Sample data buffer. More...

#include <health_monitor_stat_buffer.h>

Inheritance diagram for hm::Stat_Buffer< T >:

Public Member Functions
	Stat_Buffer ()=default

	Stat_Buffer (bool no_lock, PSI_memory_key memory_key)

	Stat_Buffer (PSI_rwlock_key rwlock_key, PSI_memory_key memory_key)

virtual	~Stat_Buffer ()

	Stat_Buffer (const Stat_Buffer &)=default

Stat_Buffer &	operator= (const Stat_Buffer &)=default

	Stat_Buffer (Stat_Buffer &&) noexcept=default

Stat_Buffer &	operator= (Stat_Buffer &&) noexcept=default

int	read (T &record, unsigned int row_num)
	Read an element of the stat buffer. More...

int	read_last (T &record)
	Read the last element of the stat buffer. More...

int	lock_read ()
	Acquire a read lock for a shared buffer. More...

void	unlock ()
	Unlock a read or write lock for a shared buffer. More...

int	read_no_lock (T &record, unsigned int row_num)
	Read an element from the circular buffer by logical row index. More...

int	read_impl (T &record, size_t row_num)

int	write (const T &record)
	Write one element into the circular buffer at the current head position. More...

int	write_impl (const T &record)

void	resize (size_t new_size)
	Resize the stat buffer, preserve the most recent data. More...

void	resize_impl (size_t new_size)

void	reset ()
	Reset the state of the buffer. More...

void	reset_no_lock ()
	Reset the buffer. More...

void	reset_impl ()

bool	map_logical_to_row_no_lock (uint64_t logical_idx, int &row_out) const
	Map a global logical index to the current ring-buffer row. More...

bool	map_logical_to_row (uint64_t logical_idx, int &row_out) const

bool	map_logical_to_row_impl (uint64_t logical_idx, int &row_out) const

mysql_rwlock_t *	get_rwlock ()

size_t	max_size () const

size_t	index () const

size_t	count () const

size_t	total_written () const

bool	full () const

bool	wrapped () const

Protected Attributes
std::unique_ptr< std::vector< T, Allocator > >	m_stats {nullptr}

size_t	m_max_size {0}

size_t	m_index {0}

size_t	m_count {0}

size_t	m_total_written {0}

bool	m_full {false}

bool	m_wrapped {false}

bool	m_no_lock {false}

PSI_rwlock_key	m_rwlock_key {0}

mysql_rwlock_t	m_rwlock

PSI_memory_key	m_memory_key {0}

Private Types
using	Allocator = Component_malloc_allocator< T >

Detailed Description

template<typename T>
class hm::Stat_Buffer< T >

Sample data buffer.

Member Typedef Documentation

◆ Allocator

template<typename T >

using hm::Stat_Buffer< T >::Allocator = Component_malloc_allocator<T>

private

Constructor & Destructor Documentation

◆ Stat_Buffer() [1/5]

template<typename T >

hm::Stat_Buffer< T >::Stat_Buffer ( )

default

◆ Stat_Buffer() [2/5]

template<typename T >

hm::Stat_Buffer< T >::Stat_Buffer	(	bool	no_lock,
		PSI_memory_key	memory_key
	)

inline

◆ Stat_Buffer() [3/5]

template<typename T >

hm::Stat_Buffer< T >::Stat_Buffer	(	PSI_rwlock_key	rwlock_key,
		PSI_memory_key	memory_key
	)

inline

◆ ~Stat_Buffer()

template<typename T >

virtual hm::Stat_Buffer< T >::~Stat_Buffer ( )

inlinevirtual

◆ Stat_Buffer() [4/5]

template<typename T >

hm::Stat_Buffer< T >::Stat_Buffer ( const Stat_Buffer< T > & )

default

◆ Stat_Buffer() [5/5]

template<typename T >

hm::Stat_Buffer< T >::Stat_Buffer ( Stat_Buffer< T > && )

defaultnoexcept

Member Function Documentation

◆ count()

