1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (the "License"); you may not use this file except in
%% compliance with the License. You may obtain a copy of the License
%% at http://www.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and
%% limitations under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developer of the Original Code is VMware, Inc.
%% Copyright (c) 2007-2012 VMware, Inc. All rights reserved.
%%
%% A dual-index tree.
%%
%% Conceptually, what we want is a map that has two distinct sets of
%% keys (referred to here as primary and secondary, although that
%% shouldn't imply a hierarchy) pointing to one set of
%% values. However, in practice what we'll always want to do is insert
%% a value that's pointed at by (one primary, many secondaries) and
%% remove values that are pointed at by (one secondary, many
%% primaries) or (one secondary, all primaries). Thus the API.
%%
%% Entries exists while they have a non-empty secondary key set. The
%% 'take' operations return the entries that got removed, i.e. that
%% had no remaining secondary keys. 'take' ignores missing supplied
%% keys.
-module(dtree).
-export([empty/0, insert/4, take/3, take/2, take_all/2,
is_defined/2, is_empty/1, smallest/1, size/1]).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-export_type([?MODULE/0]).
-opaque(?MODULE() :: {gb_tree(), gb_tree()}).
-type(pk() :: any()).
-type(sk() :: any()).
-type(val() :: any()).
-type(kv() :: {pk(), val()}).
-spec(empty/0 :: () -> ?MODULE()).
-spec(insert/4 :: (pk(), [sk()], val(), ?MODULE()) -> ?MODULE()).
-spec(take/3 :: ([pk()], sk(), ?MODULE()) -> {[kv()], ?MODULE()}).
-spec(take/2 :: (sk(), ?MODULE()) -> {[kv()], ?MODULE()}).
-spec(take_all/2 :: (sk(), ?MODULE()) -> {[kv()], ?MODULE()}).
-spec(is_defined/2 :: (sk(), ?MODULE()) -> boolean()).
-spec(is_empty/1 :: (?MODULE()) -> boolean()).
-spec(smallest/1 :: (?MODULE()) -> kv()).
-spec(size/1 :: (?MODULE()) -> non_neg_integer()).
-endif.
%%----------------------------------------------------------------------------
empty() -> {gb_trees:empty(), gb_trees:empty()}.
insert(PK, SKs, V, {P, S}) ->
{gb_trees:insert(PK, {gb_sets:from_list(SKs), V}, P),
lists:foldl(fun (SK, S0) ->
case gb_trees:lookup(SK, S0) of
{value, PKS} -> PKS1 = gb_sets:insert(PK, PKS),
gb_trees:update(SK, PKS1, S0);
none -> PKS = gb_sets:singleton(PK),
gb_trees:insert(SK, PKS, S0)
end
end, S, SKs)}.
take(PKs, SK, {P, S}) ->
case gb_trees:lookup(SK, S) of
none -> {[], {P, S}};
{value, PKS} -> TakenPKS = gb_sets:from_list(PKs),
PKSInter = gb_sets:intersection(PKS, TakenPKS),
PKSDiff = gb_sets:difference (PKS, TakenPKS),
{KVs, P1} = take2(PKSInter, SK, P),
{KVs, {P1, case gb_sets:is_empty(PKSDiff) of
true -> gb_trees:delete(SK, S);
false -> gb_trees:update(SK, PKSDiff, S)
end}}
end.
take(SK, {P, S}) ->
case gb_trees:lookup(SK, S) of
none -> {[], {P, S}};
{value, PKS} -> {KVs, P1} = take2(PKS, SK, P),
{KVs, {P1, gb_trees:delete(SK, S)}}
end.
take_all(SK, {P, S}) ->
case gb_trees:lookup(SK, S) of
none -> {[], {P, S}};
{value, PKS} -> {KVs, SKS, P1} = take_all2(PKS, P),
{KVs, {P1, prune(SKS, PKS, S)}}
end.
is_defined(SK, {_P, S}) -> gb_trees:is_defined(SK, S).
is_empty({P, _S}) -> gb_trees:is_empty(P).
smallest({P, _S}) -> {K, {_SKS, V}} = gb_trees:smallest(P),
{K, V}.
size({P, _S}) -> gb_trees:size(P).
%%----------------------------------------------------------------------------
take2(PKS, SK, P) ->
gb_sets:fold(fun (PK, {KVs, P0}) ->
{SKS, V} = gb_trees:get(PK, P0),
SKS1 = gb_sets:delete(SK, SKS),
case gb_sets:is_empty(SKS1) of
true -> KVs1 = [{PK, V} | KVs],
{KVs1, gb_trees:delete(PK, P0)};
false -> {KVs, gb_trees:update(PK, {SKS1, V}, P0)}
end
end, {[], P}, PKS).
take_all2(PKS, P) ->
gb_sets:fold(fun (PK, {KVs, SKS0, P0}) ->
{SKS, V} = gb_trees:get(PK, P0),
{[{PK, V} | KVs], gb_sets:union(SKS, SKS0),
gb_trees:delete(PK, P0)}
end, {[], gb_sets:empty(), P}, PKS).
prune(SKS, PKS, S) ->
gb_sets:fold(fun (SK0, S0) ->
PKS1 = gb_trees:get(SK0, S0),
PKS2 = gb_sets:difference(PKS1, PKS),
case gb_sets:is_empty(PKS2) of
true -> gb_trees:delete(SK0, S0);
false -> gb_trees:update(SK0, PKS2, S0)
end
end, S, SKS).
|
