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Add a naive diff function

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Mark Allen 2015-10-29 22:18:20 -05:00
parent 7086899941
commit 72a4fab49d
1 changed files with 19 additions and 1 deletions
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20
src/machi_merkle_tree.erl
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@ -102,7 +102,7 @@ filename(#mt{ filename = F }) -> F.
diff(#mt{backend = naive, tree = T1}, #mt{backend = naive, tree = T2}) ->
case T1#naive.root == T2#naive.root of
true -> same;
false -> different %% TODO: implement diff
false -> naive_diff(T1, T2)
end;
diff(#mt{backend = merklet, tree = T1}, #mt{backend = merklet, tree = T2}) ->
case merklet:diff(T1, T2) of
@ -201,3 +201,21 @@ build_level_1(Size, [{Pos, Len, Hash}|T], Multiple, [ Ctx | Rest ])
build_level_1(Size, [{Pos, Len, Hash}|T], Multiple, [ Ctx | Rest ])
when ( Pos + Len ) =< ( Size * Multiple ) ->
build_level_1(Size, T, Multiple, [ crypto:hash_update(Ctx, Hash) | Rest ]).
naive_diff(#naive{lvl1 = L1}, #naive{lvl1=L2, chunk_size=CS2}) ->
lager:debug("naive diff: Our lvl1: ~p~n", [L1]),
lager:debug("naive diff: Their chunk size: ~p, lvl1: ~p~n", [CS2, L2]),
Set1 = gb_sets:from_list(lists:zip(lists:seq(1, length(L1), L1))),
Set2 = gb_sets:from_list(lists:zip(lists:seq(1, length(L2), L2))),
%% The byte ranges in list 2 that do not match in list 1
%%
%% We have to decide what to do now - should we filter the
%% leaf nodes using these ranges and find specific divergence
%% between Tree1 and Tree2?
%%
%% Or should we do something else?
[ {(X-1)*CS2, CS2, SHA} || {X, SHA} <- gb_sets:to_list(gb_sets:subtract(Set1, Set2)) ].