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
|
/**
* Copyright (C) 2023-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/util/indexed_string_vector.h"
#include "mongo/util/str.h"
namespace mongo {
// This method returns an array to be stored in '_fastHt'. This method also has the side-effect
// of initializing _stringToIndexMap. (This method assumes the default ctor for '_stringToIndexMap'
// has already executed.)
std::array<uint8_t, 128> IndexedStringVector::buildFastHash() {
_stringToIndexMap.clear();
// Initialize 'bf' to all zeros.
std::array<uint8_t, 128> fastHt = {{0}};
if (useFastHash()) {
for (size_t idx = 0; idx < _strings.size(); ++idx) {
auto& p = _strings[idx];
auto fastHash1 = computeFastHash1(p.data(), p.size());
auto fastHash2 = computeFastHash2(p.data(), p.size(), fastHash1);
size_t encodedIdx = idx + 2;
// Update 'fastHt[hash]' to store 'fieldIdx', or, in the case of a collision, '1'.
fastHt[fastHash1] = !fastHt[fastHash1] ? uint8_t(encodedIdx) : uint8_t(1);
fastHt[fastHash2] = !fastHt[fastHash2] ? uint8_t(encodedIdx) : uint8_t(1);
}
}
for (size_t idx = 0; idx < _strings.size(); ++idx) {
auto& p = _strings[idx];
if (useFastHash()) {
auto fastHash1 = computeFastHash1(p.data(), p.size());
auto fastHash2 = computeFastHash2(p.data(), p.size(), fastHash1);
size_t encodedIdx = idx + 2;
// If 'fastHt' can answer all queries about '_strings[idx]', then we don't need to
// add '_strings[idx]' to _stringToIndexMap.
if (fastHt[fastHash1] == encodedIdx || fastHt[fastHash2] == encodedIdx) {
continue;
}
}
auto [_, inserted] = _stringToIndexMap.emplace(StringData(p), idx);
tassert(
7582300,
str::stream()
<< "Input vector to IndexedStringVector contained multiple occurrences of string: "
<< p,
inserted);
}
return fastHt;
}
size_t IndexedStringVector::findInMapImpl(StringData str) const {
auto it = _stringToIndexMap.find(str);
return it != _stringToIndexMap.end() ? it->second : npos;
}
} // namespace mongo
|
