Contiguous archived data for redo log or page tracking. More...

#include <arch0arch.h>

Classes
class	Recovery
	Recovery system data structure for the archiver. More...

Public Types
typedef std::function< dberr_t(uint64_t start_offset, byte *header)>	Get_file_header_callback
	Function responsible to format the header of a new file which is created, when the stream of data is written to a sequence of new files. More...

Public Member Functions
	Arch_Group (lsn_t start_lsn, uint header_len, ib_mutex_t *mutex)
	Constructor: Initialize members. More...

	~Arch_Group ()
	Destructor: Delete all files for non-durable archiving. More...

dberr_t	init_file_ctx (const char path, const char base_dir, const char *base_file, uint num_files, uint64_t file_size, Arch_group_uuid uuid)
	Initialize the file context for the archive group. More...

void	close_file_ctxs ()

void	disable (lsn_t end_lsn)
	Mark archive group inactive. More...

void	attach (bool is_durable)
	Attach a client to the archive group. More...

uint	detach (lsn_t stop_lsn, Arch_Page_Pos *stop_pos)
	Detach a client when archiving is stopped by the client. More...

void	release (bool is_durable)
	Release the archive group from a client. More...

dberr_t	build_active_file_name ()
	Construct file name for the active file which indicates whether a group is active or not. More...

dberr_t	build_durable_file_name ()
	Construct file name for the durable file which indicates whether a group was made durable or not. More...

int	mark_active ()
	Mark the group active by creating a file in the respective group directory. More...

int	mark_durable ()
	Mark the group durable by creating a file in the respective group directory. More...

int	mark_inactive ()
	Mark the group inactive by deleting the 'active' file. More...

bool	is_active () const
	Check if archiving is going on for this group. More...

dberr_t	write_file_header (byte *from_buffer, uint length)
	Write the header (RESET page) to an archived file. More...

dberr_t	write_to_file (Arch_File_Ctx from_file, byte from_buffer, uint length, bool partial_write, bool do_persist, Get_file_header_callback new_file)
	Archive data to one or more files. More...

bool	find_reset_point (lsn_t check_lsn, Arch_Point &reset_point)
	Find the appropriate reset LSN that is less than or equal to the given lsn and fetch the reset point. More...

bool	find_stop_point (lsn_t check_lsn, Arch_Point &stop_point, Arch_Page_Pos write_pos)
	Find the first stop LSN that is greater than the given LSN and fetch the stop point. More...

void	adjust_end_lsn (lsn_t &stop_lsn, uint32_t &blk_len)
	Adjust end LSN to end of file. More...

void	adjust_copy_length (lsn_t arch_lsn, uint32_t &copy_len)
	Adjust redo copy length to end of file. More...

bool	validate_info_in_files ()
	Check if the information maintained in the memory is the same as the information maintained in the files. More...

uint	get_file_count () const
	Get the total number of archived files belonging to this group. More...

bool	is_referenced () const
	Check if any client (durable or not) is attached to the archiver. More...

bool	is_durable_client_active () const
	Check if any client requiring durable archiving is active. More...

bool	is_durable () const
	Check if any client requires durable archiving. More...

uint	purge (lsn_t purge_lsn, lsn_t &purged_lsn)
	Purge archived files until the specified purge LSN. More...

void	save_reset_point_in_mem (lsn_t lsn, Arch_Page_Pos pos)
	Update the reset information in the in-memory structure that we maintain for faster access. More...

void	update_stop_point (Arch_Page_Pos pos, lsn_t stop_lsn)
	Update stop lsn of a file in the group. More...

dberr_t	recover (Arch_Recv_Group_Info &group_info, Arch_Dblwr_Ctx *dblwr_ctx)
	Recover the information belonging to this group from the archived files. More...

int	read_data (Arch_Page_Pos cur_pos, byte *buff, uint buff_len)
	Parse block for block info (header/data). More...

void	get_file_name (uint idx, char *name_buf, uint buf_len)
	Get archived file name at specific index in this group. More...

uint64_t	get_file_size () const
	Get the current file size for this group. More...

lsn_t	get_begin_lsn () const
	Get start LSN for this group. More...

lsn_t	get_end_lsn () const

Arch_Page_Pos	get_stop_pos () const

Arch_group_uuid	get_uuid () const

void	get_status (std::vector< std::pair< lsn_t, bool > > &status)
	Fetch the status of the page tracking system. More...

dberr_t	open_file (Arch_Page_Pos write_pos, bool create_new)
	Open the file which was open at the time of a crash, during crash recovery, and set the file offset to the last written offset. More...

