s4-dsdb: Try to avoid much of the time a db search for msDS-IntID

We search in the schema if we have already this intid (using dsdb_attribute_by_attributeID_id because
in the range 0x80000000 0xBFFFFFFFF, attributeID is a DSDB_ATTID_TYPE_INTID).
If so generate another random value.
If not check if the highest USN in the database for the schema partition is the
one that we know.
If so it means that's only this ldb context that is touching the schema in the database.
If not it means that's someone else has modified the database while we are doing our changes too
(this case should be very bery rare) in order to be sure do the search in the database.

1 files changed, 17 insertions, 0 deletions

diff --git a/source4/dsdb/samdb/ldb_modules/repl_meta_data.c b/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
index a558a64999..49fca5f376 100644
--- a/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
+++ b/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
@@ -751,6 +751,7 @@ static int replmd_add_fix_la(struct ldb_module *module, struct ldb_message_eleme
  */
 static int replmd_add(struct ldb_module *module, struct ldb_request *req)
 {
+	struct samldb_msds_intid_persistant *msds_intid_struct;
 	struct ldb_context *ldb;
         struct ldb_control *control;
 	struct replmd_replicated_request *ac;
@@ -1053,7 +1054,14 @@ static int replmd_add(struct ldb_module *module, struct ldb_request *req)
 	if (control) {
 		control->critical = 0;
 	}
+	if (ldb_dn_compare_base(ac->schema->base_dn, req->op.add.message->dn) != 0) {
 
+		/* Update the usn in the SAMLDB_MSDS_INTID_OPAQUE opaque */
+		msds_intid_struct = (struct samldb_msds_intid_persistant *) ldb_get_opaque(ldb, SAMLDB_MSDS_INTID_OPAQUE);
+		if (msds_intid_struct) {
+			msds_intid_struct->usn = ac->seq_num;
+		}
+	}
 	/* go on with the call chain */
 	return ldb_next_request(module, down_req);
 }
@@ -2294,6 +2302,7 @@ static int replmd_modify_handle_linked_attribs(struct ldb_module *module,
 
 static int replmd_modify(struct ldb_module *module, struct ldb_request *req)
 {
+	struct samldb_msds_intid_persistant *msds_intid_struct;
 	struct ldb_context *ldb;
 	struct replmd_replicated_request *ac;
 	struct ldb_request *down_req;
@@ -2426,6 +2435,14 @@ static int replmd_modify(struct ldb_module *module, struct ldb_request *req)
 		}
 	}
 
+	if (!ldb_dn_compare_base(ac->schema->base_dn, msg->dn)) {
+		/* Update the usn in the SAMLDB_MSDS_INTID_OPAQUE opaque */
+		msds_intid_struct = (struct samldb_msds_intid_persistant *) ldb_get_opaque(ldb, SAMLDB_MSDS_INTID_OPAQUE);
+		if (msds_intid_struct) {
+			msds_intid_struct->usn = ac->seq_num;
+		}
+	}
+
 	/* go on with the call chain */
 	return ldb_next_request(module, down_req);
 }