template<typename T >

size_t hm::Stat_Buffer< T >::count ( ) const

inline

◆ full()

template<typename T >

bool hm::Stat_Buffer< T >::full ( ) const

inline

◆ get_rwlock()

template<typename T >

mysql_rwlock_t * hm::Stat_Buffer< T >::get_rwlock ( )

inline

◆ index()

template<typename T >

size_t hm::Stat_Buffer< T >::index ( ) const

inline

◆ lock_read()

template<typename T >

int hm::Stat_Buffer< T >::lock_read ( )

inline

Acquire a read lock for a shared buffer.

Returns: 0 success; 1 fail to set lock

◆ map_logical_to_row()

template<typename T >

bool hm::Stat_Buffer< T >::map_logical_to_row	(	uint64_t	logical_idx,
		int &	row_out
	)		const

inline

◆ map_logical_to_row_impl()

template<typename T >

bool hm::Stat_Buffer< T >::map_logical_to_row_impl	(	uint64_t	logical_idx,
		int &	row_out
	)		const

inline

◆ map_logical_to_row_no_lock()

template<typename T >

bool hm::Stat_Buffer< T >::map_logical_to_row_no_lock	(	uint64_t	logical_idx,
		int &	row_out
	)		const

inline

Map a global logical index to the current ring-buffer row.

This helper translates a monotonically increasing logical sample index (e.g. a global “next_metric”) into a window-relative row index [0..count-1] for the current contents of the buffer.

A logical index is considered “available” if it refers to an element that is still retained in the buffer (not yet overwritten.) If the logical index is older than the oldest existing element or newer than the most recent one, the mapping fails and the function returns false.

Thread safety:

Acquires the buffer’s read lock internally (if the buffer is shared) to provide a coherent snapshot of count() and total_written().

Parameters

[in]	logical_idx	Global monotonically increasing sample index.
[out]	row_out	On success, the row index in the range [0, count()) that corresponds to logical_idx.

Returns: true If logical_idx maps to a currently available row.; false If logical_idx is too old (overwritten) or not yet written.

Note: This function does not perform I/O. Use the returned row_out with read(record, row_out) to retrieve the element.

◆ max_size()

template<typename T >

size_t hm::Stat_Buffer< T >::max_size ( ) const

inline

◆ operator=() [1/2]

template<typename T >

Stat_Buffer & hm::Stat_Buffer< T >::operator= ( const Stat_Buffer< T > & )

default

◆ operator=() [2/2]

template<typename T >

Stat_Buffer & hm::Stat_Buffer< T >::operator= ( Stat_Buffer< T > && )

defaultnoexcept

◆ read()

template<typename T >

int hm::Stat_Buffer< T >::read	(	T &	record,
		unsigned int	row_num
	)

inline

Read an element of the stat buffer.

Parameters

[in,out]	record	Element from the buffer to be returned
[in]	row_num	Row number, zero-based

Returns: 0 success, 1 failure

◆ read_impl()

template<typename T >

int hm::Stat_Buffer< T >::read_impl	(	T &	record,
		size_t	row_num
	)

inline

◆ read_last()

template<typename T >

int hm::Stat_Buffer< T >::read_last ( T & record )

inline

Read the last element of the stat buffer.

Parameters

[in,out] record Element from the buffer to be returned

Returns: 0 success, 1 failure

◆ read_no_lock()

template<typename T >

int hm::Stat_Buffer< T >::read_no_lock	(	T &	record,
		unsigned int	row_num
	)

inline

Read an element from the circular buffer by logical row index.

The buffer holds up to m_count valid elements. This function accepts a row non-negative row_num range [0, m_count].

Thread safety:

If this buffer is shared (m_no_lock == false), the caller should hold a read lock or use read()/read_last() which manage locking.
This method itself does not acquire locks.

Parameters

[out]	record	On success, set to element at requested logical row.
[in]	row_num	Zero-based logical row index [0, m_count].

