Remove extra check

rabbitmq · May 23, 2024 · 840f7ba · 840f7ba
1 parent e6bbd1a
commit 840f7ba
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Showing 2 changed files with 12 additions and 23 deletions.
diff --git a/src/ra_server.erl b/src/ra_server.erl
@@ -919,23 +919,10 @@ handle_candidate(#pre_vote_rpc{term = Term} = Msg,
 handle_candidate(#request_vote_rpc{}, State = #{current_term := Term}) ->
     Reply = #request_vote_result{term = Term, vote_granted = false},
     {candidate, State, [{reply, Reply}]};
-handle_candidate(#pre_vote_rpc{term = Term, last_log_index = PeerLastIdx} = PreVote,
-                 #{current_term := CurTerm,
-                   cfg := #cfg{log_id = LogId}} = State)
-  when Term =:= CurTerm ->
-    %% This clause is necessary to prevent the liveness issue reported in https://github.com/rabbitmq/ra/issues/439
-    {LastIdx, _} = last_idx_term(State),
-    case PeerLastIdx > LastIdx of
-        true ->
-            ?INFO("~ts: candidate pre_vote_rpc with higher last index received ~b -> ~b",
-                  [LogId, LastIdx, PeerLastIdx]),
-            process_pre_vote(candidate, PreVote, State);
-        false ->
-            {candidate, State, []}
-    end;
-handle_candidate(#pre_vote_rpc{}, State) ->
-    %% just ignore pre_votes that aren't of a higher term
-    {candidate, State, []};
+handle_candidate(#pre_vote_rpc{} = PreVote, State) ->
+    %% unlink request_vote_rpc, candidate cannot simply reject pre_vote_rpc that does not have a higher term
+    %% (see https://github.com/rabbitmq/ra/issues/439 for the detail)
+    process_pre_vote(candidate, PreVote, State);
 handle_candidate(#request_vote_result{}, State) ->
     %% handle to avoid logging as unhandled
     {candidate, State, []};

diff --git a/test/ra_server_SUITE.erl b/test/ra_server_SUITE.erl
@@ -1936,18 +1936,20 @@ candidate_receives_pre_vote(_Config) ->
                                token = Token,
                                machine_version = 0,
                                last_log_index = 3, last_log_term = 5},
-    {candidate, #{}, []}
+    % candidate replies `#pre_vote_result{vote_granted=true}` for not lower index
+    {candidate, #{},
+     [{reply, #pre_vote_result{token = Token, vote_granted = true}}]}
         = ra_server:handle_candidate(PreVoteRpc, State),
 
+    % candidate replies `#pre_vote_result{vote_granted=false}` for lower index
+    {candidate, #{},
+     [{reply, #pre_vote_result{token = Token, vote_granted = false}}]}
+        = ra_server:handle_candidate(PreVoteRpc#pre_vote_rpc{last_log_index = 2}, State),
+
     % candidate abdicates for higher term
     {follower, #{current_term := 6}, _}
         = ra_server:handle_candidate(PreVoteRpc#pre_vote_rpc{term = 6}, State),
 
-    % candidate replies `#pre_vote_result{vote_granted=true}` for higher index
-    {candidate, #{},
-     [{reply, #pre_vote_result{token = Token, vote_granted = true}}]}
-        = ra_server:handle_candidate(PreVoteRpc#pre_vote_rpc{last_log_index = 4}, State),
-
     ok.
 
 leader_receives_pre_vote(_Config) ->