Draft of branch to condense range_only keys

This commit is contained in:
martinsumner 2017-03-10 20:43:37 +00:00
parent 730ab2ec48
commit b2f3d882a9
3 changed files with 210 additions and 106 deletions

View file

@ -61,7 +61,8 @@
generate_uuid/0,
integer_now/0,
riak_extract_metadata/2,
magic_hash/1]).
magic_hash/1,
to_lookup/1]).
-define(V1_VERS, 1).
-define(MAGIC, 53). % riak_kv -> riak_object
@ -73,6 +74,14 @@
%% what they are -
%% http://stackoverflow.com/questions/10696223/reason-for-5381-number-in-djb-hash-function
to_lookup(Key) ->
case element(1, Key) of
?IDX_TAG ->
no_lookup;
_ ->
lookup
end.
magic_hash({?RIAK_TAG, Bucket, Key, _SubKey}) ->
magic_hash({Bucket, Key});
magic_hash({?STD_TAG, Bucket, Key, _SubKey}) ->

View file

@ -259,7 +259,7 @@
{error, "False result returned from SST with filename ~s as "
++ "slot ~w has failed crc check"}},
{"SST03",
{info, "Opening SST file with filename ~s keys ~w slots ~w and"
{info, "Opening SST file with filename ~s slots ~w and"
++ " max sqn ~w"}},
{"SST04",
{info, "Exit called for reason ~w on filename ~s"}},

View file

@ -66,6 +66,8 @@
-define(MAX_SLOTS, 256).
-define(SLOT_SIZE, 128). % This is not configurable
-define(NOLOOK_MULT, 2). % How much bigger is a slot/block with no lookups
-define(NOLOOK_SLOTSIZE, ?SLOT_SIZE * ?NOLOOK_MULT).
-define(COMPRESSION_LEVEL, 1).
-define(BINARY_SETTINGS, [{compressed, ?COMPRESSION_LEVEL}]).
% -define(LEVEL_BLOOM_BITS, [{0, 8}, {1, 10}, {2, 8}, {default, 6}]).
@ -143,22 +145,23 @@ sst_open(RootPath, Filename) ->
sst_new(RootPath, Filename, Level, KVList, MaxSQN) ->
{ok, Pid} = gen_fsm:start(?MODULE, [], []),
SlotList = merge_lists(KVList),
case gen_fsm:sync_send_event(Pid,
{sst_new,
RootPath,
Filename,
Level,
KVList,
SlotList,
MaxSQN},
infinity) of
{ok, {SK, EK}} ->
{ok, Pid, {SK, EK}}
end.
sst_new(RootPath, Filename, KL1, KL2, IsBasement, Level, MaxSQN) ->
{{Rem1, Rem2}, MergedList} = merge_lists(KL1, KL2, {IsBasement, Level}),
case MergedList of
[] ->
sst_new(RootPath, Filename, KVL1, KVL2, IsBasement, Level, MaxSQN) ->
{Rem1, Rem2, SlotList} = merge_lists(KVL1, KVL2, {IsBasement, Level}),
case SlotList of
{_, []} ->
empty;
_ ->
{ok, Pid} = gen_fsm:start(?MODULE, [], []),
@ -167,7 +170,7 @@ sst_new(RootPath, Filename, KL1, KL2, IsBasement, Level, MaxSQN) ->
RootPath,
Filename,
Level,
MergedList,
SlotList,
MaxSQN},
infinity) of
{ok, {SK, EK}} ->
@ -241,13 +244,14 @@ starting({sst_open, RootPath, Filename}, _From, State) ->
{ok, {Summary#summary.first_key, Summary#summary.last_key}},
reader,
UpdState};
starting({sst_new, RootPath, Filename, Level, KVList, MaxSQN}, _From, State) ->
starting({sst_new, RootPath, Filename, Level, SlotList, MaxSQN},
_From, State) ->
SW = os:timestamp(),
{FirstKey,
Length,
SlotIndex,
BlockIndex,
SlotsBin} = build_all_slots(KVList),
