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