Returns: 0 on success.; 1 if the buffer is empty (no elements to read).

Note: Logical indexing: When the buffer has wrapped, the oldest element begins at m_index; otherwise it begins at 0.

◆ reset()

template<typename T >

void hm::Stat_Buffer< T >::reset ( )

inline

Reset the state of the buffer.

Existing elements will be overwritten.

◆ reset_impl()

template<typename T >

void hm::Stat_Buffer< T >::reset_impl ( )

inline

◆ reset_no_lock()

template<typename T >

void hm::Stat_Buffer< T >::reset_no_lock ( )

inline

Reset the buffer.

Assumes an active read_lock() if the buffer is shared.

◆ resize()

template<typename T >

void hm::Stat_Buffer< T >::resize ( size_t new_size )

inline

Resize the stat buffer, preserve the most recent data.

Note that m_stats is preallocated to m_max_size elements, so m_stats->size() is always the maximum size.

Parameters

[in] new_size Desired size of the buffer, can be either larger or smaller than the current size

◆ resize_impl()

template<typename T >

void hm::Stat_Buffer< T >::resize_impl ( size_t new_size )

inline

◆ total_written()

template<typename T >

size_t hm::Stat_Buffer< T >::total_written ( ) const

inline

◆ unlock()

template<typename T >

void hm::Stat_Buffer< T >::unlock ( )

inline

Unlock a read or write lock for a shared buffer.

◆ wrapped()

template<typename T >

bool hm::Stat_Buffer< T >::wrapped ( ) const

inline

◆ write()

template<typename T >

int hm::Stat_Buffer< T >::write ( const T & record )

inline

Write one element into the circular buffer at the current head position.

If the buffer is not yet full, the element is appended logically and the valid element count (m_count) increases. The head index (m_index) advances modulo the buffer size.

Once the buffer reaches capacity:

Subsequent writes overwrite the oldest element
m_full remains true
m_wrapped is set when the first overwrite occurs and stays true

Thread safety:

This method does not acquire locks. For shared buffers (m_no_lock == false), call write() which manages locking, or ensure the caller holds an exclusive lock.

Parameters

[in] record Element to write.

Returns: 0 on success.; 1 if the buffer has zero capacity (size() == 0).

Note: Uses logical indexing consistent with read_impl(): When not wrapped, the oldest element is at index 0. After wrapping, the oldest begins at m_index.

◆ write_impl()

template<typename T >

template<typename T >

size_t hm::Stat_Buffer< T >::m_total_written {0}

protected

◆ m_wrapped

template<typename T >

bool hm::Stat_Buffer< T >::m_wrapped {false}

protected

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

components/health_monitor/health_monitor_collector.h
components/health_monitor/health_monitor_stat_buffer.h

Public Member Functions

Protected Attributes

Private Types

Detailed Description

Member Typedef Documentation

◆ Allocator

Constructor & Destructor Documentation

◆ Stat_Buffer() [1/5]

◆ Stat_Buffer() [2/5]

◆ Stat_Buffer() [3/5]

◆ ~Stat_Buffer()

◆ Stat_Buffer() [4/5]

◆ Stat_Buffer() [5/5]

Member Function Documentation

◆ count()

◆ full()

◆ get_rwlock()

◆ index()

◆ lock_read()

◆ map_logical_to_row()

◆ map_logical_to_row_impl()

◆ map_logical_to_row_no_lock()

◆ max_size()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ read()

◆ read_impl()

◆ read_last()

◆ read_no_lock()

◆ reset()

◆ reset_impl()

◆ reset_no_lock()

◆ resize()

◆ resize_impl()

◆ total_written()

◆ unlock()

◆ wrapped()

◆ write()

◆ write_impl()

Member Data Documentation

◆ m_count

◆ m_full

◆ m_index

◆ m_max_size

◆ m_memory_key

◆ m_no_lock

◆ m_rwlock

◆ m_rwlock_key

◆ m_stats

◆ m_total_written

◆ m_wrapped