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Bloom filter: Introduce dispatch for handling multiple representations.

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This commit is contained in:
Erik Søe Sørensen 2012-09-25 14:28:31 +02:00
parent 5e69a0ca04
commit a475b5f5be
1 changed files with 18 additions and 3 deletions
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21
src/hanoidb_bloom.erl
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@ -87,7 +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).
@ -150,7 +150,7 @@ all_set(_Mask, _I1, _I, []) -> true;
all_set(Mask, I1, I, [H|T]) ->
case element(1, H) of
array ->
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
@ -185,7 +185,22 @@ 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) ->
bitarray_new(1 bsl LogN).
bitmask_set(I, BM) ->
case element(1,BM) of
array -> bitarray_set(I, BM)
end.
bitmask_get(I, BM) ->
case element(1,BM) of
array -> bitarray_get(I, BM)
end.
%%%========== Bitarray representation - suitable for sparse arrays ==========
bitarray_new(N) -> array:new((N-1) div ?W + 1, {default, 0}).