	Arch_Group (Arch_Group const &)=delete
	Disable copy construction. More...

Arch_Group &	operator= (Arch_Group const &)=delete
	Disable assignment. More...

Static Public Member Functions
static dberr_t	init_dblwr_file_ctx (const char path, const char base_file, uint num_files, uint64_t file_size)
	Initialize the doublewrite buffer file context for the archive group. More...

static dberr_t	write_to_doublewrite_file (Arch_File_Ctx from_file, byte from_buffer, uint write_size, Arch_Page_Dblwr_Offset offset)
	Write to the doublewrite buffer before writing archived data to a file. More...

static void	shutdown ()
	Operations to be done at the time of shutdown. More...

Private Member Functions
int	read_from_file (Arch_Page_Pos read_pos, uint read_len, byte read_buff)
	Get page IDs from archived file. More...

void	get_dir_name (char *name_buf, uint buf_len)
	Get the directory name for this archive group. More...

dberr_t	prepare_file_with_header (uint64_t start_offset, Get_file_header_callback &get_header)
	Create a new file and write the header. More...

Private Attributes
bool	m_is_active {true}
	If the group is active. More...

char *	m_active_file_name {nullptr}
	To know which group was active at the time of a crash/shutdown during recovery we create an empty file in the group directory. More...

pfs_os_file_t	m_active_file
	File descriptor for a file required to indicate that the group was active at the time of crash during recovery . More...

char *	m_durable_file_name {nullptr}
	File name for the durable file which indicates whether a group was made durable or not. More...

pfs_os_file_t	m_durable_file
	File descriptor for a file to indicate that the group was made durable or not. More...

uint	m_ref_count {}
	Number of clients referencing the group. More...

uint	m_dur_ref_count {}
	Number of clients referencing for durable archiving. More...

uint	m_num_active {}
	Number of clients for which archiving is in progress. More...

lsn_t	m_begin_lsn {LSN_MAX}
	Start LSN for the archive group. More...

lsn_t	m_end_lsn {LSN_MAX}
	End lsn for this archive group. More...

Arch_Page_Pos	m_stop_pos {}
	Stop position of the group, if it's not active. More...

uint	m_header_len {}
	Header length for the archived files. More...

uint64_t	m_file_size
	Size of file used when a new file is being created. More...

Arch_group_uuid	m_uuid {}
	UUID generated for this arch group. More...

Arch_File_Ctx	m_file_ctx
	Archive file context. More...

ib_mutex_t *	m_arch_mutex
	Mutex protecting concurrent operations by multiple clients. More...

Static Private Attributes
static Arch_File_Ctx	s_dblwr_file_ctx
	Doublewrite buffer file context. More...

Detailed Description

Contiguous archived data for redo log or page tracking.

If there is a gap, that is if archiving is stopped and started, a new group is created.

Member Typedef Documentation

◆ Get_file_header_callback

typedef std::function<dberr_t(uint64_t start_offset, byte *header)> Arch_Group::Get_file_header_callback

Function responsible to format the header of a new file which is created, when the stream of data is written to a sequence of new files.

Parameters

[in]	start_offset	offset at which a new file starts, expressed in bytes from the beginning of the stream
[in]	header	header to format

Constructor & Destructor Documentation

◆ Arch_Group() [1/2]

Arch_Group::Arch_Group	(	lsn_t	start_lsn,
		uint	header_len,
		ib_mutex_t *	mutex
	)

inline

Constructor: Initialize members.

Parameters

[in]	start_lsn	start LSN for the group
[in]	header_len	length of header for archived files
[in]	mutex	archive system mutex from caller

◆ ~Arch_Group()

Arch_Group::~Arch_Group ( )

Destructor: Delete all files for non-durable archiving.

◆ Arch_Group() [2/2]

Arch_Group::Arch_Group ( Arch_Group const & )

delete

Disable copy construction.

Member Function Documentation

◆ adjust_copy_length()

void Arch_Group::adjust_copy_length	(	lsn_t	arch_lsn,
		uint32_t &	copy_len
	)

Adjust redo copy length to end of file.

