Table_histograms Class Reference

The Table_histograms class represents a snapshot of the collection of histograms associated with a table. More...

#include <table_histograms.h>

Public Member Functions
	Table_histograms (Table_histograms &&)=delete
Table_histograms &	operator= (Table_histograms &&)=delete
	Table_histograms (const Table_histograms &)=delete
Table_histograms &	operator= (const Table_histograms &)=delete
	~Table_histograms ()=delete
void	destroy ()
	Destroys the object and frees memory. More...
const histograms::Histogram *	find_histogram (unsigned int field_index) const
	Perform a lookup in the local collection of histograms for a histogram on a given field. More...
bool	insert_histogram (unsigned int field_index, const histograms::Histogram *histogram)
	Copies the given histogram onto the local MEM_ROOT and inserts the copy into the local collection of histograms. More...

Static Public Member Functions
static Table_histograms *	create (PSI_memory_key psi_key) noexcept
	Factory method to create Table_histogram objects. More...

Private Member Functions
	Table_histograms ()=default
int	reference_count () const
	The number of TABLE objects referencing this object. More...
void	increment_reference_counter ()
void	decrement_reference_counter ()
int	get_index () const
	The index of this object in the Table_histograms_collection. More...
void	set_index (int index)

Private Attributes
MEM_ROOT	m_mem_root
mem_root_unordered_map< unsigned int, const histograms::Histogram * > *	m_histograms {nullptr}
int	m_reference_counter {0}
size_t	m_index {0}

Friends
class	Table_histograms_collection

Detailed Description

The Table_histograms class represents a snapshot of the collection of histograms associated with a table.

Table_histograms contains a reference counter to keep track of the number of TABLE objects that point to it.

Table_histogram objects are created using the static factory method create(). The object itself and everything it points to (including its MEM_ROOT) is allocated on its own MEM_ROOT. Table_histogram objects are destroyed/freed by calling destroy() that clears the MEM_ROOT.

Constructor & Destructor Documentation

Table_histograms() [1/3]

Table_histograms::Table_histograms ( )

privatedefault

Table_histograms() [2/3]

Table_histograms::Table_histograms ( Table_histograms &&  )

delete

Table_histograms() [3/3]

Table_histograms::Table_histograms ( const Table_histograms &  )

delete

~Table_histograms()

Table_histograms::~Table_histograms ( )

delete

Member Function Documentation

create()

Table_histograms * Table_histograms::create ( PSI_memory_key  psi_key )

staticnoexcept

Factory method to create Table_histogram objects.

Allocates a Table_histogram object on its own MEM_ROOT and returns a pointer. Should be matched by a call to destroy().

Parameters

psi_key

performance schema instrumentation memory key to track all memory used by the object.

Returns

A pointer to a Table_histograms object if construction was successful, returns nullptr otherwise.

decrement_reference_counter()

void Table_histograms::decrement_reference_counter ( )

inlineprivate

destroy()

void Table_histograms::destroy

(

)

Destroys the object and frees memory.

find_histogram()

const histograms::Histogram * Table_histograms::find_histogram

(

unsigned int

field_index

)

const

Perform a lookup in the local collection of histograms for a histogram on a given field.

Parameters

field_index

Index of the field to find a histogram for.

Returns

Pointer to a histogram or nullptr if no histogram was found.

get_index()

int Table_histograms::get_index ( void  ) const

inlineprivate

The index of this object in the Table_histograms_collection.

increment_reference_counter()

void Table_histograms::increment_reference_counter ( )

inlineprivate

insert_histogram()

bool Table_histograms::insert_histogram	(	unsigned int	field_index,
		const histograms::Histogram *	histogram
	)

Copies the given histogram onto the local MEM_ROOT and inserts the copy into the local collection of histograms.

Parameters

field_index	Index of the field to insert a histogram for.
histogram	Pointer to the histogram to be copied and inserted.

Returns

False if success, true on error.

operator=() [1/2]

Table_histograms & Table_histograms::operator= ( const Table_histograms &  )

delete

operator=() [2/2]

Table_histograms & Table_histograms::operator= ( Table_histograms &&  )

delete

reference_count()

int Table_histograms::reference_count ( ) const

inlineprivate

The number of TABLE objects referencing this object.

set_index()

void Table_histograms::set_index ( int  index )

inlineprivate

Friends And Related Function Documentation

Table_histograms_collection

friend class Table_histograms_collection

friend

Member Data Documentation

m_histograms

mem_root_unordered_map<unsigned int, const histograms::Histogram *>* Table_histograms::m_histograms {nullptr}

private

m_index

size_t Table_histograms::m_index {0}

private

m_mem_root

MEM_ROOT Table_histograms::m_mem_root

private

m_reference_counter

int Table_histograms::m_reference_counter {0}

private

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The documentation for this class was generated from the following files:

• sql/histograms/table_histograms.h
• sql/histograms/table_histograms.cc