1 | // |
2 | // HashStatistic.h |
3 | // |
4 | // Library: Foundation |
5 | // Package: Hashing |
6 | // Module: HashStatistic |
7 | // |
8 | // Definition of the HashStatistic class. |
9 | // |
10 | // Copyright (c) 2006, Applied Informatics Software Engineering GmbH. |
11 | // and Contributors. |
12 | // |
13 | // SPDX-License-Identifier: BSL-1.0 |
14 | // |
15 | |
16 | |
17 | #ifndef Foundation_HashStatistic_INCLUDED |
18 | #define Foundation_HashStatistic_INCLUDED |
19 | |
20 | |
21 | #include "Poco/Foundation.h" |
22 | #include <vector> |
23 | |
24 | |
25 | namespace Poco { |
26 | |
27 | |
28 | //@ deprecated |
29 | class Foundation_API HashStatistic |
30 | /// HashStatistic class bundles statistical information on the current state of a HashTable |
31 | { |
32 | public: |
33 | HashStatistic( |
34 | UInt32 tableSize, |
35 | UInt32 numEntries, |
36 | UInt32 numZeroEntries, |
37 | UInt32 maxEntry, |
38 | std::vector<UInt32> details = std::vector<UInt32>()); |
39 | /// Creates the HashStatistic. |
40 | |
41 | virtual ~HashStatistic(); |
42 | /// Destroys the HashStatistic. |
43 | |
44 | UInt32 maxPositionsOfTable() const; |
45 | /// Returns the maximum number of different hash values possible for the table |
46 | |
47 | UInt32 numberOfEntries() const; |
48 | /// Returns the total number of entries currently stored in the HashTable |
49 | |
50 | UInt32 numberOfZeroPositions() const; |
51 | /// Returns the number of hash positions that contain no entry. |
52 | |
53 | double avgEntriesPerHash() const; |
54 | /// Returns the average number of entries per position in the Hashtable, the higher this value the less efficient |
55 | /// performs hashing. If a large value is returned and getNumberOfZeroPositions also returns a large value, this |
56 | /// indicates an inefficient hashing function. If the number of zero entries is low, resizing the HashTable, should |
57 | /// be enough to improve performance |
58 | |
59 | double avgEntriesPerHashExclZeroEntries() const; |
60 | /// Same as getAvgEntriesPerHash but hash values that contain no entry are ignored, |
61 | /// getAvgEntriesPerHashExclZeroEntries >= getAvgEntriesPerHash will always be true. |
62 | |
63 | UInt32 maxEntriesPerHash() const; |
64 | /// Returns the maximum number of entries per hash value found in the current table. |
65 | |
66 | const std::vector<UInt32> detailedEntriesPerHash() const; |
67 | /// Will either be an empty vector or will contain for each possible hash value, the number of entries currently stored |
68 | |
69 | std::string toString() const; |
70 | /// Converts the whole data structure into a string. |
71 | |
72 | private: |
73 | UInt32 _sizeOfTable; |
74 | UInt32 _numberOfEntries; |
75 | UInt32 _numZeroEntries; |
76 | UInt32 _maxEntriesPerHash; |
77 | std::vector<UInt32> _detailedEntriesPerHash; |
78 | }; |
79 | |
80 | |
81 | inline UInt32 HashStatistic::maxPositionsOfTable() const |
82 | { |
83 | return _sizeOfTable; |
84 | } |
85 | |
86 | |
87 | inline UInt32 HashStatistic::numberOfEntries() const |
88 | { |
89 | return _numberOfEntries; |
90 | } |
91 | |
92 | |
93 | inline UInt32 HashStatistic::numberOfZeroPositions() const |
94 | { |
95 | return _numZeroEntries; |
96 | } |
97 | |
98 | |
99 | inline double HashStatistic::avgEntriesPerHash() const |
100 | { |
101 | return ((double) numberOfEntries()) / maxPositionsOfTable(); |
102 | } |
103 | |
104 | |
105 | inline double HashStatistic::avgEntriesPerHashExclZeroEntries() const |
106 | { |
107 | return ((double) numberOfEntries()) / (maxPositionsOfTable() - numberOfZeroPositions()); |
108 | } |
109 | |
110 | |
111 | inline UInt32 HashStatistic::maxEntriesPerHash() const |
112 | { |
113 | return _maxEntriesPerHash; |
114 | } |
115 | |
116 | |
117 | inline const std::vector<UInt32> HashStatistic::detailedEntriesPerHash() const |
118 | { |
119 | return _detailedEntriesPerHash; |
120 | } |
121 | |
122 | |
123 | } // namespace Poco |
124 | |
125 | |
126 | #endif // Foundation_HashStatistic_INCLUDED |
127 | |