This is used in debug mode to archive only till end of file.

Parameters

[in]	arch_lsn	LSN up to which data is already archived
[in,out]	copy_len	length of data to copy in bytes

◆ adjust_end_lsn()

void Arch_Group::adjust_end_lsn	(	lsn_t &	stop_lsn,
		uint32_t &	blk_len
	)

Adjust end LSN to end of file.

This is used in debug mode to test the case when LSN is at file boundary.

Parameters

[in,out]	stop_lsn	stop lsn for client
[out]	blk_len	last block length

◆ attach()

void Arch_Group::attach ( bool is_durable )

inline

Attach a client to the archive group.

Parameters

[in] is_durable true, if durable tracking is requested

◆ build_active_file_name()

dberr_t Arch_Group::build_active_file_name ( )

Construct file name for the active file which indicates whether a group is active or not.

Note: Used only by the page archiver.

Returns: error code.

◆ build_durable_file_name()

dberr_t Arch_Group::build_durable_file_name ( )

Construct file name for the durable file which indicates whether a group was made durable or not.

Note: Used only by the page archiver.

Returns: error code.

◆ close_file_ctxs()

void Arch_Group::close_file_ctxs ( )

inline

◆ detach()

uint Arch_Group::detach	(	lsn_t	stop_lsn,
		Arch_Page_Pos *	stop_pos
	)

inline

Detach a client when archiving is stopped by the client.

The client still has reference to the group so that the group is not destroyed when it retrieves the archived data. The reference is removed later by Arch_Group::release.

Parameters

[in]	stop_lsn	archive stop lsn for client
[in]	stop_pos	archive stop position for client. Used only by the page_archiver.

Returns: number of active clients

◆ disable()

void Arch_Group::disable ( lsn_t end_lsn )

inline

Mark archive group inactive.

A group is marked inactive by archiver background before entering into idle state ARCH_STATE_IDLE.

Parameters

[in] end_lsn lsn where redo archiving is stopped

◆ find_reset_point()

bool Arch_Group::find_reset_point	(	lsn_t	check_lsn,
		Arch_Point &	reset_point
	)

inline

Find the appropriate reset LSN that is less than or equal to the given lsn and fetch the reset point.

Parameters

[in]	check_lsn	LSN to be searched against
[out]	reset_point	reset position of the fetched reset point

Returns: true if the search was successful.

◆ find_stop_point()

bool Arch_Group::find_stop_point	(	lsn_t	check_lsn,
		Arch_Point &	stop_point,
		Arch_Page_Pos	write_pos
	)

inline

Find the first stop LSN that is greater than the given LSN and fetch the stop point.

Parameters

[in]	check_lsn	LSN to be searched against
[out]	stop_point	stop point
[in]	write_pos	latest write_pos

Returns: true if the search was successful.

◆ get_begin_lsn()

lsn_t Arch_Group::get_begin_lsn ( ) const

inline

Get start LSN for this group.

Returns: start LSN

◆ get_dir_name()

void Arch_Group::get_dir_name	(	char *	name_buf,
		uint	buf_len
	)

inlineprivate

Get the directory name for this archive group.

It is used for cleaning up the archive directory.

Parameters

[out]	name_buf	directory name and path. Caller must allocate the buffer.
[in]	buf_len	buffer length

◆ get_end_lsn()

lsn_t Arch_Group::get_end_lsn ( ) const

inline

Returns: stop LSN for this group

◆ get_file_count()

uint Arch_Group::get_file_count ( ) const

inline

Get the total number of archived files belonging to this group.

Returns: number of archived files

◆ get_file_name()

void Arch_Group::get_file_name	(	uint	idx,
		char *	name_buf,
		uint	buf_len
	)

inline

Get archived file name at specific index in this group.

Caller would use it to open and copy data from archived files.

Parameters

[in]	idx	file index in the group
[out]	name_buf	file name and path. Caller must allocate the buffer.
[in]	buf_len	allocated buffer length

◆ get_file_size()

uint64_t Arch_Group::get_file_size ( ) const

inline

Get the current file size for this group.

Fixed size files are used for archiving data in a group.

Returns: file size in bytes

◆ get_status()

void Arch_Group::get_status ( std::vector< std::pair< lsn_t, bool > > & status )

inline

Fetch the status of the page tracking system.

