From d30133a87a29a18e93935e103c0fe1cb3aff7a12 Mon Sep 17 00:00:00 2001
From: Gregory Burd <greg@basho.com>
Date: Wed, 20 Jun 2012 11:04:10 +0100
Subject: [PATCH] Cleanup

---
 src/bloom.erl  | 58 ++++++++++++++++++++++++--------------------------
 src/ebloom.erl | 17 ++++++++-------
 2 files changed, 37 insertions(+), 38 deletions(-)

diff --git a/src/bloom.erl b/src/bloom.erl
index f7d8036..057464d 100644
--- a/src/bloom.erl
+++ b/src/bloom.erl
@@ -2,7 +2,7 @@
 %% @reference [http://en.wikipedia.org/wiki/Bloom_filter]
 
 -module(bloom).
--export([new/1, new/2, is_bloom/1, is_element/2, add_element/2, clear/1, count/1]).
+-export([new/1, new/2, is_bloom/1, is_element/2, add_element/2, clear/1, count/1, filter_size/1]).
 -import(math, [log/1, pow/2]).
 -import(erlang, [phash2/2]).
 
@@ -16,46 +16,46 @@
 -endif.
 
 -record(bloom, {
-    m      = 0,       % The size of the bitmap in bits.
-    bitmap = <<>>,    % The bitmap.
-    k      = 0,       % The number of hashes.
-    n      = 0,       % The maximum number of keys.
-    keys   = 0        % The current number of keys.
+    m      = 0     :: non_neg_integer(),       % The size of the bitmap in bits.
+    bitmap = <<>>  :: binary(),                % The bitmap.
+    k      = 0     :: non_neg_integer(),       % The number of hashes.
+    n      = 0     :: non_neg_integer(),       % The maximum number of keys.
+    keys   = 0     :: non_neg_integer()        % The current number of keys.
 }).
 
-%% @spec new(capacity) -> bloom().
 %% @equiv new(capacity, 0.001)
+-spec new(non_neg_integer()) -> #bloom{}.
 new(N) -> new(N, 0.001).
 
-%% @spec new(integer(), float()) -> bloom()
 %% @doc Creates a new Bloom filter, given a maximum number of keys and a
 %%     false-positive error rate.
+-spec new(non_neg_integer(), float()) -> #bloom{}.
 new(N, E) when N > 0, is_float(E), E > 0, E =< 1 ->
     {M, K} = calc_least_bits(N, E),
     #bloom{m=M, bitmap = <<0:((M+7) div 8 * 8)>>, k=K, n=N}.
 
-%% @spec clear(bloom()) -> bloom().
 %% @doc Creates a new empty Bloom filter from an existing one.
-clear(#bloom{#bitmap=Bitmap} = B) ->
-    B#bloom{<<0:bit_size(Bitmap)>>, n=0}.
+-spec clear(#bloom{}) -> #bloom{}.
+clear(#bloom{bitmap=Bitmap} = B) ->
+    B#bloom{bitmap = <<0:(erlang:bit_size(Bitmap))>>, n=0}.
 
-%% @spec count(bloom()) -> unsigned().
 %% @doc Returns the number of elements encoded into this Bloom filter.
-count(#bloom{#keys=N}) ->
+-spec count(#bloom{}) -> non_neg_integer().
+count(#bloom{keys=N}) ->
     N.
 
-%% @spec filter_size(bloom()) -> unsigned().
 %% @doc Returns the number of bits used in this Bloom filter.
-filter_size(#bloom{#bitmap=Bitmap}) ->
+-spec filter_size(#bloom{}) -> non_neg_integer().
+filter_size(#bloom{bitmap=Bitmap}) ->
     bit_size(Bitmap).
 
-%% @spec is_bloom(bloom()) -> bool()
 %% @doc Determines if the given argument is a bloom record.
+-spec is_bloom(#bloom{}) -> true | false.
 is_bloom(#bloom{}) -> true;
 is_bloom(_) -> false.
 
-%% @spec is_element(string(), bloom()) -> bool()
 %% @doc Determines if the key is (probably) an element of the filter.
+-spec is_element(term(), #bloom{}) -> true | false.
 is_element(Key, B) -> is_element(Key, B, calc_idxs(Key, B)).
 is_element(_, _, []) -> true;
 is_element(Key, B, [Idx | T]) ->
@@ -67,8 +67,8 @@ is_element(Key, B, [Idx | T]) ->
         false -> false
     end.
 
