poco/Foundation/include/Poco/HashStatistic.h
Matej Kenda f24547cdcf enh(Poco): Mark deprecated functionality with C++ attributes and resolve internal usage of deprecated functions (#4551)
* enh(poco): Replace deprecated comments with C++ deprecated attribute.

* enh(Poco): Replace some deprecated functionality in Poco sources. (#4426)

* enh(Poco): Replace more deprecated functionality in Poco sources. (#4426)

* fix(CMake): Variable BUILD_SHARED_LIBS must be defined properly to create valid binaries.

* enh: Code improvements done while resolving deprecated functionality (#4426)

* Un-deprecate LocalDateTme (#4426)

* enh(Poco): Replace usage of deprecated functionality with other functions/classes (#4426)

* chore(SSL): temporarily un-deprecate SSL-related functionality (#4426)

* chore(SSL): temporarily un-deprecate old MongoDB protocol functionality (#4426)

* enh(Poco): Minor Hash improvements (#4426)

* enh(Foundation): Compile deprecated hash tests only when POCO_TEST_DEPRECATED is enabled (#4426)

* enh(Net): Compile deprecated Socket::select functionality only when POCO_TEST_DEPRECATED is enabled (#4426)

* enh(Bonjour): Replace deprecated Socket::select with PollSet (#4426)

* enh(Poco): Introduce POCO_DEPRECATED macro to have the ability to disable deprecation warnings in applications (#4426)

* test(ODBC): add few asserts to testStoredProcedureDynamicVar

* fix(ODBC): rename DynamicAny -> DynamicVar in tests

* fix(ODBC): make Dignostics static members inline to prevent explicit instantiation warnings on windows

---------

Co-authored-by: Alex Fabijanic <alex@pocoproject.org>
2024-07-29 08:37:35 +02:00

127 lines
3.1 KiB
C++

//
// 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 {
class POCO_DEPRECATED("") HashStatistic;
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