SlotsBin} = build_all_slots(SlotList),
SummaryBin = build_table_summary(SlotIndex,
Level,
FirstKey,
@ -268,15 +272,16 @@ starting({sst_newlevelzero, RootPath, Filename,
Slots, FetchFun, Penciller, MaxSQN}, State) ->
SW = os:timestamp(),
KVList = leveled_pmem:to_list(Slots, FetchFun),
SlotList = merge_lists(KVList),
{FirstKey,
Length,
SlotCount,
SlotIndex,
BlockIndex,
SlotsBin} = build_all_slots(KVList),
SlotsBin} = build_all_slots(SlotList),
SummaryBin = build_table_summary(SlotIndex,
0,
FirstKey,
Length,
SlotCount,
MaxSQN),
ActualFilename = write_file(RootPath, Filename, SummaryBin, SlotsBin),
UpdState = read_file(ActualFilename, State#state{root_path=RootPath}),
@ -534,14 +539,13 @@ read_file(Filename, State) ->
{Handle, SummaryBin} = open_reader(filename:join(State#state.root_path,
Filename)),
{Summary, SlotList} = read_table_summary(SummaryBin),
SlotCount = length(SlotList),
BlockIndexCache = array:new([{size, SlotCount}, {default, none}]),
BlockIndexCache = array:new([{size, Summary#summary.size},
{default, none}]),
UpdState = State#state{blockindex_cache = BlockIndexCache},
SlotIndex = from_list(SlotList),
UpdSummary = Summary#summary{index = SlotIndex},
leveled_log:log("SST03", [Filename,
Summary#summary.size,
SlotCount,
Summary#summary.max_sqn]),
UpdState#state{summary = UpdSummary,
handle = Handle,
@ -554,13 +558,13 @@ open_reader(Filename) ->
{ok, SummaryBin} = file:pread(Handle, SlotsLength + 8, SummaryLength),
{Handle, SummaryBin}.
build_table_summary(SlotList, _Level, FirstKey, L, MaxSQN) ->
[{LastKey, _LastV}|_Rest] = SlotList,
build_table_summary(SlotIndex, _Level, FirstKey, SlotCount, MaxSQN) ->
[{LastKey, _LastV}|_Rest] = SlotIndex,
Summary = #summary{first_key = FirstKey,
last_key = LastKey,
size = L,
size = SlotCount,
max_sqn = MaxSQN},
SummBin = term_to_binary({Summary, lists:reverse(SlotList)},
SummBin = term_to_binary({Summary, lists:reverse(SlotIndex)},
?BINARY_SETTINGS),
SummCRC = erlang:crc32(SummBin),
<<SummCRC:32/integer, SummBin/binary>>.
@ -574,15 +578,12 @@ read_table_summary(BinWithCheck) ->
binary_to_term(SummBin)
end.
build_all_slots(KVList) ->
L = length(KVList),
% The length is not a constant time command and the list may be large,
% but otherwise length must be called each iteration to avoid exception
% on split or sublist
build_all_slots(SlotList) ->
[{_Lookup, KVList}|_R] = SlotList,
[{FirstKey, _FirstV}|_Rest] = KVList,
SlotCount = L div ?SLOT_SIZE + 1,
BuildResponse = build_all_slots(KVList,
SlotCount,
SlotCount = length(SlotList),
BuildResponse = build_all_slots(SlotList,
8,
1,
[],
@ -590,33 +591,26 @@ build_all_slots(KVList) ->
{default, none}]),
<<>>),
{SlotIndex, BlockIndex, SlotsBin} = BuildResponse,
{FirstKey, L, SlotIndex, BlockIndex, SlotsBin}.
{FirstKey, SlotCount, SlotIndex, BlockIndex, SlotsBin}.
