Investigate performance regression

Performance has regressed following the hashtable change.  Speculation
that the hashtable format might not be right, and so there is more
cycling around the hashtree.  Logging added.

src/leveled_cdb.erl

@@ -1092,9 +1092,14 @@ read_integerpairs(<<Int1:32, Int2:32, Rest/binary>>, Pairs) ->
 %% false - don't check the CRC before returning key & value
 %% loose_presence - confirm that the hash of the key is present
 
-search_hash_table(_Handle, [], _Hash, _Key, _QuickCheck) -> 
+search_hash_table(Handle, Entries, Hash, Key, QuickCheck) ->
+    search_hash_table(Handle, Entries, Hash, Key, QuickCheck, 0).
+
+search_hash_table(_Handle, [], _Hash, _Key, _QuickCheck, CycleCount) -> 
+    log_cyclecount(CycleCount),
     missing;
-search_hash_table(Handle, [Entry|RestOfEntries], Hash, Key, QuickCheck) ->
+search_hash_table(Handle, [Entry|RestOfEntries], Hash, Key,
+                                                    QuickCheck, CycleCount) ->
     {ok, _} = file:position(Handle, Entry),
     {StoredHash, DataLoc} = read_next_2_integers(Handle),
     case StoredHash of
@@ -1111,15 +1116,26 @@ search_hash_table(Handle, [Entry|RestOfEntries], Hash, Key, QuickCheck) ->
                                         RestOfEntries,
                                         Hash,
                                         Key,
-                                        QuickCheck);
+                                        QuickCheck,
+                                        CycleCount + 1);
                 _ ->
+                    log_cyclecount(CycleCount),
                     KV 
             end;
         %0 ->
         %    % Hash is 0 so key must be missing as 0 found before Hash matched
         %    missing;
         _ ->
-            search_hash_table(Handle, RestOfEntries, Hash, Key, QuickCheck)
+            search_hash_table(Handle, RestOfEntries, Hash, Key,
+                                                    QuickCheck, CycleCount + 1)
+    end.
+
+log_cyclecount(CycleCount) ->
+    if
+        CycleCount > 8 ->
+            leveled_log:log("CDB15", [CycleCount]);
+        true ->
+            ok
     end.
 
 % Write Key and Value tuples into the CDB.  Each tuple consists of a

src/leveled_log.erl

@@ -260,9 +260,10 @@
     {"CDB13",
         {info, "Write options of ~w"}},
     {"CDB14",
-        {info, "Microsecond imings for hashtree build of "
+        {info, "Microsecond timings for hashtree build of "
-                ++ "to_list ~w sort ~w build ~w"}}
+                ++ "to_list ~w sort ~w build ~w"}},
-    
+    {"CDB15",
+        {info, "Cycle count of ~w in hashtable search higher than expected~n"}}
         ])).