correct harmless off-by-one mistake

a gc can only take place if we have at least three files - the current
file (which we cannot gc), the source file and the destination
file. We do a quick check wether there is enough data - garbage or
otherwise - to require more than two files. This can give false
positives since the last message in a file can overrun the
limit, but that's ok as the code that follows performs more accurate
(but also more expensive) checks.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/rabbit_msg_store.erl b/src/rabbit_msg_store.erl
index ed7b55f243..cc1397734a 100644
--- a/src/rabbit_msg_store.erl
+++ b/src/rabbit_msg_store.erl
@@ -1438,8 +1438,8 @@ maybe_compact(State = #msstate { sum_valid_data   = SumValid,
                                  gc_active        = false,
                                  gc_pid           = GCPid,
                                  file_summary_ets = FileSummaryEts })
-  when SumFileSize >= 3 * ?FILE_SIZE_LIMIT andalso
-       (SumFileSize - SumValid) / SumFileSize > ?GARBAGE_FRACTION ->
+  when (SumFileSize > 2 * ?FILE_SIZE_LIMIT andalso
+        (SumFileSize - SumValid) / SumFileSize > ?GARBAGE_FRACTION) ->
     case ets:first(FileSummaryEts) of
         '$end_of_table' ->
             State;