handle the case of the Syncer dying right at the end

which could previously leave the master blocked, waiting for 'next'.
And move the unlinking, which allows us to ensure we don't end up with
stray 'EXIT's.

1 files changed, 20 insertions, 15 deletions

diff --git a/src/rabbit_mirror_queue_sync.erl b/src/rabbit_mirror_queue_sync.erl
index 3a8a68b87e..c654cde50d 100644
--- a/src/rabbit_mirror_queue_sync.erl
+++ b/src/rabbit_mirror_queue_sync.erl
@@ -58,19 +58,13 @@ master_prepare(Ref, Log, SPids) ->
     spawn_link(fun () -> syncer(Ref, Log, MPid, SPids) end).
 
 master_go(Syncer, Ref, Log, BQ, BQS) ->
-    SendArgs = {Syncer, Ref, Log, rabbit_misc:get_parent()},
-    {Acc, BQS1} =
-        BQ:fold(fun (Msg, MsgProps, {I, Last}) ->
-                        master_send(SendArgs, I, Last, Msg, MsgProps)
-                end, {0, erlang:now()}, BQS),
-    receive
-        {next, Ref} -> ok
-    end,
-    Syncer ! {done, Ref},
-    case Acc of
-        {shutdown,  Reason} -> {shutdown,  Reason, BQS1};
-        {sync_died, Reason} -> {sync_died, Reason, BQS1};
-        _                   -> {ok, BQS1}
+    Args = {Syncer, Ref, Log, rabbit_misc:get_parent()},
+    case BQ:fold(fun (Msg, MsgProps, {I, Last}) ->
+                         master_send(Args, I, Last, Msg, MsgProps)
+                 end, {0, erlang:now()}, BQS) of
+        {{shutdown,  Reason}, BQS1} -> {shutdown,  Reason, BQS1};
+        {{sync_died, Reason}, BQS1} -> {sync_died, Reason, BQS1};
+        {_,                   BQS1} -> master_done(Args, BQS1)
     end.
 
 master_send({Syncer, Ref, Log, Parent}, I, Last, Msg, MsgProps) ->
@@ -93,6 +87,18 @@ master_send({Syncer, Ref, Log, Parent}, I, Last, Msg, MsgProps) ->
         {'EXIT', Syncer, Reason} -> {stop, {sync_died, Reason}}
     end.
 
+master_done({Syncer, Ref, _Log, Parent}, BQS) ->
+    receive
+        {next, Ref}              -> unlink(Syncer),
+                                    Syncer ! {done, Ref},
+                                    receive {'EXIT', Syncer, _} -> ok
+                                    after 0 -> ok
+                                    end,
+                                    {ok, BQS};
+        {'EXIT', Parent, Reason} -> {shutdown,  Reason, BQS};
+        {'EXIT', Syncer, Reason} -> {sync_died, Reason, BQS}
+    end.
+
 %% Master
 %% ---------------------------------------------------------------------------
 %% Syncer
@@ -108,8 +114,7 @@ syncer(Ref, Log, MPid, SPids) ->
                                               {S, _} <- SPidsMRefs1]]),
                        SPidsMRefs2 = syncer_loop({Ref, MPid}, SPidsMRefs1),
                        foreach_slave(SPidsMRefs2, Ref, fun sync_send_complete/3)
-    end,
-    unlink(MPid).
+    end.
 
 syncer_loop({Ref, MPid} = Args, SPidsMRefs) ->
     MPid ! {next, Ref},