refactor: simplify 'fetch'

1 files changed, 17 insertions, 34 deletions

diff --git a/src/rabbit_variable_queue.erl b/src/rabbit_variable_queue.erl
index 6efe07bac0..f8ced680f5 100644
--- a/src/rabbit_variable_queue.erl
+++ b/src/rabbit_variable_queue.erl
@@ -470,48 +470,31 @@ fetch(AckRequired, State = #vqstate { q4               = Q4,
                    msg_on_disk = MsgOnDisk, index_on_disk = IndexOnDisk }},
          Q4a} ->
 
-            AckTag = case AckRequired of
-                         true  -> SeqId;
-                         false -> blank_ack
-                     end,
-
             %% 1. Mark it delivered if necessary
             IndexState1 = maybe_write_delivered(
                             IndexOnDisk andalso not IsDelivered,
                             SeqId, IndexState),
 
-            %% 2. If it's on disk and there's no Ack required, remove it
+            %% 2. Remove from msg_store and queue index, if necessary
             MsgStore = find_msg_store(IsPersistent),
+            Rem = fun () -> ok = rabbit_msg_store:remove(MsgStore, [Guid]) end,
+            Ack = fun () -> rabbit_queue_index:ack([SeqId], IndexState1) end,
             IndexState2 =
-                case MsgOnDisk andalso not AckRequired of
-                    %% Remove from disk now
-                    true  -> ok = case MsgOnDisk of
-                                      true  -> rabbit_msg_store:remove(
-                                                 MsgStore, [Guid]);
-                                      false -> ok
-                                  end,
-                             case IndexOnDisk of
-                                 true  -> rabbit_queue_index:ack(
-                                            [SeqId], IndexState1);
-                                 false -> IndexState1
-                             end;
-                    false -> IndexState1
-                end,
-
-            %% 3. If it's on disk, not persistent and an ack's
-            %% required then remove it from the queue index only.
-            IndexState3 =
-                case IndexOnDisk andalso AckRequired andalso not IsPersistent of
-                    true  -> rabbit_queue_index:ack([SeqId], IndexState2);
-                    false -> IndexState2
+                case {MsgOnDisk, IndexOnDisk, AckRequired, IsPersistent} of
+                    {true, false, false,     _} -> Rem(), IndexState1;
+                    {true,  true, false,     _} -> Rem(), Ack();
+                    {true,  true,  true, false} -> Ack();
+                    _                           -> IndexState1
                 end,
 
-            %% 4. If an ack is required, add something sensible to PA
-            PA1 = case AckRequired of
-                      true  -> record_pending_ack(MsgStatus #msg_status {
-                                                    is_delivered = true }, PA);
-                      false -> PA
-                  end,
+            %% 3. If an ack is required, add something sensible to PA
+            {AckTag, PA1} = case AckRequired of
+                                true  -> PA2 = record_pending_ack(
+                                                 MsgStatus #msg_status {
+                                                   is_delivered = true }, PA),
+                                         {SeqId, PA2};
+                                false -> {blank_ack, PA}
+                            end,
 
             PCount1 = maybe_dec(PCount, IsPersistent andalso not AckRequired),
             Len1 = Len - 1,
@@ -519,7 +502,7 @@ fetch(AckRequired, State = #vqstate { q4               = Q4,
              State #vqstate { q4               = Q4a,
                               ram_msg_count    = RamMsgCount - 1,
                               out_counter      = OutCount + 1,
-                              index_state      = IndexState3,
+                              index_state      = IndexState2,
                               len              = Len1,
                               persistent_count = PCount1,
                               pending_ack      = PA1 }}