New branch for bug 21427

1 files changed, 15 insertions, 7 deletions

diff --git a/src/rabbit_guid.erl b/src/rabbit_guid.erl
index 2be00503..f669b9dc 100644
--- a/src/rabbit_guid.erl
+++ b/src/rabbit_guid.erl
@@ -42,6 +42,7 @@
          terminate/2, code_change/3]).
 
 -define(SERVER, ?MODULE).
+-define(SERIAL_FILENAME, "rabbit_guid").
 
 -record(state, {serial}).
 
@@ -59,17 +60,24 @@
 %%----------------------------------------------------------------------------
 
 start_link() ->
-    %% The persister can get heavily loaded, and we don't want that to
-    %% impact guid generation.  We therefore keep the serial in a
-    %% separate process rather than calling rabbit_persister:serial/0
-    %% directly in the functions below.
     gen_server:start_link({local, ?SERVER}, ?MODULE,
-                          [rabbit_persister:serial()], []).
+                          [update_disk_serial()], []).
+
+update_disk_serial() ->
+    Filename = filename:join(mnesia:system_info(directory), ?SERIAL_FILENAME),
+    Serial = case file:read_file(Filename) of
+                 {ok, Content} ->
+                     binary_to_term(Content);
+                 {error, _} ->
+                     rabbit_persister:serial()
+             end,
+    ok = file:write_file(Filename, term_to_binary(Serial + 1)),
+    Serial.
 
 %% generate a guid that is monotonically increasing per process.
 %%
 %% The id is only unique within a single cluster and as long as the
-%% persistent message store hasn't been deleted.
+%% serial store hasn't been deleted.
 guid() ->
     %% We don't use erlang:now() here because a) it may return
     %% duplicates when the system clock has been rewound prior to a
@@ -77,7 +85,7 @@ guid() ->
     %% now() to move ahead of the system time), and b) it is really
     %% slow since it takes a global lock and makes a system call.
     %%
-    %% rabbit_persister:serial/0, in combination with self/0 (which
+    %% A persisted serial number, in combination with self/0 (which
     %% includes the node name) uniquely identifies a process in space
     %% and time. We combine that with a process-local counter to give
     %% us a GUID that is monotonically increasing per process.