feat(bpapi): Verify emqx cluster RPC

apps/emqx/src/bpapi/emqx_bpapi_static_checks.erl

@@ -48,6 +48,8 @@
 -define(IGNORED_MODULES, "emqx_rpc").
 %% List of known RPC backend modules:
 -define(RPC_MODULES, "gen_rpc, erpc, rpc, emqx_rpc").
+%% List of known functions also known to do RPC:
+-define(RPC_FUNCTIONS, "emqx_cluster_rpc:multicall/3, emqx_cluster_rpc:multicall/5").
 %% List of functions in the RPC backend modules that we can ignore:
 -define(IGNORED_RPC_CALLS, "gen_rpc:nodes/0").
 
@@ -206,7 +208,7 @@ prepare(#{reldir := RelDir, plt := PLT}) ->
 
 find_remote_calls(_Opts) ->
     Query = "XC | (A - [" ?IGNORED_APPS "]:App - [" ?IGNORED_MODULES "] : Mod)
-               || ([" ?RPC_MODULES "] : Mod - " ?IGNORED_RPC_CALLS ")",
+               || (([" ?RPC_MODULES "] : Mod + [" ?RPC_FUNCTIONS "]) - " ?IGNORED_RPC_CALLS ")",
     {ok, Calls} = xref:q(?XREF, Query),
     ?INFO("Calls to RPC modules ~p", [Calls]),
     {Callers, _Callees} = lists:unzip(Calls),

apps/emqx/src/bpapi/emqx_bpapi_trans.erl

@@ -158,6 +158,11 @@ extract_mfa(?BACKEND(RPC, CallOrCast), [_Node, M, F, A]) when ?IS_RPC(RPC) ->
     {call_or_cast(CallOrCast), M, F, A};
 extract_mfa(?BACKEND(RPC, CallOrCast), [_Node, M, F, A, _Timeout]) when ?IS_RPC(RPC) ->
     {call_or_cast(CallOrCast), M, F, A};
+%% emqx_cluster_rpc:
+extract_mfa(?BACKEND(emqx_cluster_rpc, multicall), [M, F, A]) ->
+    {call, M, F, A};
+extract_mfa(?BACKEND(emqx_cluster_rpc, multicall), [M, F, A, _RequiredNum, _Timeout]) ->
+    {call, M, F, A};
 extract_mfa(_, _) ->
     error("unrecognized RPC call").
 

apps/emqx_conf/src/emqx_cluster_rpc.erl

@@ -18,6 +18,10 @@
 
 %% API
 -export([start_link/0, mnesia/1]).
+
+%% Note: multicall functions are statically checked by
+%% `emqx_bapi_trans' and `emqx_bpapi_static_checks' modules. Don't
+%% forget to update it when adding or removing them here:
 -export([multicall/3, multicall/5, query/1, reset/0, status/0,
          skip_failed_commit/1, fast_forward_to_commit/2]).
 -export([get_node_tnx_id/1, latest_tnx_id/0]).