Parameters

[out] status vector of a pair of (ID, bool) where ID is the start/stop point and bool is true if the ID is a start point else false

◆ get_stop_pos()

Arch_Page_Pos Arch_Group::get_stop_pos ( ) const

inline

Returns: stop block position of the group.

◆ get_uuid()

Arch_group_uuid Arch_Group::get_uuid ( ) const

inline

Returns: uuid for the arch group

◆ init_dblwr_file_ctx()

dberr_t Arch_Group::init_dblwr_file_ctx	(	const char *	path,
		const char *	base_file,
		uint	num_files,
		uint64_t	file_size
	)

static

Initialize the doublewrite buffer file context for the archive group.

Parameters

[in]	path	path to the file
[in]	base_file	file name prefix
[in]	num_files	initial number of files
[in]	file_size	file size in bytes

Returns: error code.

◆ init_file_ctx()

dberr_t Arch_Group::init_file_ctx	(	const char *	path,
		const char *	base_dir,
		const char *	base_file,
		uint	num_files,
		uint64_t	file_size,
		Arch_group_uuid	uuid
	)

inline

Initialize the file context for the archive group.

File context keeps the archived data in files on disk. There is one file context for a archive group.

Parameters

[in]	path	path to the file
[in]	base_dir	directory name prefix
[in]	base_file	file name prefix
[in]	num_files	initial number of files
[in]	file_size	size of file used when a new file is created
[in]	uuid	uuid of this arch group or 0 if unknown

Returns: error code.

◆ is_active()

bool Arch_Group::is_active ( ) const

inline

Check if archiving is going on for this group.

Returns: true, if the group is active

◆ is_durable()

bool Arch_Group::is_durable ( ) const

inline

Check if any client requires durable archiving.

Returns: true if there is at least 1 client that requires durable archiving

◆ is_durable_client_active()

bool Arch_Group::is_durable_client_active ( ) const

inline

Check if any client requiring durable archiving is active.

Returns: true if any durable client is still attached, else false

◆ is_referenced()

bool Arch_Group::is_referenced ( ) const

inline

Check if any client (durable or not) is attached to the archiver.

Returns: true if any client is attached, else false

◆ mark_active()

int Arch_Group::mark_active ( )

Mark the group active by creating a file in the respective group directory.

This is required at the time of recovery to know whether a group was active or not in case of a crash.

Note: Used only by the page archiver.

Returns: error code.

◆ mark_durable()

int Arch_Group::mark_durable ( )

Mark the group durable by creating a file in the respective group directory.

This is required at the time of recovery to differentiate durable group from group left over by crash during clone operation.

Note: Used only by the page archiver.

Returns: error code.

◆ mark_inactive()

int Arch_Group::mark_inactive ( )

Mark the group inactive by deleting the 'active' file.

This is required at the time of crash recovery to know whether a group was active or not in case of a crash.

Note: Used only by the page archiver.

Returns: error code

◆ open_file()

dberr_t Arch_Group::open_file	(	Arch_Page_Pos	write_pos,
		bool	create_new
	)

Open the file which was open at the time of a crash, during crash recovery, and set the file offset to the last written offset.

Parameters

[in]	write_pos	latest write position at the time of crash/shutdown
[in]	create_new	create new file if file not present

Returns: error code.

◆ operator=()

Arch_Group & Arch_Group::operator= ( Arch_Group const & )

delete

Disable assignment.

◆ prepare_file_with_header()

dberr_t Arch_Group::prepare_file_with_header	(	uint64_t	start_offset,
		Get_file_header_callback &	get_header
	)

private

Create a new file and write the header.

Parameters

[in]	start_offset	start offste
[in]	get_header	callback which prepares a header

◆ purge()

uint Arch_Group::purge	(	lsn_t	purge_lsn,
		lsn_t &	purged_lsn
	)

Purge archived files until the specified purge LSN.

Parameters

[in]	purge_lsn	LSN until which archived files needs to be purged
[out]	purged_lsn	LSN until which purging is successful; LSN_MAX if there was no purging done

Returns: error code

For a group (active or non-active) if there are any non-durable clients attached then we don't purge the group at all.

◆ read_data()

int Arch_Group::read_data	(	Arch_Page_Pos	cur_pos,
		byte *	buff,
		uint	buff_len
	)

Parse block for block info (header/data).

