diff --git a/src/hanoidb_bloom.erl b/src/hanoidb_bloom.erl index 99e3958..52d9991 100644 --- a/src/hanoidb_bloom.erl +++ b/src/hanoidb_bloom.erl @@ -71,7 +71,10 @@ bloom(N, E) when is_number(N), N >= 0, bloom(bits, 32, E). bloom(Mode, N, E) -> - K = 1 + trunc(log2(1/E)), + K = case Mode of + size -> 1 + trunc(log2(1/E)); + bits -> 1 + end, P = pow(E, 1 / K), Mb = @@ -84,7 +87,7 @@ bloom(Mode, N, E) -> M = 1 bsl Mb, D = trunc(log(1-P) / log(1-1/M)), #bloom{e=E, n=D, mb=Mb, size = 0, - a = [bitarray_new(1 bsl Mb) || _ <- lists:seq(1, K)]}. + a = [bitmask_new(Mb) || _ <- lists:seq(1, K)]}. log2(X) -> log(X) / log(2). @@ -145,7 +148,7 @@ masked_pair(Mask, X, Y) -> {X band Mask, Y band Mask}. all_set(_Mask, _I1, _I, []) -> true; all_set(Mask, I1, I, [H|T]) -> - case bitarray_get(I, H) of + case bitmask_get(I, H) of true -> all_set(Mask, I1, (I+I1) band Mask, T); false -> false end. @@ -179,8 +182,44 @@ hash_add(Hashes, #bloom{mb=Mb, a=A, size=Size} = B) -> set_bits(_Mask, _I1, _I, [], Acc) -> lists:reverse(Acc); set_bits(Mask, I1, I, [H|T], Acc) -> - set_bits(Mask, I1, (I+I1) band Mask, T, [bitarray_set(I, H) | Acc]). + set_bits(Mask, I1, (I+I1) band Mask, T, [bitmask_set(I, H) | Acc]). + +%%%========== Dispatch to appropriate representation: +bitmask_new(LogN) -> + if LogN >= 20 -> % Use sparse representation. + hanoidb_sparse_bitmap:new(LogN); + true -> % Use dense representation. + hanoidb_dense_bitmap:new(1 bsl LogN) + end. + +bitmask_set(I, BM) -> + case element(1,BM) of + array -> bitarray_set(I, BM); + sparse_bitmap -> hanoidb_sparse_bitmap:set(I, BM); + dense_bitmap_ets -> hanoidb_dense_bitmap:set(I, BM); + dense_bitmap -> + %% Surprise - we need to mutate a built representation: + hanoidb_dense_bitmap:set(I, hanoidb_dense_bitmap:unbuild(BM)) + end. + +%%% Convert to external form. +bitmask_build(BM) -> + case element(1,BM) of + array -> BM; + sparse_bitmap -> BM; + dense_bitmap_ets -> hanoidb_dense_bitmap:build(BM) + end. + +bitmask_get(I, BM) -> + case element(1,BM) of + array -> bitarray_get(I, BM); + sparse_bitmap -> hanoidb_sparse_bitmap:member(I, BM); + dense_bitmap_ets -> hanoidb_dense_bitmap:member(I, BM); + dense_bitmap -> hanoidb_dense_bitmap:member(I, BM) + end. + +%%%========== Bitarray representation - suitable for sparse arrays ========== bitarray_new(N) -> array:new((N-1) div ?W + 1, {default, 0}). -spec bitarray_set( non_neg_integer(), array() ) -> array(). @@ -196,12 +235,20 @@ bitarray_get(I, A) -> V = array:get(AI, A), (V band (1 bsl (I rem ?W))) =/= 0. +%%%^^^^^^^^^^ Bitarray representation - suitable for sparse arrays ^^^^^^^^^^ + encode(Bloom) -> - zlib:gzip(term_to_binary(Bloom)). + zlib:gzip(term_to_binary(bloom_build(Bloom))). decode(Bin) -> binary_to_term(zlib:gunzip(Bin)). +%%% Convert to external form. +bloom_build(Bloom=#bloom{a=Bitmasks}) -> + Bloom#bloom{a=[bitmask_build(X) || X <- Bitmasks]}; +bloom_build(Sbf=#sbf{b=Blooms}) -> + Sbf#sbf{b=[bloom_build(X) || X <- Blooms]}. + %% UNIT TESTS -ifdef(TEST). diff --git a/src/hanoidb_dense_bitmap.erl b/src/hanoidb_dense_bitmap.erl