Penciller shutdown when empty

Stop the penciller from writing an empty file, when shutting down and
the L0 Cache is empty.

Also parameter fiddle to see impact of the Penciller changes.

src/leveled_bookie.erl

@@ -157,7 +157,7 @@
 -define(SHUTDOWN_WAITS, 60).
 -define(SHUTDOWN_PAUSE, 10000).
 -define(SNAPSHOT_TIMEOUT, 300000).
--define(JITTER_PROBABILITY, 0.1).
+-define(JITTER_PROBABILITY, 0.01).
 
 -record(state, {inker :: pid(),
                 penciller :: pid(),

src/leveled_penciller.erl

@@ -588,15 +588,18 @@ terminate(Reason, State) ->
                         State
                 end,
     case {UpdState#state.levelzero_pending,
-            get_item(0, State#state.manifest, [])} of
-        {true, []} ->
+            get_item(0, State#state.manifest, []),
+                gb_trees:size(State#state.levelzero_cache)} of
+        {true, [], _} ->
             ok = leveled_sft:sft_close(State#state.levelzero_constructor);
-        {false, []} ->
+        {false, [], 0} ->
+            io:format("Level 0 cache empty at close of Penciller~n");
+        {false, [], _N} ->
             KL = roll_into_list(State#state.levelzero_cache),
             L0Pid = roll_memory(UpdState, KL, true),
             ok = leveled_sft:sft_close(L0Pid);
         _ ->
-            ok
+            io:format("No level zero action on close of Penciller~n")
     end,
     
     leveled_pclerk:rollclerk_close(State#state.roll_clerk),

test/end_to_end/basic_SUITE.erl

@@ -16,7 +16,7 @@ all() -> [
             many_put_fetch_head,
             journal_compaction,
             fetchput_snapshot,
-            load_and_count ,
+            load_and_count,
             load_and_count_withdelete,
             space_clear_ondelete
             ].