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129 lines
3.2 KiB
C++
129 lines
3.2 KiB
C++
//
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// HashStatistic.h
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//
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// $Id: //poco/1.4/Foundation/include/Poco/HashStatistic.h#1 $
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//
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// Library: Foundation
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// Package: Hashing
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// Module: HashStatistic
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//
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// Definition of the HashStatistic class.
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//
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// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_HashStatistic_INCLUDED
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#define Foundation_HashStatistic_INCLUDED
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#include "Poco/Foundation.h"
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#include <vector>
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namespace Poco {
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//@ deprecated
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class Foundation_API HashStatistic
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/// HashStatistic class bundles statistical information on the current state of a HashTable
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{
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public:
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HashStatistic(
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UInt32 tableSize,
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UInt32 numEntries,
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UInt32 numZeroEntries,
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UInt32 maxEntry,
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std::vector<UInt32> details = std::vector<UInt32>());
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/// Creates the HashStatistic.
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virtual ~HashStatistic();
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/// Destroys the HashStatistic.
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UInt32 maxPositionsOfTable() const;
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/// Returns the maximum number of different hash values possible for the table
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UInt32 numberOfEntries() const;
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/// Returns the total number of entries currently stored in the HashTable
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UInt32 numberOfZeroPositions() const;
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/// Returns the number of hash positions that contain no entry.
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double avgEntriesPerHash() const;
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/// Returns the average number of entries per position in the Hashtable, the higher this value the less efficient
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/// performs hashing. If a large value is returned and getNumberOfZeroPositions also returns a large value, this
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/// indicates an inefficient hashing function. If the number of zero entries is low, resizing the HashTable, should
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/// be enough to improve performance
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double avgEntriesPerHashExclZeroEntries() const;
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/// Same as getAvgEntriesPerHash but hash values that contain no entry are ignored,
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/// getAvgEntriesPerHashExclZeroEntries >= getAvgEntriesPerHash will always be true.
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UInt32 maxEntriesPerHash() const;
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/// Returns the maximum number of entries per hash value found in the current table.
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const std::vector<UInt32> detailedEntriesPerHash() const;
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/// Will either be an empty vector or will contain for each possible hash value, the number of entries currently stored
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std::string toString() const;
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/// Converts the whole data structure into a string.
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private:
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UInt32 _sizeOfTable;
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UInt32 _numberOfEntries;
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UInt32 _numZeroEntries;
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UInt32 _maxEntriesPerHash;
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std::vector<UInt32> _detailedEntriesPerHash;
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};
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inline UInt32 HashStatistic::maxPositionsOfTable() const
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{
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return _sizeOfTable;
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}
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inline UInt32 HashStatistic::numberOfEntries() const
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{
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return _numberOfEntries;
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}
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inline UInt32 HashStatistic::numberOfZeroPositions() const
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{
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return _numZeroEntries;
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}
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inline double HashStatistic::avgEntriesPerHash() const
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{
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return ((double) numberOfEntries()) / maxPositionsOfTable();
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}
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inline double HashStatistic::avgEntriesPerHashExclZeroEntries() const
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{
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return ((double) numberOfEntries()) / (maxPositionsOfTable() - numberOfZeroPositions());
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}
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inline UInt32 HashStatistic::maxEntriesPerHash() const
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{
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return _maxEntriesPerHash;
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}
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inline const std::vector<UInt32> HashStatistic::detailedEntriesPerHash() const
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{
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return _detailedEntriesPerHash;
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}
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} // namespace Poco
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#endif // Foundation_HashStatistic_INCLUDED
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