build_all_slots([], _SC, _Pos, _SlotID, SlotIdx, BlockIdxA, SlotsBin) ->
{SlotIdx, BlockIdxA, SlotsBin};
build_all_slots(KVL, SC, Pos, SlotID, SlotIdx, BlockIdxA, SlotsBin) ->
{SlotList, KVRem} =
case SC of
1 ->
{lists:sublist(KVL, ?SLOT_SIZE), []};
_N ->
lists:split(?SLOT_SIZE, KVL)
end,
{LastKey, _V} = lists:last(SlotList),
{BlockIndex, SlotBin, HashList} = generate_binary_slot(SlotList),
build_all_slots([], _Pos, _SlotID, SlotIdxAcc, BlockIdxAcc, SlotBinAcc) ->
{SlotIdxAcc, BlockIdxAcc, SlotBinAcc};
build_all_slots(SlotList, Pos, SlotID, SlotIdxAcc, BlockIdxAcc, SlotBinAcc) ->
[{Lookup, KVList}|Rest] = SlotList,
{LastKey, _LastV} = lists:last(KVList),
{BlockIdx, SlotBin, HashList} = generate_binary_slot(Lookup, KVList),
Length = byte_size(SlotBin),
Bloom = leveled_tinybloom:create_bloom(HashList),
SlotIndexV = #slot_index_value{slot_id = SlotID,
start_position = Pos,
length = Length,
bloom = Bloom},
build_all_slots(KVRem,
SC - 1,
build_all_slots(Rest,
Pos + Length,
SlotID + 1,
[{LastKey, SlotIndexV}|SlotIdx],
array:set(SlotID - 1, BlockIndex, BlockIdxA),
<<SlotsBin/binary, SlotBin/binary>>).
[{LastKey, SlotIndexV}|SlotIdxAcc],
array:set(SlotID - 1, BlockIdx, BlockIdxAcc),
<<SlotBinAcc/binary, SlotBin/binary>>).
generate_filenames(RootFilename) ->
@ -700,7 +694,7 @@ lookup_slots(StartKey, EndKey, Tree) ->
%% based on a 17-bit hash (so 0.0039 fpr).
generate_binary_slot(KVL) ->
generate_binary_slot(Lookup, KVL) ->
HashFoldFun =
fun({K, V}, {PosBinAcc, NoHashCount, HashAcc}) ->
@ -733,49 +727,66 @@ generate_binary_slot(KVL) ->
end
end,
{PosBinIndex0, NHC, HashL} = lists:foldr(HashFoldFun, {<<>>, 0, []}, KVL),
PosBinIndex1 =
case NHC of
0 ->
PosBinIndex0;
_ ->
N = NHC - 1,
<<0:1/integer, N:7/integer, PosBinIndex0/binary>>
{HashL, PosBinIndex} =
case Lookup of
lookup ->
{PosBinIndex0,
NHC,
HashL0} = lists:foldr(HashFoldFun, {<<>>, 0, []}, KVL),
PosBinIndex1 =
case NHC of
0 ->
PosBinIndex0;
_ ->
N = NHC - 1,
<<0:1/integer, N:7/integer, PosBinIndex0/binary>>
end,
{HashL0, PosBinIndex1};
no_lookup ->
{[], <<0:1/integer, 127:7/integer>>}
end,
BlockSize =
case Lookup of
lookup ->
?SLOT_SIZE div 4;
no_lookup ->
?NOLOOK_SLOTSIZE div 4
end,
{B1, B2, B3, B4} =
case length(KVL) of
L when L =< 32 ->
L when L =< BlockSize ->
{term_to_binary(KVL, ?BINARY_SETTINGS),
<<0:0>>,
<<0:0>>,
<<0:0>>};
L when L =< 64 ->
{KVLA_32, KVLB_32} = lists:split(32, KVL),
{term_to_binary(KVLA_32, ?BINARY_SETTINGS),
term_to_binary(KVLB_32, ?BINARY_SETTINGS),
L when L =< 2 * BlockSize ->
{KVLA, KVLB} = lists:split(BlockSize, KVL),
{term_to_binary(KVLA, ?BINARY_SETTINGS),
term_to_binary(KVLB, ?BINARY_SETTINGS),
<<0:0>>,
<<0:0>>};
L when L =< 96 ->
{KVLA_32, KVLB_64} = lists:split(32, KVL),
{KVLB_32, KVLC_32} = lists:split(32, KVLB_64),
{term_to_binary(KVLA_32, ?BINARY_SETTINGS),
term_to_binary(KVLB_32, ?BINARY_SETTINGS),
term_to_binary(KVLC_32, ?BINARY_SETTINGS),
L when L =< 3 * BlockSize ->
{KVLA, KVLB_Rest} = lists:split(BlockSize, KVL),
{KVLB, KVLC} = lists:split(BlockSize, KVLB_Rest),
{term_to_binary(KVLA, ?BINARY_SETTINGS),
term_to_binary(KVLB, ?BINARY_SETTINGS),
