Re: [Tarantool-patches] [PATCH v2] replication: add box.info.replication_anon

[Serge Petrenko <sergepetrenko@tarantool.org>]

> 24 апр. 2020 г., в 19:39, Konstantin Osipov <kostja.osipov@gmail.com> написал(а):
> 
> * Serge Petrenko <sergepetrenko@tarantool.org> [20/04/24 19:33]:
>> Closes #4900
>> 
>> @TarantoolBot document
>> Title: add new field to box.info: replication_anon
>> 
>> It is now possible to list all the anonymous replicas following the
>> instance with a call to `box.info.replication_anon()`
>> The output is similar to the one produced by `box.info.replication` with
>> an exception that anonymous replicas are indexed by their uuid strings
>> rather then server ids, since server ids have no meaning for anonymous
>> replicas.
>> 
>> Example:
>> ```
>> tarantool> box.info.replication_anon
>> ---
>> - []
>> ...
>> 
>> tarantool> box.info.replication_anon()
> 
> Why do you have to use ()? Isn't it inconsistent with
> box.info.replication?
> 

It’s done in order to shorten `box.info` output. There may be lots
of anonymous replicas following a master. I’ve updated the commit message
correspondingly.

It was also agreed verbally, that we should output the number of anonymous
replicas following a master on `box.info.replication_anon` without the `()`.

The diff is below.

diff --git a/src/box/lua/info.c b/src/box/lua/info.c
index c4f90bda1..e7318fcd1 100644
--- a/src/box/lua/info.c
+++ b/src/box/lua/info.c
@@ -248,6 +248,10 @@ lbox_info_replication_anon(struct lua_State *L)
 	 */
 	lua_newtable(L);
 
+	lua_pushliteral(L, "count");
+	lua_pushinteger(L, replicaset.anon_count);
+	lua_settable(L, -3);
+
 	lua_newtable(L); /* metatable */
 
 	lua_pushstring(L, "__call");
diff --git a/src/box/replication.cc b/src/box/replication.cc
index 7c10fb6f2..1b61c92c0 100644
--- a/src/box/replication.cc
+++ b/src/box/replication.cc
@@ -219,6 +219,7 @@ replicaset_add_anon(const struct tt_uuid *replica_uuid)
 	replica->uuid = *replica_uuid;
 	replica_hash_insert(&replicaset.hash, replica);
 	replica->anon = true;
+	replicaset.anon_count++;
 	return replica;
 }
 
@@ -909,6 +910,8 @@ replica_on_relay_stop(struct replica *replica)
 			 * replicas.
 			 */
 			assert(replica->applier == NULL);
+			assert(replicaset.anon_count > 0);
+			replicaset.anon_count--;
 		}
 	}
 	if (replica_is_orphan(replica)) {
diff --git a/src/box/replication.h b/src/box/replication.h
index 9df91e611..93a25c8a7 100644
--- a/src/box/replication.h
+++ b/src/box/replication.h
@@ -203,6 +203,8 @@ struct replicaset {
 	 * from a remote master.
 	 */
 	bool is_joining;
+	/* A number of anonymous replicas following this instance. */
+	int anon_count;
 	/** Applier state. */
 	struct {
 		/**
diff --git a/test/replication/anon.result b/test/replication/anon.result
index f3f9c60ed..a7e244d3f 100644
--- a/test/replication/anon.result
+++ b/test/replication/anon.result
@@ -154,7 +154,7 @@ test_run:cmd('switch default')
 -- Test box.info.replication_anon.
 box.info.replication_anon
  | ---
- | - []
+ | - count: 1
  | ...
 #box.info.replication_anon()
  | ---


> 
> -- 
> Konstantin Osipov, Moscow, Russia
> https://scylladb.com

--
Serge Petrenko
sergepetrenko@tarantool.org