-%% @spec add_element(string(), bloom()) -> bloom()
 %% @doc Adds the key to the filter.
+-spec add_element(term(), #bloom{}) -> #bloom{}.
 add_element(Key, #bloom{keys=Keys, n=N, bitmap=Bitmap} = B) when Keys < N ->
     Idxs = calc_idxs(Key, B),
     Bitmap0 = set_bits(Bitmap, Idxs),
@@ -77,6 +77,9 @@ add_element(Key, #bloom{keys=Keys, n=N, bitmap=Bitmap} = B) when Keys < N ->
         false -> B#bloom{bitmap=Bitmap0, keys=Keys+1}
     end.
 
+%% @internal
+%% @doc Set the bits at the provided index(s) to "1" in the binary.
+-spec set_bits(binary(), list(non_neg_integer())) -> binary().
 set_bits(Bin, []) -> Bin;
 set_bits(Bin, [Idx | Idxs]) ->
     ByteIdx = Idx div 8,
@@ -85,16 +88,9 @@ set_bits(Bin, [Idx | Idxs]) ->
     Byte0 = Byte bor Mask,
     set_bits(<<Pre/binary, Byte0:8, Post/binary>>, Idxs).
 
-%% set2(N, Bin) ->
-%%     <<L:N/bits, _:1, R/bits>> = Bin,
-%%     <<L/bits, 1:1, R/bits>>.
-
-%% a(N, B) ->
-%%     fun (<<L:N/bits, _:1, R/bits>>) ->
-%%             <<L/bits, 1:1, R/bits>>
-%%     end(B).
-
-% Find the optimal bitmap size and number of hashes.
+%% @internal
+%% @doc Find the optimal bitmap size and number of hashes.
+%TODO -spec(non_neg_integer(), number()) -> non_neg_integer().
 calc_least_bits(N, E) -> calc_least_bits(N, E, 1, 0, 0).
 calc_least_bits(N, E, K, MinM, BestK) ->
     M = -1 * K * N / log(1 - pow(E, 1/K)),
@@ -105,8 +101,10 @@ calc_least_bits(N, E, K, MinM, BestK) ->
           _ -> calc_least_bits(N, E, K+1, CurM, CurK)
     end.
 
-% This uses the "enhanced double hashing" algorithm.
-% Todo: handle case of m > 2^32.
+%% @internal
+%% @doc This uses the "enhanced double hashing" algorithm.
+%% TODO: handle case of m > 2^32.
+%TODO -spec(term(), #bloom{}) -> list(non_neg_integer()).
 calc_idxs(Key, #bloom{m=M, k=K}) ->
     X = phash2(Key, M),
     Y = phash2({"salt", Key}, M),
diff --git a/src/ebloom.erl b/src/ebloom.erl
index ce60a4b..d0f4ccd 100644
--- a/src/ebloom.erl
+++ b/src/ebloom.erl
@@ -22,7 +22,7 @@
 %% the ebloom module.
 
 -module(ebloom).
--author('Dave Smith <dizzyd@dizzyd.com>').
+-author('Greg Burd <greg@burd.me>').
 
 -export([new/3,
          insert/2,
@@ -40,15 +40,16 @@
 
 -spec new(integer(), float(), integer()) -> {ok, reference()}.
 new(Count, FalseProb, _Seed) ->
-    bloom:new(Count, FalseProb).
+    {ok, bloom:new(Count, FalseProb)}.
 
 -spec insert(reference(), binary()) -> ok.
 insert(Ref, Bin) ->
-    bloom:add_element(Key, Ref).
+    bloom:add_element(Bin, Ref),
+    ok.
 
 -spec contains(reference(), binary()) -> true | false.
 contains(Ref, Bin) ->
-    is_element(Bin, Ref).
+    bloom:is_element(Bin, Ref).
 
 -spec clear(reference()) -> ok.
 clear(Ref) ->
@@ -64,19 +65,19 @@ elements(Ref) ->
 
 -spec effective_fpp(reference()) -> float().
 effective_fpp(_Ref) ->
-    raise not_yet_implemented.
+    throw(not_yet_implemented).
 
 -spec intersect(reference(), reference()) -> ok.
 intersect(_Ref, _OtherRef) ->
-    raise not_yet_implemented.
+    throw(not_yet_implemented).
 
 -spec union(reference(), reference()) -> ok.
 union(_Ref, _OtherRef) ->
-    raise not_yet_implemented.
+    throw(not_yet_implemented).
 
 -spec difference(reference(), reference()) -> ok.
 difference(_Ref, _OtherRef) ->
-    raise not_yet_implemented.
+    throw(not_yet_implemented).
 
 -spec serialize(reference()) -> binary().
 serialize(Ref) ->