term_to_binary(KVLC, ?BINARY_SETTINGS),
<<0:0>>};
L when L =< 128 ->
{KVLA_32, KVLB_96} = lists:split(32, KVL),
{KVLB_32, KVLC_64} = lists:split(32, KVLB_96),
{KVLC_32, KVLD_32} = lists:split(32, KVLC_64),
{term_to_binary(KVLA_32, ?BINARY_SETTINGS),
term_to_binary(KVLB_32, ?BINARY_SETTINGS),
term_to_binary(KVLC_32, ?BINARY_SETTINGS),
term_to_binary(KVLD_32, ?BINARY_SETTINGS)}
L when L =< 4 * BlockSize ->
{KVLA, KVLB_Rest} = lists:split(BlockSize, KVL),
{KVLB, KVLC_Rest} = lists:split(BlockSize, KVLB_Rest),
{KVLC, KVLD} = lists:split(BlockSize, KVLC_Rest),
{term_to_binary(KVLA, ?BINARY_SETTINGS),
term_to_binary(KVLB, ?BINARY_SETTINGS),
term_to_binary(KVLC, ?BINARY_SETTINGS),
term_to_binary(KVLD, ?BINARY_SETTINGS)}
end,
B1P = byte_size(PosBinIndex1),
B1P = byte_size(PosBinIndex),
B1L = byte_size(B1),
B2L = byte_size(B2),
B3L = byte_size(B3),
@ -786,12 +797,12 @@ generate_binary_slot(KVL) ->
B3L:32/integer,
B4L:32/integer>>,
SlotBin = <<Lengths/binary,
PosBinIndex1/binary,
PosBinIndex/binary,
B1/binary, B2/binary, B3/binary, B4/binary>>,
CRC32 = erlang:crc32(SlotBin),
FullBin = <<CRC32:32/integer, SlotBin/binary>>,
{<<Lengths/binary, PosBinIndex1/binary>>, FullBin, HashL}.
{<<Lengths/binary, PosBinIndex/binary>>, FullBin, HashL}.
check_blocks([], _Handle, _Slot, _BlockLengths, _LedgerKey) ->
@ -1078,8 +1089,25 @@ find_pos(<<0:1/integer, NHC:7/integer, T/binary>>, Hash, PosList, Count) ->
%%% Merge Functions
%%%============================================================================
%% functions for merging two KV lists with pointers
%% The source lists are merged into lists of slots before the file is created
%% At Level zero, there will be a single source list - and this will always be
%% split into standard size slots
%%
%% At lower levels there will be two source lists and they will need to be
%% merged to ensure that the best conflicting answer survives and compactable
%% KV pairs are discarded.
%%
%% At lower levels slots can be larger if there are no lookup keys present in
%% the slot. This is to slow the growth of the manifest/number-of-files when
%% large numbers of index keys are present - as well as improving compression
%% ratios in the Ledger.
%%
%% The outcome of merge_lists/1 and merge_lists/3 should be an list of slots.
%% Each slot should be ordered by Key and be of the form {Flag, KVList}, where
%% Flag can either be lookup or no-lookup. The list of slots should also be
%% ordered by Key (i.e. the first key in the slot)
%%
%% For merging ...
%% Compare the keys at the head of the list, and either skip that "best" key or
%% identify as the next key.
%%
@ -1090,23 +1118,82 @@ find_pos(<<0:1/integer, NHC:7/integer, T/binary>>, Hash, PosList, Count) ->
%% there are matching keys then the highest sequence number must be chosen and
%% any lower sequence numbers should be compacted out of existence
merge_lists(KeyList1, KeyList2, LevelInfo) ->
merge_lists(KeyList1, KeyList2, LevelInfo, [], ?MAX_SLOTS * ?SLOT_SIZE).
merge_lists(KVList1) ->
SlotCount = length(KVList1) div ?SLOT_SIZE,
split_lists(KVList1, [], SlotCount).