Parameters

[in]	cur_pos	position to read
[in,out]	buff	buffer into which to write the parsed data
[in]	buff_len	length of the buffer

Returns: error code

◆ read_from_file()

int Arch_Group::read_from_file	(	Arch_Page_Pos *	read_pos,
		uint	read_len,
		byte *	read_buff
	)

private

Get page IDs from archived file.

Parameters

[in]	read_pos	position to read from
[in]	read_len	length of data to read
[in]	read_buff	buffer to read page IDs

Returns: error code

◆ recover()

dberr_t Arch_Group::recover	(	Arch_Recv_Group_Info &	group_info,
		Arch_Dblwr_Ctx *	dblwr_ctx
	)

Recover the information belonging to this group from the archived files.

Parameters

[in,out]	group_info	structure containing information of a group obtained during recovery by scanning files
[in]	dblwr_ctx	file context related to doublewrite buffer

Returns: error code

◆ release()

void Arch_Group::release ( bool is_durable )

inline

Release the archive group from a client.

Reduce the reference count. When all clients release the group, the reference count falls down to zero. The function would then return zero and the caller can remove the group.

Parameters

[in] is_durable the client needs durable archiving

◆ save_reset_point_in_mem()

void Arch_Group::save_reset_point_in_mem	(	lsn_t	lsn,
		Arch_Page_Pos	pos
	)

inline

Update the reset information in the in-memory structure that we maintain for faster access.

Parameters

[in]	lsn	lsn at the time of reset
[in]	pos	pos at the time of reset

◆ shutdown()

static void Arch_Group::shutdown ( )

inlinestatic

Operations to be done at the time of shutdown.

◆ update_stop_point()

void Arch_Group::update_stop_point	(	Arch_Page_Pos	pos,
		lsn_t	stop_lsn
	)

inline

Update stop lsn of a file in the group.

Parameters

[in]	pos	stop position
[in]	stop_lsn	stop point

◆ validate_info_in_files()

bool Arch_Group::validate_info_in_files ( )

Check if the information maintained in the memory is the same as the information maintained in the files.

Returns: true if both sets of information are the same

◆ write_file_header()

dberr_t Arch_Group::write_file_header	(	byte *	from_buffer,
		uint	length
	)

Write the header (RESET page) to an archived file.

Note: Used only by the Page Archiver and not by the Redo Log Archiver.

Parameters

[in]	from_buffer	buffer to copy data
[in]	length	size of data to copy in bytes

Note: Used only by the Page Archiver.

Returns: error code

◆ write_to_doublewrite_file()

dberr_t Arch_Group::write_to_doublewrite_file	(	Arch_File_Ctx *	from_file,
		byte *	from_buffer,
		uint	write_size,
		Arch_Page_Dblwr_Offset	offset
	)

static

Write to the doublewrite buffer before writing archived data to a file.

The source is either a file context or buffer. Caller must ensure that data is in single file in source file context.

Parameters

[in]	from_file	file context to copy data from
[in]	from_buffer	buffer to copy data or NULL
[in]	write_size	size of data to write in bytes
[in]	offset	offset from where to write

Note: Used only by the Page Archiver.

Returns: error code

◆ write_to_file()

dberr_t Arch_Group::write_to_file	(	Arch_File_Ctx *	from_file,
		byte *	from_buffer,
		uint	length,
		bool	partial_write,
		bool	do_persist,
		Get_file_header_callback	new_file
	)

Archive data to one or more files.

The source is either a file context or buffer. Caller must ensure that data is in single file in source file context.

Parameters

[in]	from_file	file context to copy data from
[in]	from_buffer	buffer to copy data or NULL
[in]	length	size of data to copy in bytes
[in]	partial_write	true if the operation is part of partial flush
[in]	do_persist	doublewrite to ensure persistence
[in]	new_file	callback called for each new file being created

Returns: error code

Member Data Documentation

◆ m_active_file

pfs_os_file_t Arch_Group::m_active_file

private

File descriptor for a file required to indicate that the group was active at the time of crash during recovery .

◆ m_active_file_name

char* Arch_Group::m_active_file_name {nullptr}

private

To know which group was active at the time of a crash/shutdown during recovery we create an empty file in the group directory.

This holds the name of the file.

