From 5b4c903d53a46e2ed859dbefa329347f5ba6a3cc Mon Sep 17 00:00:00 2001
From: martinsumner <martin.sumner@adaptip.co.uk>
Date: Mon, 2 Jan 2017 20:02:49 +0000
Subject: [PATCH] Check before update on bloom

---
 src/leveled_sst.erl       |  2 +-
 src/leveled_tinybloom.erl | 21 +++++++++++++++++----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/leveled_sst.erl b/src/leveled_sst.erl
index f7903f7..addabe5 100644
--- a/src/leveled_sst.erl
+++ b/src/leveled_sst.erl
@@ -72,7 +72,7 @@
 -define(SLOT_SIZE, 128). % This is not configurable
 -define(COMPRESSION_LEVEL, 1).
 -define(BINARY_SETTINGS, [{compressed, ?COMPRESSION_LEVEL}]).
--define(LEVEL_BLOOM_BITS, [{0, 12}, {1, 10}, {2, 8}, {default, 6}]).
+-define(LEVEL_BLOOM_BITS, [{0, 8}, {1, 10}, {2, 8}, {default, 6}]).
 -define(MERGE_SCANWIDTH, 16).
 -define(DISCARD_EXT, ".discarded").
 -define(DELETE_TIMEOUT, 10000).
diff --git a/src/leveled_tinybloom.erl b/src/leveled_tinybloom.erl
index 73982e5..9d85b9a 100644
--- a/src/leveled_tinybloom.erl
+++ b/src/leveled_tinybloom.erl
@@ -51,6 +51,7 @@ enter(Key, Bloom) ->
     Hash = leveled_codec:magic_hash(Key),
     enter({hash, Hash}, Bloom).
 
+
 check({hash, Hash}, Bloom) ->
     {Slot0, Q, Bit1, Bit2, Bit3} = split_hash(Hash),
     Slot = Slot0 rem dict:size(Bloom),
@@ -83,16 +84,23 @@ check(Key, Bloom) ->
 %%%============================================================================
 
 split_hash(Hash) ->
+    Slot = split_for_slot(Hash),
+    {Q1, H1, H2, H3} = split_for_bits(Hash),
+    {Slot, Q1, H1, H2, H3}.
+
+split_for_slot(Hash) ->
     SlotH1 = Hash band 255,
     SlotH2 = (Hash bsr 8) band 255,
     SlotH3 = (Hash bsr 16) band 255,
     SlotH4 = (Hash bsr 24) band 255,
-    Slot = (SlotH1 bxor SlotH2) bxor (SlotH3 bxor SlotH4),
+    (SlotH1 bxor SlotH2) bxor (SlotH3 bxor SlotH4).
+
+split_for_bits(Hash) ->
     Q1 = Hash band 3,
     H1 = (Hash bsr 2) band 1023,
     H2 = (Hash bsr 12) band 1023,
     H3 = (Hash bsr 22) band 1023,
-    {Slot, Q1, H1, H2, H3}.
+    {Q1, H1, H2, H3}.
 
 split_array(Bin, Q) ->
     case Q of
@@ -113,9 +121,14 @@ split_array(Bin, Q) ->
 add_to_array(Bit, BitArray, ArrayLength) ->
     RestLen = ArrayLength - Bit - 1,
     <<Head:Bit/bitstring,
-        _B:1/bitstring,
+        B:1/integer,
         Rest:RestLen/bitstring>> = BitArray,
-    <<Head/bitstring, 1:1, Rest/bitstring>>.
+    case B of
+        0 ->
+            <<Head/bitstring, 1:1, Rest/bitstring>>;
+        1 ->
+            BitArray
+    end.
 
 getbit(Bit, BitArray, ArrayLength) ->
     RestLen = ArrayLength - Bit - 1,