merge_lists([], [], _LevelR, MergedList, _MaxSize) ->
{{[], []}, lists:reverse(MergedList)};
merge_lists(Rem1, Rem2, _LevelR, MergedList, 0) ->
{{Rem1, Rem2}, lists:reverse(MergedList)};
merge_lists(KeyList1, KeyList2, {IsBasement, TS}, MergedList, MaxSize) ->
case key_dominates(KeyList1, KeyList2, {IsBasement, TS}) of
{{next_key, TopKey}, Rem1, Rem2} ->
merge_lists(Rem1,
split_lists([], SlotLists, 0) ->
lists:reverse(SlotLists);
split_lists(LastPuff, SlotLists, 0) ->
lists:reverse([{lookup, LastPuff}|SlotLists]);
split_lists(KVList1, SlotLists, N) ->
{Slot, KVListRem} = lists:split(?SLOT_SIZE, KVList1),
split_lists(KVListRem, [{lookup, Slot}|SlotLists], N - 1).
merge_lists(KVList1, KVList2, LevelInfo) ->
merge_lists(KVList1, KVList2, LevelInfo, [], 0).
merge_lists(KVList1, KVList2, _LI, SlotList, ?MAX_SLOTS) ->
{KVList1, KVList2, lists:reverse(SlotList)};
merge_lists([], [], _LI, SlotList, _SlotCount) ->
{[], [], lists:reverse(SlotList)};
merge_lists(KVList1, KVList2, LI, SlotList, SlotCount) ->
{KVRem1,
KVRem2,
Slot} = form_slot(KVList1, KVList2, LI, no_lookup, 0, []),
case Slot of
[] ->
merge_lists(KVRem1, KVRem2, LI, SlotList, SlotCount);
_ ->
merge_lists(KVRem1, KVRem2, LI, [Slot|SlotList], SlotCount + 1)
end.
form_slot([], [], _LI, Type, _Size, Slot) ->
{[], [], {Type, lists:reverse(Slot)}};
form_slot(KVList1, KVList2, _LI, lookup, ?SLOT_SIZE, Slot) ->
{KVList1, KVList2, {lookup, lists:reverse(Slot)}};
form_slot(KVList1, KVList2, _LI, no_lookup, ?NOLOOK_SLOTSIZE, Slot) ->
{KVList1, KVList2, {no_lookup, lists:reverse(Slot)}};
form_slot(KVList1, KVList2, {IsBasement, TS}, lookup, Size, Slot) ->
case key_dominates(KVList1, KVList2, {IsBasement, TS}) of
{{next_key, TopKV}, Rem1, Rem2} ->
form_slot(Rem1,
Rem2,
{IsBasement, TS},
[TopKey|MergedList],
MaxSize - 1);
lookup,
Size + 1,
[TopKV|Slot]);
{skipped_key, Rem1, Rem2} ->
merge_lists(Rem1, Rem2, {IsBasement, TS}, MergedList, MaxSize)
form_slot(Rem1, Rem2, {IsBasement, TS}, lookup, Size, Slot)
end;
form_slot(KVList1, KVList2, {IsBasement, TS}, no_lookup, Size, Slot) ->
case key_dominates(KVList1, KVList2, {IsBasement, TS}) of
{{next_key, {TopK, TopV}}, Rem1, Rem2} ->
case leveled_codec:to_lookup(TopK) of
no_lookup ->
form_slot(Rem1,
Rem2,
{IsBasement, TS},
no_lookup,
Size + 1,
[{TopK, TopV}|Slot]);
lookup ->
case Size >= ?SLOT_SIZE of
true ->
{KVList1,
KVList2,
{no_lookup, lists:reverse(Slot)}};
false ->
form_slot(Rem1,
Rem2,
{IsBasement, TS},
lookup,
Size + 1,
[{TopK, TopV}|Slot])
end
end;
{skipped_key, Rem1, Rem2} ->
form_slot(Rem1, Rem2, {IsBasement, TS}, lookup, Size, Slot)
end.
