb-idl.c |  9 +++++++++
 lib/ovsdb-idl.h |  1 +
 4 files changed, 24 insertions(+)

diff --git a/lib/jsonrpc.c b/lib/jsonrpc.c
index ecbc939fe..08971ee94 100644
--- a/lib/jsonrpc.c
+++ b/lib/jsonrpc.c
@@ -1250,3 +1250,15 @@ jsonrpc_session_set_dscp(struct jsonrpc_session *s, uint8_t dscp)
         jsonrpc_session_force_reconnect(s);
     }
 }
+
+/* Sets the next remote offset for next jsonrpc session reconnect. */
+void
+jsonrpc_session_set_next_remote(struct jsonrpc_session *s, const char *name)
+{
+    for (size_t i = 0; i < s->remotes.n; i++) {
+        if (!strcmp(s->remotes.names[i], name)) {
+            s->next_remote = i;
+            break;
+        }
+    }
+}
diff --git a/lib/jsonrpc.h b/lib/jsonrpc.h
index a44114e8d..f81d62047 100644
--- a/lib/jsonrpc.h
+++ b/lib/jsonrpc.h
@@ -140,6 +140,8 @@ void jsonrpc_session_set_probe_interval(struct jsonrpc_session *,
                                         int probe_interval);
 void jsonrpc_session_set_dscp(struct jsonrpc_session *,
                               uint8_t dscp);
+void jsonrpc_session_set_next_remote(struct jsonrpc_session *,
+                              const char *);
 const char *jsonrpc_session_get_id(const struct jsonrpc_session *);
 
 #endif /* jsonrpc.h */
diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c
index d8f221ca6..82f09bbe7 100644
--- a/lib/ovsdb-idl.c
+++ b/lib/ovsdb-idl.c
@@ -557,6 +557,15 @@ ovsdb_idl_set_remote(struct ovsdb_idl *idl, const char *remote, bool retry)
     }
 }
 
+/* Set next remote offset for ovsdb_idl jsonrpc session.*/
+void
+ovsdb_idl_set_next_remote(struct ovsdb_idl *idl, const char *remote)
+{
+    if (idl->session) {
+        jsonrpc_session_set_next_remote(idl->session, remote);
+    }
+}
+
 /* Set whether the order of remotes should be shuffled, when there
  * are more than one remotes.  The setting doesn't take effect
  * until the next time when ovsdb_idl_set_remote() is called. */
diff --git a/lib/ovsdb-idl.h b/lib/ovsdb-idl.h
index c56cd19b1..01bb9a409 100644
--- a/lib/ovsdb-idl.h
+++ b/lib/ovsdb-idl.h
@@ -63,6 +63,7 @@ struct ovsdb_idl *ovsdb_idl_create(const char *remote,
 struct ovsdb_idl *ovsdb_idl_create_unconnected(
     const struct ovsdb_idl_class *, bool monitor_everything_by_default);
 void ovsdb_idl_set_remote(struct ovsdb_idl *, const char *, bool);
+void ovsdb_idl_set_next_remote(struct ovsdb_idl *, const char *);
 void ovsdb_idl_set_shuffle_remotes(struct ovsdb_idl *, bool);
 void ovsdb_idl_reset_min_index(struct ovsdb_idl *);
 void ovsdb_idl_destroy(struct ovsdb_idl *);
-- 
2.20.1