minor refactoring

Author: kjnilsson

src/ra_log_segment_writer.erl

@@ -218,7 +218,7 @@ handle_cast({truncate_segments, Who, {Name, _Range} = SegRef},
                             ?DEBUG("segment_writer in '~w': ~s for ~s took ~bms",
                                    [System, ?FUNCTION_NAME, Who, Diff]),
                             case open_successor_segment(Seg, SegConf) of
-                                undefined ->
+                                enoent ->
                                     %% directory must have been deleted after the pivot
                                     %% segment was opened
                                     {noreply, State0};
@@ -450,7 +450,7 @@ append_to_segment(UId, Tid, {Idx, SeqIter} = Cur, Seg0, Closed, State) ->
                 {error, full} ->
                     % close and open a new segment
                     case open_successor_segment(Seg0, State#state.segment_conf) of
-                        undefined ->
+                        enoent ->
                             %% a successor cannot be opened - this is most likely due
                             %% to the directory having been deleted.
                             undefined;
@@ -505,7 +505,7 @@ open_successor_segment(CurSeg, SegConf) ->
         {error, enoent} ->
             %% the directory has been deleted whilst segments were being
             %% written
-            undefined;
+            enoent;
         {ok, Seg} ->
             Seg
     end.
@@ -522,7 +522,13 @@ open_file(Dir, SegConf) ->
     %% existing which could happen after server deletion
     case ra_log_segment:open(File, SegConf#{mode => append}) of
         {ok, Segment} ->
-            Segment;
+            case ra_log_segment:segref(Segment) of
+                undefined ->
+                    Segment;
+                _ ->
+                    %% has entries, open successor
+                    open_successor_segment(Segment, SegConf)
+            end;
         {error, missing_segment_header} ->
             %% a file was created by the segment header had not been
             %% synced. In this case it is typically safe to just delete

src/ra_server.erl

@@ -2320,7 +2320,7 @@ promote_checkpoint(Index, #{log := Log0} = State) ->
 -spec persist_last_applied(ra_server_state()) -> ra_server_state().
 persist_last_applied(#{persisted_last_applied := PLA,
                        last_applied := LA} = State) when LA =< PLA ->
-    % if last applied is less than PL for some reason do nothing
+    % if last applied is less than or equal to PL do nothing
     State;
 persist_last_applied(#{last_applied := LastApplied,
                        cfg := #cfg{uid = UId} = Cfg} = State) ->
@@ -2881,7 +2881,6 @@ apply_to(ApplyTo, ApplyFun, Notifys0, Effects0,
                             erlang:system_time(millisecond) - LastTs
                     end,
     %% due to machine versioning all entries may not have been applied
-    %%
     FinalEffs = make_notify_effects(Notifys, lists:reverse(Effects)),
     put_counter(Cfg, ?C_RA_SVR_METRIC_LAST_APPLIED, AppliedTo),
     put_counter(Cfg, ?C_RA_SVR_METRIC_COMMIT_LATENCY, CommitLatency),