key_dominates(KL1, KL2, Level) ->
@ -1255,7 +1342,7 @@ indexed_list_test() ->
SW0 = os:timestamp(),
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(KVL1),
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(lookup, KVL1),
io:format(user,
"Indexed list created slot in ~w microseconds of size ~w~n",
[timer:now_diff(os:timestamp(), SW0), byte_size(FullBin)]),
@ -1283,7 +1370,7 @@ indexed_list_mixedkeys_test() ->
KVL1 = lists:sublist(KVL0, 33),
Keys = lists:ukeysort(1, generate_indexkeys(60) ++ KVL1),
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(Keys),
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(lookup, Keys),
{TestK1, TestV1} = lists:nth(4, KVL1),
MH1 = leveled_codec:magic_hash(TestK1),
@ -1309,7 +1396,7 @@ indexed_list_mixedkeys2_test() ->
IdxKeys2 = lists:ukeysort(1, generate_indexkeys(30)),
% this isn't actually ordered correctly
Keys = IdxKeys1 ++ KVL1 ++ IdxKeys2,
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(Keys),
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(lookup, Keys),
lists:foreach(fun({K, V}) ->
MH = leveled_codec:magic_hash(K),
test_binary_slot(FullBin, K, MH, {K, V})
@ -1318,7 +1405,7 @@ indexed_list_mixedkeys2_test() ->
indexed_list_allindexkeys_test() ->
Keys = lists:sublist(lists:ukeysort(1, generate_indexkeys(150)), 128),
{PosBinIndex1, FullBin, _HL} = generate_binary_slot(Keys),
{PosBinIndex1, FullBin, _HL} = generate_binary_slot(lookup, Keys),
?assertMatch(<<_BL:20/binary, 127:8/integer>>, PosBinIndex1),
% SW = os:timestamp(),
BinToList = binaryslot_tolist(FullBin),
@ -1328,10 +1415,22 @@ indexed_list_allindexkeys_test() ->
?assertMatch(Keys, BinToList),
?assertMatch(Keys, binaryslot_trimmedlist(FullBin, all, all)).
indexed_list_allindexkeys_nolookup_test() ->
Keys = lists:sublist(lists:ukeysort(1, generate_indexkeys(1000)),
128 * ?NOLOOK_MULT),
{PosBinIndex1, FullBin, _HL} = generate_binary_slot(no_lookup, Keys),
?assertMatch(<<_BL:20/binary, 127:8/integer>>, PosBinIndex1),
% SW = os:timestamp(),
BinToList = binaryslot_tolist(FullBin),
% io:format(user,
% "Indexed list flattened in ~w microseconds ~n",
% [timer:now_diff(os:timestamp(), SW)]),
?assertMatch(Keys, BinToList),
?assertMatch(Keys, binaryslot_trimmedlist(FullBin, all, all)).
indexed_list_allindexkeys_trimmed_test() ->
Keys = lists:sublist(lists:ukeysort(1, generate_indexkeys(150)), 128),
{PosBinIndex1, FullBin, _HL} = generate_binary_slot(Keys),
{PosBinIndex1, FullBin, _HL} = generate_binary_slot(lookup, Keys),
?assertMatch(<<_BL:20/binary, 127:8/integer>>, PosBinIndex1),
?assertMatch(Keys, binaryslot_trimmedlist(FullBin,
{i,
@ -1369,7 +1468,7 @@ indexed_list_mixedkeys_bitflip_test() ->
KVL0 = lists:ukeysort(1, generate_randomkeys(1, 50, 1, 4)),
KVL1 = lists:sublist(KVL0, 33),
Keys = lists:ukeysort(1, generate_indexkeys(60) ++ KVL1),
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(Keys),
{_PosBinIndex1, FullBin, _HL} = generate_binary_slot(lookup, Keys),
L = byte_size(FullBin),
Byte1 = random:uniform(L),
<<PreB1:Byte1/binary, A:8/integer, PostByte1/binary>> = FullBin,
@ -1423,16 +1522,12 @@ merge_test() ->
?assertMatch(ExpLK2, LK2),
ML1 = [{next, #manifest_entry{owner = P1}, FK1}],
ML2 = [{next, #manifest_entry{owner = P2}, FK2}],
{ok, P3, {{Rem1, Rem2}, FK3, LK3}} = sst_new("../test/",
"level2_merge",
ML1,
ML2,
false,
2,
N * 2),
NewR = sst_new("../test/", "level2_merge", ML1, ML2, false, 2, N * 2),
{ok, P3, {{Rem1, Rem2}, FK3, LK3}} = NewR,
?assertMatch([], Rem1),
?assertMatch([], Rem2),
?assertMatch(true, FK3 == min(FK1, FK2)),
io:format("LK1 ~w LK2 ~w LK3 ~w~n", [LK1, LK2, LK3]),
?assertMatch(true, LK3 == max(LK1, LK2)),
io:format(user,
"Created and merged two files of size ~w in ~w microseconds~n",