[Tarantool-patches] [PATCH v3 09/10] raft: introduce box.info.election

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Box.info.election returns a table of form:

    {
        state: <string>,
        term: <number>,
        vote: <instance ID>,
        leader: <instance ID>
    }

The fields correspond to the same named Raft concepts one to one.
This info dump is supposed to help with the tests, first of all.
And with investigation of problems in a real cluster.

The API doesn't mention 'Raft' on purpose, to keep it not
depending specifically on Raft, and not to confuse users who
don't know anything about Raft (even that it is about leader
election and synchronous replication).

Part of #1146
---
 src/box/lua/info.c   | 17 +++++++++++++++++
 test/box/info.result |  1 +
 2 files changed, 18 insertions(+)

diff --git a/src/box/lua/info.c b/src/box/lua/info.c
index 1c131caec..cac3fd475 100644
--- a/src/box/lua/info.c
+++ b/src/box/lua/info.c
@@ -49,6 +49,7 @@
 #include "main.h"
 #include "version.h"
 #include "box/box.h"
+#include "box/raft.h"
 #include "lua/utils.h"
 #include "fiber.h"
 #include "tt_static.h"
@@ -577,6 +578,21 @@ lbox_info_listen(struct lua_State *L)
 	return 1;
 }
 
+static int
+lbox_info_election(struct lua_State *L)
+{
+	lua_createtable(L, 0, 4);
+	lua_pushstring(L, raft_state_strs[raft.state]);
+	lua_setfield(L, -2, "state");
+	luaL_pushuint64(L, raft.volatile_term);
+	lua_setfield(L, -2, "term");
+	lua_pushinteger(L, raft.volatile_vote);
+	lua_setfield(L, -2, "vote");
+	lua_pushinteger(L, raft.leader);
+	lua_setfield(L, -2, "leader");
+	return 1;
+}
+
 static const struct luaL_Reg lbox_info_dynamic_meta[] = {
 	{"id", lbox_info_id},
 	{"uuid", lbox_info_uuid},
@@ -595,6 +611,7 @@ static const struct luaL_Reg lbox_info_dynamic_meta[] = {
 	{"vinyl", lbox_info_vinyl},
 	{"sql", lbox_info_sql},
 	{"listen", lbox_info_listen},
+	{"election", lbox_info_election},
 	{NULL, NULL}
 };
 
diff --git a/test/box/info.result b/test/box/info.result
index 40eeae069..c8037818b 100644
--- a/test/box/info.result
+++ b/test/box/info.result
@@ -75,6 +75,7 @@ table.sort(t)
 t
 ---
 - - cluster
+  - election
   - gc
   - id
   - listen
-- 
2.21.1 (Apple Git-122.3)