db-ctl-base: Use partial map/set updates for last add/set commands.

Currently, command to add one item into a large set generates the
transaction with the full new content of that set plus 'wait'
operation for the full old content of that set.  So, if we're adding
one new load-balancer into a load-balancer group in OVN using
ovn-nbctl, transaction will include all the existing load-balancers
from that groups twice.

IDL supports partial updates for sets and maps.  The problem with that
is changes are not visible to the IDL user until the transaction
is committed.  That will cause problems for chained ctl commands.
However, we still can optimize the very last command in the list.
It makes sense to do, since it's a common case for manual invocations.

Updating the 'add' command as well as 'set' for a case where we're
actually adding one new element to the map.

One downside is that we can't check the set size without examining
it and checking for duplicates, so allowing the transaction to be
sent and constraints to be checked on the server side in that case.

Not touching 'remove' operation for now, since removals may have
different type, e.g. if elements from the map are removed by the key.
The function will likely need to be fully re-written to accommodate
all the corner cases.

Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/vtep/vtep-ctl.c b/vtep/vtep-ctl.c
index 99c4adcd5..e5d99714d 100644
--- a/vtep/vtep-ctl.c
+++ b/vtep/vtep-ctl.c
@@ -2207,9 +2207,9 @@ static const struct ctl_table_class tables[VTEPREC_N_TABLES] = {
 
 static void
 vtep_ctl_context_init_command(struct vtep_ctl_context *vtepctl_ctx,
-                              struct ctl_command *command)
+                              struct ctl_command *command, bool last_command)
 {
-    ctl_context_init_command(&vtepctl_ctx->base, command);
+    ctl_context_init_command(&vtepctl_ctx->base, command, last_command);
     vtepctl_ctx->verified_ports = false;
 
 }
@@ -2304,7 +2304,8 @@ do_vtep_ctl(const char *args, struct ctl_command *commands,
     }
     vtep_ctl_context_init(&vtepctl_ctx, NULL, idl, txn, vtep_global, symtab);
     for (c = commands; c < &commands[n_commands]; c++) {
-        vtep_ctl_context_init_command(&vtepctl_ctx, c);
+        vtep_ctl_context_init_command(&vtepctl_ctx, c,
+                                      c == &commands[n_commands - 1]);
         if (c->syntax->run) {
             (c->syntax->run)(&vtepctl_ctx.base);
         }