dq: revert the table change to earlier on, so that recovery isn't as horrendously slow. amqq_proc: correct order of actions in delete_queue and document.

2 files changed, 19 insertions, 11 deletions

diff --git a/src/rabbit_amqqueue_process.erl b/src/rabbit_amqqueue_process.erl
index 9d97e881ac..45f311f752 100644
--- a/src/rabbit_amqqueue_process.erl
+++ b/src/rabbit_amqqueue_process.erl
@@ -122,8 +122,14 @@ terminate(_Reason, State) ->
     %% FIXME: How do we cancel active subscriptions?
     State1 = stop_memory_timer(State),
     QName = qname(State1),
-    ok = rabbit_amqqueue:internal_delete(QName),
-    {ok, _MS} = rabbit_mixed_queue:delete_queue(State1 #q.mixed_state).
+    %% Delete from disk queue first. If we crash at this point, when a
+    %% durable queue, we will be recreated at startup, possibly with
+    %% partial content. The alternative is much worse however - if we
+    %% called internal_delete first, we would then have a race between
+    %% the disk_queue delete and a new queue with the same name being
+    %% created and published to.
+    {ok, _MS} = rabbit_mixed_queue:delete_queue(State1 #q.mixed_state),
+    ok = rabbit_amqqueue:internal_delete(QName).
 
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
diff --git a/src/rabbit_disk_queue.erl b/src/rabbit_disk_queue.erl
index 0ff4c50e73..28e74537bf 100644
--- a/src/rabbit_disk_queue.erl
+++ b/src/rabbit_disk_queue.erl
@@ -381,6 +381,17 @@ init([FileSizeLimit, ReadFileHandlesLimit]) ->
     ok = rabbit_memory_manager:register
            (self(), true, rabbit_disk_queue, set_mode, []),
     ok = filelib:ensure_dir(form_filename("nothing")),
+
+    Node = node(),
+    ok = 
+        case mnesia:change_table_copy_type(rabbit_disk_queue, Node,
+                                           disc_copies) of
+            {atomic, ok} -> ok;
+            {aborted, {already_exists, rabbit_disk_queue, Node,
+                       disc_copies}} -> ok;
+            E -> E
+        end,
+
     file:delete(form_filename(atom_to_list(?MSG_LOC_NAME) ++
                               ?FILE_EXTENSION_DETS)),
     {ok, MsgLocationDets} =
@@ -429,15 +440,6 @@ init([FileSizeLimit, ReadFileHandlesLimit]) ->
     {ok, State1 = #dqstate { current_file_name = CurrentName,
                              current_offset = Offset } } =
         load_from_disk(State),
-    Node = node(),
-    ok = 
-        case mnesia:change_table_copy_type(rabbit_disk_queue, Node,
-                                           disc_copies) of
-            {atomic, ok} -> ok;
-            {aborted, {already_exists, rabbit_disk_queue, Node,
-                       disc_copies}} -> ok;
-            E -> E
-        end,
     %% read is only needed so that we can seek
     {ok, FileHdl} = file:open(form_filename(CurrentName),
                               [read, write, raw, binary, delayed_write]),