From e01b310d2059fd77e6d357fdcd415661ee3b329f Mon Sep 17 00:00:00 2001
From: martinsumner <martin.sumner@adaptip.co.uk>
Date: Thu, 29 Dec 2016 05:09:47 +0000
Subject: [PATCH] Handle production of empty file

---
 src/leveled_log.erl    |  2 --
 src/leveled_pclerk.erl |  4 +---
 src/leveled_sst.erl    | 25 +++++++++++++++----------
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/leveled_log.erl b/src/leveled_log.erl
index 8ab798f..de73c23 100644
--- a/src/leveled_log.erl
+++ b/src/leveled_log.erl
@@ -152,8 +152,6 @@
         {info, "File to be created as part of MSN=~w Filename=~s"}},
     {"PC013",
         {warn, "Merge resulted in empty file ~s"}},
-    {"PC014",
-        {info, "Empty file ~s to be cleared"}},
     {"PC015",
         {info, "File created"}},
     {"PC016",
diff --git a/src/leveled_pclerk.erl b/src/leveled_pclerk.erl
index 2f29920..1744a3d 100644
--- a/src/leveled_pclerk.erl
+++ b/src/leveled_pclerk.erl
@@ -319,10 +319,8 @@ do_merge(KL1, KL2, {SrcLevel, IsB}, {Filepath, MSN}, MaxSQN,
                                             SrcLevel + 1,
                                             MaxSQN),
     case Reply of
-        {{[], []}, null, _} ->
+        empty ->
             leveled_log:log("PC013", [FileName]),
-            leveled_log:log("PC014", [FileName]),
-            ok = leveled_sst:sst_clear(Pid),
             OutList;                        
         {{KL1Rem, KL2Rem}, SmallestKey, HighestKey} ->
             ExtMan = lists:append(OutList,
diff --git a/src/leveled_sst.erl b/src/leveled_sst.erl
index 3fc5ef3..41fcbb6 100644
--- a/src/leveled_sst.erl
+++ b/src/leveled_sst.erl
@@ -146,16 +146,21 @@ sst_new(Filename, Level, KVList, MaxSQN) ->
 
 sst_new(Filename, KL1, KL2, IsBasement, Level, MaxSQN) ->
     {{Rem1, Rem2}, MergedList} = merge_lists(KL1, KL2, {IsBasement, Level}),
-    {ok, Pid} = gen_fsm:start(?MODULE, [], []),
-    case gen_fsm:sync_send_event(Pid,
-                                    {sst_new,
-                                        Filename,
-                                        Level,
-                                        MergedList,
-                                        MaxSQN},
-                                    infinity) of
-        {ok, {SK, EK}} ->
-            {ok, Pid, {{Rem1, Rem2}, SK, EK}}
+    case MergedList of
+        [] ->
+            empty;
+        _ ->
+            {ok, Pid} = gen_fsm:start(?MODULE, [], []),
+            case gen_fsm:sync_send_event(Pid,
+                                            {sst_new,
+                                                Filename,
+                                                Level,
+                                                MergedList,
+                                                MaxSQN},
+                                            infinity) of
+                {ok, {SK, EK}} ->
+                    {ok, Pid, {{Rem1, Rem2}, SK, EK}}
+            end
     end.
 
 sst_newlevelzero(Filename, Slots, FetchFun, Penciller, MaxSQN) ->