new file mode 100644 index 0000000..300ccf8 --- /dev/null +++ b/src/hanoidb_dense_bitmap.erl @@ -0,0 +1,43 @@ +-module(hanoidb_dense_bitmap). + +-export([new/1, set/2, build/1, unbuild/1, member/2]). +-define(BITS_PER_CELL, 32). + +-define(REPR_NAME, dense_bitmap). + +new(N) -> + Tab = ets:new(dense_bitmap, [private, set]), + Width = 1 + (N-1) div ?BITS_PER_CELL, + Value = erlang:make_tuple(Width+1, 0, [{1,?REPR_NAME}]), + ets:insert(Tab, Value), + {dense_bitmap_ets, N, Width, Tab}. + +%% Set a bit. +set(I, {dense_bitmap_ets, _,_, Tab}=DBM) -> + Cell = 2 + I div ?BITS_PER_CELL, + BitInCell = I rem ?BITS_PER_CELL, + Old = ets:lookup_element(Tab, ?REPR_NAME, Cell), + New = Old bor (1 bsl BitInCell), + ets:update_element(Tab, ?REPR_NAME, {Cell,New}), + DBM. + +build({dense_bitmap_ets, _, _, Tab}) -> + [Row] = ets:lookup(Tab, ?REPR_NAME), + ets:delete(Tab), + Row. + +unbuild(Row) when element(1,Row)==?REPR_NAME -> + Tab = ets:new(dense_bitmap, [private, set]), + ets:insert(Tab, Row), + {dense_bitmap_ets, undefined, undefined, Tab}. + +member(I, Row) when element(1,Row)==?REPR_NAME -> + Cell = 2 + I div ?BITS_PER_CELL, + BitInCell = I rem ?BITS_PER_CELL, + CellValue = element(Cell, Row), + CellValue band (1 bsl BitInCell) =/= 0; +member(I, {dense_bitmap_ets, _,_, Tab}) -> + Cell = 2 + I div ?BITS_PER_CELL, + BitInCell = I rem ?BITS_PER_CELL, + CellValue = ets:lookup_element(Tab, ?REPR_NAME, Cell), + CellValue band (1 bsl BitInCell) =/= 0. diff --git a/src/hanoidb_sparse_bitmap.erl b/src/hanoidb_sparse_bitmap.erl new file mode 100644 index 0000000..0b662dd --- /dev/null +++ b/src/hanoidb_sparse_bitmap.erl @@ -0,0 +1,43 @@ +-module(hanoidb_sparse_bitmap). +-export([new/1, set/2, member/2]). + +-define(REPR_NAME, sparse_bitmap). + +new(Bits) when is_integer(Bits), Bits>0 -> + {?REPR_NAME, Bits, []}. + +set(N, {?REPR_NAME, Bits, Tree}) -> + {?REPR_NAME, Bits, set_to_tree(N, 1 bsl (Bits-1), Tree)}. + +set_to_tree(N, HighestBit, Mask) when HighestBit<32 -> + Nbit = 1 bsl N, + case Mask of + []-> Nbit; + _ -> Nbit bor Mask + end; +set_to_tree(N, _HighestBit, []) -> N; +set_to_tree(N, HighestBit, [TLo|THi]) -> + pushdown(N, HighestBit, TLo, THi); +set_to_tree(N, _HighestBit, N) -> N; +set_to_tree(N, HighestBit, M) when is_integer(M) -> + set_to_tree(N, HighestBit, pushdown(M, HighestBit, [], [])). + +pushdown(N, HighestBit, TLo, THi) -> + NHigh = N band HighestBit, + if NHigh =:= 0 -> [set_to_tree(N, HighestBit bsr 1, TLo) | THi]; + true -> [TLo | set_to_tree(N bxor NHigh, HighestBit bsr 1, THi)] + end. + +member(N, {?REPR_NAME, Bits, Tree}) -> + member_in_tree(N, 1 bsl (Bits-1), Tree). + +member_in_tree(_N, _HighestBit, []) -> false; +member_in_tree(N, HighestBit, Mask) when HighestBit<32 -> + Nbit = 1 bsl N, + Nbit band Mask > 0; +member_in_tree(N, _HighestBit, M) when is_integer(M) -> N =:= M; +member_in_tree(N, HighestBit, [TLo|THi]) -> + NHigh = N band HighestBit, + if NHigh =:= 0 -> member_in_tree(N, HighestBit bsr 1, TLo); + true -> member_in_tree(N bxor NHigh, HighestBit bsr 1, THi) + end.