remove unused state var

We were diligently maintaining ack_msg_id, but never actually using it
for anything. And it's always been like that.

1 files changed, 14 insertions, 29 deletions

diff --git a/src/rabbit_mirror_queue_master.erl b/src/rabbit_mirror_queue_master.erl
index c8a361b1..009971bb 100644
--- a/src/rabbit_mirror_queue_master.erl
+++ b/src/rabbit_mirror_queue_master.erl
@@ -40,7 +40,6 @@
                  backing_queue_state,
                  seen_status,
                  confirmed,
-                 ack_msg_id,
                  known_senders
                }).
 
@@ -56,7 +55,6 @@
                                  backing_queue_state :: any(),
                                  seen_status         :: dict(),
                                  confirmed           :: [rabbit_guid:guid()],
-                                 ack_msg_id          :: dict(),
                                  known_senders       :: set()
                                }).
 
@@ -114,7 +112,6 @@ init_with_existing_bq(Q = #amqqueue{name = QName}, BQ, BQS) ->
              backing_queue_state = BQS,
              seen_status         = dict:new(),
              confirmed           = [],
-             ack_msg_id          = dict:new(),
              known_senders       = sets:new() }.
 
 stop_mirroring(State = #state { coordinator         = CPid,
@@ -187,13 +184,11 @@ publish_delivered(Msg = #basic_message { id = MsgId }, MsgProps,
                   ChPid, State = #state { gm                  = GM,
                                           seen_status         = SS,
                                           backing_queue       = BQ,
-                                          backing_queue_state = BQS,
-                                          ack_msg_id          = AM }) ->
+                                          backing_queue_state = BQS }) ->
     false = dict:is_key(MsgId, SS), %% ASSERTION
     ok = gm:broadcast(GM, {publish_delivered, ChPid, MsgProps, Msg}),
     {AckTag, BQS1} = BQ:publish_delivered(Msg, MsgProps, ChPid, BQS),
-    AM1 = maybe_store_acktag(AckTag, MsgId, AM),
-    State1 = State #state { backing_queue_state = BQS1, ack_msg_id = AM1 },
+    State1 = State #state { backing_queue_state = BQS1 },
     {AckTag, ensure_monitoring(ChPid, State1)}.
 
 discard(MsgId, ChPid, State = #state { gm                  = GM,
@@ -264,34 +259,29 @@ fetch(AckRequired, State = #state { backing_queue       = BQ,
                                     backing_queue_state = BQS }) ->
     {Result, BQS1} = BQ:fetch(AckRequired, BQS),
     State1 = State #state { backing_queue_state = BQS1 },
-    case Result of
-        empty ->
-            {Result, State1};
-        {#basic_message{id = MsgId}, _IsDelivered, AckTag} ->
-            {Result, drop(MsgId, AckTag, State1)}
-    end.
+    {Result, case Result of
+                 empty                          -> State1;
+                 {_MsgId, _IsDelivered, AckTag} -> drop_one(AckTag, State1)
+             end}.
 
 drop(AckRequired, State = #state { backing_queue       = BQ,
                                    backing_queue_state = BQS }) ->
     {Result, BQS1} = BQ:drop(AckRequired, BQS),
     State1 = State #state { backing_queue_state = BQS1 },
     {Result, case Result of
-                 empty           -> State1;
-                 {MsgId, AckTag} -> drop(MsgId, AckTag, State1)
+                 empty            -> State1;
+                 {_MsgId, AckTag} -> drop_one(AckTag, State1)
              end}.
 
 ack(AckTags, State = #state { gm                  = GM,
                               backing_queue       = BQ,
-                              backing_queue_state = BQS,
-                              ack_msg_id          = AM }) ->
+                              backing_queue_state = BQS }) ->
     {MsgIds, BQS1} = BQ:ack(AckTags, BQS),
     case MsgIds of
         [] -> ok;
         _  -> ok = gm:broadcast(GM, {ack, MsgIds})
     end,
-    AM1 = lists:foldl(fun dict:erase/2, AM, AckTags),
-    {MsgIds, State #state { backing_queue_state = BQS1,
-                            ack_msg_id          = AM1 }}.
+    {MsgIds, State #state { backing_queue_state = BQS1 }}.
 
 foreach_ack(MsgFun, State = #state { backing_queue       = BQ,
                                      backing_queue_state = BQS }, AckTags) ->
@@ -408,7 +398,6 @@ promote_backing_queue_state(CPid, BQ, BQS, GM, AckTags, SeenStatus, KS) ->
              backing_queue_state = BQS1,
              seen_status         = SeenStatus,
              confirmed           = [],
-             ack_msg_id          = dict:new(),
              known_senders       = sets:from_list(KS) }.
 
 sender_death_fun() ->
@@ -440,15 +429,11 @@ depth_fun() ->
 %% Helpers
 %% ---------------------------------------------------------------------------
 
-drop(MsgId, AckTag, State = #state { ack_msg_id          = AM,
-                                     gm                  = GM,
-                                     backing_queue       = BQ,
-                                     backing_queue_state = BQS }) ->
+drop_one(AckTag, State = #state { gm                  = GM,
+                                  backing_queue       = BQ,
+                                  backing_queue_state = BQS }) ->
     ok = gm:broadcast(GM, {drop, BQ:len(BQS), 1, AckTag =/= undefined}),
-    State #state { ack_msg_id = maybe_store_acktag(AckTag, MsgId, AM) }.
-
-maybe_store_acktag(undefined, _MsgId, AM) -> AM;
-maybe_store_acktag(AckTag,     MsgId, AM) -> dict:store(AckTag, MsgId, AM).
+    State.
 
 ensure_monitoring(ChPid, State = #state { coordinator = CPid,
                                           known_senders = KS }) ->