Library: Foundation
Package: Hashing
Header: Poco/HashStatistic.h
Description
HashStatistic class bundles statistical information on the current state of a HashTable
Member Summary
Member Functions: avgEntriesPerHash, avgEntriesPerHashExclZeroEntries, detailedEntriesPerHash, maxEntriesPerHash, maxPositionsOfTable, numberOfEntries, numberOfZeroPositions, toString
Constructors
HashStatistic
HashStatistic(
UInt32 tableSize,
UInt32 numEntries,
UInt32 numZeroEntries,
UInt32 maxEntry,
std::vector < UInt32 > details = std::vector < UInt32 > ()
);
Creates the HashStatistic.
Destructor
~HashStatistic 
virtual ~HashStatistic();
Destroys the HashStatistic.
Member Functions
avgEntriesPerHash 
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
avgEntriesPerHashExclZeroEntries
double avgEntriesPerHashExclZeroEntries() const;
Same as getAvgEntriesPerHash but hash values that contain no entry are ignored, getAvgEntriesPerHashExclZeroEntries >= getAvgEntriesPerHash will always be true.
detailedEntriesPerHash
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
maxEntriesPerHash
UInt32 maxEntriesPerHash() const;
Returns the maximum number of entries per hash value found in the current table.
maxPositionsOfTable
UInt32 maxPositionsOfTable() const;
Returns the maximum number of different hash values possible for the table
numberOfEntries
UInt32 numberOfEntries() const;
Returns the total number of entries currently stored in the HashTable
numberOfZeroPositions
UInt32 numberOfZeroPositions() const;
Returns the number of hash positions that contain no entry.
toString
std::string toString() const;
Converts the whole data structure into a string.