replication: broadcast instance name in the ballot

Node's ballot contains all the information necessary to choose it a
bootstrap leader. Since the bootstrap_leader configuration option will
allow specifying bootstrap leader's name, we have to broadcast the name
in node's ballot.

Prerequisite tarantool#8539

NO_CHANGELOG=not user-visible

@TarantoolBot document
Title: new field in node's BALLOT: IPROTO_BALLOT_INSTANCE_NAME

The node's ballot (IPROTO_BALLOT) receives a new field:
the name of the node (the same as in box.cfg.instance_name or
box.info.name):
Key: IPROTO_BALLOT_INSTANCE_NAME = 0x0a
Value: MP_STR, representing the instance name.

src/box/box.cc

@@ -4426,6 +4426,15 @@ box_process_vote(struct ballot *ballot)
 	vclock_copy(&ballot->vclock, &replicaset.vclock);
 	vclock_copy(&ballot->gc_vclock, &gc.vclock);
 	ballot->bootstrap_leader_uuid = bootstrap_leader_uuid;
+	if (*INSTANCE_NAME != '\0') {
+		strlcpy(ballot->instance_name, INSTANCE_NAME,
+			NODE_NAME_SIZE_MAX);
+	} else if (*cfg_instance_name != '\0') {
+		strlcpy(ballot->instance_name, cfg_instance_name,
+			NODE_NAME_SIZE_MAX);
+	} else {
+		*ballot->instance_name = '\0';
+	}
 	int i = 0;
 	replicaset_foreach(replica) {
 		if (replica->id != 0)

src/box/iproto_constants.h

@@ -263,6 +263,7 @@ extern const char *iproto_metadata_key_strs[];
 	_(CAN_LEAD, 0x07)						\
 	_(BOOTSTRAP_LEADER_UUID, 0x08)					\
 	_(REGISTERED_REPLICA_UUIDS, 0x09)				\
+	_(INSTANCE_NAME, 0x0a)						\
 
 #define IPROTO_BALLOT_KEY_MEMBER(s, v) IPROTO_BALLOT_ ## s = v,
 

src/box/xrow.c

@@ -544,7 +544,7 @@ mp_sizeof_ballot_max(const struct ballot *ballot)
 {
 	int registered_uuids_size = ballot->registered_replica_uuids_size;
 	return mp_sizeof_map(1) + mp_sizeof_uint(IPROTO_BALLOT) +
-	       mp_sizeof_map(9) + mp_sizeof_uint(IPROTO_BALLOT_IS_RO_CFG) +
+	       mp_sizeof_map(10) + mp_sizeof_uint(IPROTO_BALLOT_IS_RO_CFG) +
 	       mp_sizeof_bool(ballot->is_ro_cfg) +
 	       mp_sizeof_uint(IPROTO_BALLOT_IS_RO) +
 	       mp_sizeof_bool(ballot->is_ro) +
@@ -560,6 +560,8 @@ mp_sizeof_ballot_max(const struct ballot *ballot)
 	       mp_sizeof_bool(ballot->can_lead) +
 	       mp_sizeof_uint(IPROTO_BALLOT_BOOTSTRAP_LEADER_UUID) +
 	       mp_sizeof_str(UUID_STR_LEN) +
+	       mp_sizeof_uint(IPROTO_BALLOT_INSTANCE_NAME) +
+	       mp_sizeof_str(NODE_NAME_LEN_MAX) +
 	       mp_sizeof_uint(IPROTO_BALLOT_REGISTERED_REPLICA_UUIDS) +
 	       mp_sizeof_array(registered_uuids_size) +
 	       registered_uuids_size * mp_sizeof_str(UUID_STR_LEN);
@@ -571,7 +573,8 @@ mp_encode_ballot(char *data, const struct ballot *ballot)
 {
 	data = mp_encode_map(data, 1);
 	data = mp_encode_uint(data, IPROTO_BALLOT);
-	data = mp_encode_map(data, 9);
+	bool has_name = *ballot->instance_name != '\0';
+	data = mp_encode_map(data, has_name ? 10 : 9);
 	data = mp_encode_uint(data, IPROTO_BALLOT_IS_RO_CFG);
 	data = mp_encode_bool(data, ballot->is_ro_cfg);
 	data = mp_encode_uint(data, IPROTO_BALLOT_IS_RO);
@@ -588,6 +591,10 @@ mp_encode_ballot(char *data, const struct ballot *ballot)
 	data = mp_encode_bool(data, ballot->can_lead);
 	data = mp_encode_uint(data, IPROTO_BALLOT_BOOTSTRAP_LEADER_UUID);
 	data = xrow_encode_uuid(data, &ballot->bootstrap_leader_uuid);
+	if (has_name) {
+		data = mp_encode_uint(data, IPROTO_BALLOT_INSTANCE_NAME);
+		data = mp_encode_str0(data, ballot->instance_name);
+	}
 	data = mp_encode_uint(data, IPROTO_BALLOT_REGISTERED_REPLICA_UUIDS);
 	data = mp_encode_array(data, ballot->registered_replica_uuids_size);
 	for (int i = 0; i < ballot->registered_replica_uuids_size; i++) {
@@ -1791,6 +1798,7 @@ xrow_decode_ballot(const struct xrow_header *row, struct ballot *ballot)
 	ballot->is_booted = true;
 	vclock_create(&ballot->vclock);
 	vclock_create(&ballot->gc_vclock);
+	*ballot->instance_name = '\0';
 
 	if (row->bodycnt == 0)
 		goto err;
@@ -1889,6 +1897,12 @@ mp_decode_ballot(const char *data, const char *end,
 			*is_empty = false;
 			break;
 		}
+		case IPROTO_BALLOT_INSTANCE_NAME:
+			if (xrow_decode_node_name(&data,
+						  ballot->instance_name) != 0) {
+				return -1;
+			}
+			break;
 		case IPROTO_BALLOT_REGISTERED_REPLICA_UUIDS: {
 			if (mp_typeof(*data) != MP_ARRAY)
 				return -1;

src/box/xrow.h

@@ -509,6 +509,8 @@ struct ballot {
 	struct vclock gc_vclock;
 	/** The uuid of the instance this node considers a bootstrap leader. */
 	struct tt_uuid bootstrap_leader_uuid;
+	/** The name of this node. */
+	char instance_name[NODE_NAME_LEN_MAX];
 	/** Replica uuids registered in the replica set. */
 	struct tt_uuid registered_replica_uuids[VCLOCK_MAX];
 	/** Number of replicas registered in the replica set. */

test/box-luatest/builtin_events_test.lua

@@ -414,4 +414,8 @@ g.test_internal_ballot = function(cg)
     expected[ballot_key.CAN_LEAD] = true
     expected[ballot_key.IS_RO] = true
     cg.replica:exec(wait_ballot_updated_to, {expected})
+    cg.replica:update_box_cfg{instance_name='replica-name'}
+    expected[ballot_key.INSTANCE_NAME] = 'replica-name'
+    expected[ballot_key.VCLOCK] = cg.master:get_vclock()
+    cg.replica:exec(wait_ballot_updated_to, {expected})
 end

test/box-luatest/gh_7894_export_iproto_constants_and_features_test.lua

@@ -107,6 +107,7 @@ local reference_table = {
         CAN_LEAD = 0x07,
         BOOTSTRAP_LEADER_UUID = 0x08,
         REGISTERED_REPLICA_UUIDS = 0x09,
+        INSTANCE_NAME = 0x10,
     },
 
     -- `iproto_type` enumeration.