Fix snapshot bug in rabbit_fifo

The waiting_consumers were not being "dehydrated" causing snapshots to
potentially contain message bodies causing occasional test failures in
the snapshots property tests.

2 files changed, 31 insertions, 5 deletions

diff --git a/src/rabbit_fifo.erl b/src/rabbit_fifo.erl
index 97e5f6e901..e551834490 100644
--- a/src/rabbit_fifo.erl
+++ b/src/rabbit_fifo.erl
@@ -1408,7 +1408,8 @@ maybe_queue_consumer(ConsumerId, #consumer{credit = Credit},
 dehydrate_state(#?MODULE{messages = Messages,
                          consumers = Consumers,
                          returns = Returns,
-                         prefix_msgs = {PrefRet0, PrefMsg0}} = State) ->
+                         prefix_msgs = {PrefRet0, PrefMsg0},
+                         waiting_consumers = Waiting0} = State) ->
     %% TODO: optimise this function as far as possible
     PrefRet = lists:foldl(fun ({'$prefix_msg', Header}, Acc) ->
                                   [Header | Acc];
@@ -1422,6 +1423,7 @@ dehydrate_state(#?MODULE{messages = Messages,
                            end,
                            lists:reverse(PrefMsg0),
                            lists:sort(maps:to_list(Messages))),
+    Waiting = [{Cid, dehydrate_consumer(C)} || {Cid, C} <- Waiting0],
     State#?MODULE{messages = #{},
                   ra_indexes = rabbit_fifo_index:empty(),
                   release_cursors = lqueue:new(),
@@ -1431,7 +1433,8 @@ dehydrate_state(#?MODULE{messages = Messages,
                                        end, Consumers),
                   returns = lqueue:new(),
                   prefix_msgs = {lists:reverse(PrefRet),
-                                 lists:reverse(PrefMsgs)}}.
+                                 lists:reverse(PrefMsgs)},
+                  waiting_consumers = Waiting}.
 
 dehydrate_consumer(#consumer{checked_out = Checked0} = Con) ->
     Checked = maps:map(fun (_, {'$prefix_msg', _} = M) ->
diff --git a/test/rabbit_fifo_prop_SUITE.erl b/test/rabbit_fifo_prop_SUITE.erl
index 4ce34c8a13..76b8d7e715 100644
--- a/test/rabbit_fifo_prop_SUITE.erl
+++ b/test/rabbit_fifo_prop_SUITE.erl
@@ -37,7 +37,8 @@ all_tests() ->
      scenario13,
      scenario14,
      scenario15,
-     scenario16
+     scenario16,
+     scenario17
     ].
 
 groups() ->
@@ -270,6 +271,27 @@ scenario16(_Config) ->
                         delivery_limit => 1}, Commands),
     ok.
 
+scenario17(_Config) ->
+    C1Pid = test_util:fake_pid(rabbit@fake_node1),
+    C1 = {<<0>>, C1Pid},
+    % C2Pid = test_util:fake_pid(fake_node1),
+    C2 = {<<>>, C1Pid},
+    E = test_util:fake_pid(rabbit@fake_node2),
+    Commands = [
+                make_checkout(C1, {auto,1,simple_prefetch}),
+                make_enqueue(E,1,<<"one">>),
+                make_checkout(C2, {auto,1,simple_prefetch}),
+                {down, C1Pid, noconnection},
+                make_checkout(C2, cancel),
+                make_enqueue(E,2,<<"two">>),
+                {nodeup,rabbit@fake_node1},
+                make_settle(C1, [0]),
+                make_settle(C1, [1])
+                ],
+    run_snapshot_test(#{name => ?FUNCTION_NAME,
+                        single_active_consumer_on => true
+                       }, Commands),
+    ok.
 
 snapshots(_Config) ->
     run_proper(
@@ -541,8 +563,9 @@ run_snapshot_test0(Conf, Commands) ->
              State -> ok;
              _ ->
                  ct:pal("Snapshot tests failed run log:~n"
-                        "~p~n from ~n~p~n Entries~n~p~n",
-                        [Filtered, SnapState, Entries]),
+                        "~p~n from ~n~p~n Entries~n~p~n"
+                        "Config: ~p~n",
+                        [Filtered, SnapState, Entries, Conf]),
                  ct:pal("Expected~n~p~nGot:~n~p", [State, S]),
                  ?assertEqual(State, S)
          end