Merged bug24810 into default

Author: Emile Joubert

src/rabbit_guid.erl

@@ -19,6 +19,7 @@
 -behaviour(gen_server).
 
 -export([start_link/0]).
+-export([filename/0]).
 -export([gen/0, gen_secure/0, string/2, binary/2]).
 
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
@@ -38,6 +39,7 @@
 -type(guid() :: binary()).
 
 -spec(start_link/0 :: () -> rabbit_types:ok_pid_or_error()).
+-spec(filename/0 :: () -> string()).
 -spec(gen/0 :: () -> guid()).
 -spec(gen_secure/0 :: () -> guid()).
 -spec(string/2 :: (guid(), any()) -> string()).
@@ -51,8 +53,14 @@ start_link() ->
     gen_server:start_link({local, ?SERVER}, ?MODULE,
                           [update_disk_serial()], []).
 
+%% We use this to detect a (possibly rather old) Mnesia directory,
+%% since it has existed since at least 1.7.0 (as far back as I cared
+%% to go).
+filename() ->
+    filename:join(rabbit_mnesia:dir(), ?SERIAL_FILENAME).
+
 update_disk_serial() ->
-    Filename = filename:join(rabbit_mnesia:dir(), ?SERIAL_FILENAME),
+    Filename = filename(),
     Serial = case rabbit_file:read_term_file(Filename) of
                  {ok, [Num]}     -> Num;
                  {error, enoent} -> 0;

src/rabbit_version.erl

@@ -96,7 +96,10 @@ record_desired_for_scope(Scope) ->
 upgrades_required(Scope) ->
     case recorded_for_scope(Scope) of
         {error, enoent} ->
-            {error, version_not_available};
+            case filelib:is_file(rabbit_guid:filename()) of
+                false -> {ok, []}; %% We're blank, no upgrade needed
+                true  -> {error, version_not_available}
+            end;
         {ok, CurrentHeads} ->
             with_upgrade_graph(
               fun (G) ->