◆ m_arch_mutex

ib_mutex_t* Arch_Group::m_arch_mutex

private

Mutex protecting concurrent operations by multiple clients.

This is either the redo log or page archive system mutex. Currently used for assert checks.

◆ m_begin_lsn

lsn_t Arch_Group::m_begin_lsn {LSN_MAX}

private

Start LSN for the archive group.

◆ m_dur_ref_count

uint Arch_Group::m_dur_ref_count {}

private

Number of clients referencing for durable archiving.

◆ m_durable_file

pfs_os_file_t Arch_Group::m_durable_file

private

File descriptor for a file to indicate that the group was made durable or not.

Required to differentiate durable group from group left over by crash during clone operation.

◆ m_durable_file_name

char* Arch_Group::m_durable_file_name {nullptr}

private

File name for the durable file which indicates whether a group was made durable or not.

Required to differentiate durable group from group left over by crash during clone operation.

◆ m_end_lsn

lsn_t Arch_Group::m_end_lsn {LSN_MAX}

private

End lsn for this archive group.

◆ m_file_ctx

Arch_File_Ctx Arch_Group::m_file_ctx

private

Archive file context.

◆ m_file_size

uint64_t Arch_Group::m_file_size

private

Size of file used when a new file is being created.

◆ m_header_len

uint Arch_Group::m_header_len {}

private

Header length for the archived files.

◆ m_is_active

bool Arch_Group::m_is_active {true}

private

If the group is active.

◆ m_num_active

uint Arch_Group::m_num_active {}

private

Number of clients for which archiving is in progress.

◆ m_ref_count

uint Arch_Group::m_ref_count {}

private

Number of clients referencing the group.

◆ m_stop_pos

Arch_Page_Pos Arch_Group::m_stop_pos {}

private

Stop position of the group, if it's not active.

◆ m_uuid

Arch_group_uuid Arch_Group::m_uuid {}

private

UUID generated for this arch group.

◆ s_dblwr_file_ctx

Arch_File_Ctx Arch_Group::s_dblwr_file_ctx

staticprivate

Doublewrite buffer file context.

Note - Used only in the case of page archiver.

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

storage/innobase/include/arch0arch.h
storage/innobase/arch/arch0arch.cc
storage/innobase/arch/arch0log.cc
storage/innobase/arch/arch0page.cc
storage/innobase/arch/arch0recv.cc

Classes

Public Types

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Static Private Attributes

Detailed Description

Member Typedef Documentation

◆ Get_file_header_callback

Constructor & Destructor Documentation

◆ Arch_Group() [1/2]

◆ ~Arch_Group()

◆ Arch_Group() [2/2]

Member Function Documentation

◆ adjust_copy_length()

◆ adjust_end_lsn()

◆ attach()

◆ build_active_file_name()

◆ build_durable_file_name()

◆ close_file_ctxs()

◆ detach()

◆ disable()

◆ find_reset_point()

◆ find_stop_point()

◆ get_begin_lsn()

◆ get_dir_name()

◆ get_end_lsn()

◆ get_file_count()

◆ get_file_name()

◆ get_file_size()

◆ get_status()

◆ get_stop_pos()

◆ get_uuid()

◆ init_dblwr_file_ctx()

◆ init_file_ctx()

◆ is_active()

◆ is_durable()

◆ is_durable_client_active()

◆ is_referenced()

◆ mark_active()

◆ mark_durable()

◆ mark_inactive()

◆ open_file()

◆ operator=()

◆ prepare_file_with_header()

◆ purge()

◆ read_data()

◆ read_from_file()

◆ recover()

◆ release()

◆ save_reset_point_in_mem()

◆ shutdown()

◆ update_stop_point()

◆ validate_info_in_files()

◆ write_file_header()

◆ write_to_doublewrite_file()

◆ write_to_file()

Member Data Documentation

◆ m_active_file

◆ m_active_file_name

◆ m_arch_mutex

◆ m_begin_lsn

◆ m_dur_ref_count

◆ m_durable_file

◆ m_durable_file_name

◆ m_end_lsn

◆ m_file_ctx

◆ m_file_size

◆ m_header_len

◆ m_is_active

◆ m_num_active

◆ m_ref_count

◆ m_stop_pos

◆ m_uuid

◆ s_dblwr_file_ctx