Redo log checkpointing. More...

#include <chrono>
#include <cstring>
#include "arch0arch.h"
#include "buf0buf.h"
#include "buf0flu.h"
#include "dict0dict.h"
#include "log0buf.h"
#include "log0chkp.h"
#include "log0encryption.h"
#include "log0files_io.h"
#include "log0log.h"
#include "log0recv.h"
#include "log0sys.h"
#include "log0test.h"
#include "log0types.h"
#include "log0write.h"
#include "mach0data.h"
#include "my_dbug.h"
#include "os0event.h"
#include "srv0mon.h"
#include "srv0srv.h"
#include "srv0start.h"
#include "ut0byte.h"

Functions
Log - coordination with buffer pool and oldest_lsn
static void	log_update_available_for_checkpoint_lsn (log_t &log)
	Updates lsn available for checkpoint. More...

static lsn_t	log_compute_available_for_checkpoint_lsn (const log_t &log)
	Calculates lsn at which we might write a next checkpoint. More...

Log - making checkpoints
static bool	log_should_checkpoint (log_t &log)
	Checks if checkpoint should be written. More...

static void	log_consider_checkpoint (log_t &log)
	Considers writing next checkpoint. More...

static void	log_consider_sync_flush (log_t &log)
	Considers requesting page cleaners to execute sync flush. More...

static void	log_checkpoint (log_t &log)
	Makes a checkpoint. More...

static std::chrono::steady_clock::duration	log_checkpoint_time_elapsed (const log_t &log)
	Calculates time that elapsed since last checkpoint. More...

static void	log_request_checkpoint_low (log_t &log, lsn_t requested_lsn)
	Requests a checkpoint written for lsn greater or equal to provided one. More...

static void	log_request_checkpoint_in_next_file_low (log_t &log)
	Requests a checkpoint written in the next log file (not in the one, to which current log.last_checkpoint_lsn belongs to). More...

static void	log_wait_for_checkpoint (const log_t &log, lsn_t lsn)
	Waits for checkpoint advanced to at least that lsn. More...

static bool	log_request_sync_flush (const log_t &log, lsn_t new_oldest)
	Requests for urgent flush of dirty pages, to advance oldest_lsn in flush lists to provided value. More...

void	log_set_dict_max_allowed_checkpoint_lsn (log_t &log, lsn_t max_lsn)
	Updates the field log.dict_max_allowed_checkpoint_lsn. More...

static lsn_t	log_determine_checkpoint_lsn (log_t &log)

dberr_t	log_files_next_checkpoint (log_t &log, lsn_t next_checkpoint_lsn)
	Writes the next checkpoint to the log file, by writing a single checkpoint header with the checkpoint lsn. More...

Log_checkpoint_header_no	log_next_checkpoint_header (Log_checkpoint_header_no checkpoint_header_no)
	Provides opposite checkpoint header number to the given checkpoint header number. More...

dberr_t	log_files_write_checkpoint_low (log_t &log, Log_file_handle &checkpoint_file_handle, Log_checkpoint_header_no checkpoint_header_no, lsn_t checkpoint_lsn)
	Writes checkpoint to the file containing the written checkpoint_lsn. More...

dberr_t	log_files_write_first_data_block_low (log_t &log, Log_file_handle &file_handle, lsn_t checkpoint_lsn, lsn_t file_start_lsn)
	Writes the first data block to the log file using the provided handle to the opened log file. More...

static bool	log_request_checkpoint_validate (const log_t &log)

void	log_request_checkpoint (log_t &log, bool sync)
	Requests a fuzzy checkpoint write (for currently available lsn). More...

void	log_request_checkpoint_in_next_file (log_t &log)
	Requests a checkpoint written in the next log file (not in the one, to which current log.last_checkpoint_lsn belongs to). More...

bool	log_request_latest_checkpoint (log_t &log, lsn_t &requested_lsn)
	Requests a checkpoint at the current lsn. More...

bool	log_make_latest_checkpoint (log_t &log)
	Make a checkpoint at the current lsn. More...

bool	log_make_latest_checkpoint ()
	Make a checkpoint at the current lsn. More...

lsn_t	log_sync_flush_lsn (log_t &log)
	Computes lsn up to which sync flush should be done or returns 0 if there is no need to execute sync flush now. More...

void	log_checkpointer (log_t *log_ptr)
	The log checkpointer thread routine. More...

lsn_t	log_get_checkpoint_age (const log_t &log)
	Calculates age of current checkpoint as number of bytes since last checkpoint. More...

Log - free check
sn_t	log_concurrency_margin (lsn_t log_capacity, bool &is_safe)
	Computes concurrency margin to be used within log_free_check calls, for a given redo log capacity (soft_logical_capacity). More...

void	log_update_concurrency_margin (log_t &log)
	Updates log.concurrency_margin and log.concurrency_margin_is_safe for the current capacity of the redo log and current innodb_thread_concurrency value. More...

void	log_update_limits_low (log_t &log)
	Updates log.free_check_limit_lsn in the log. More...

void	log_set_dict_persist_margin (log_t &log, sn_t margin)
	Updates log.dict_persist_margin and recompute free check limit. More...

lsn_t	log_free_check_margin (const log_t &log)
	Provides current margin used in the log_free_check calls. More...

lsn_t	log_free_check_capacity (const log_t &log, lsn_t free_check_margin)
	Computes capacity of redo log available until log_free_check() needs to wait. More...

lsn_t	log_free_check_capacity (const log_t &log)
	Computes capacity of redo log available until log_free_check() needs to wait. More...

void	log_free_check_wait (log_t &log)
	Waits until there is free space in log files which includes concurrency margin required for all threads. More...

void	log_free_check_validate ()
	Performs debug checks to validate some of the assumptions. More...

Detailed Description

Redo log checkpointing.

File consists of four groups:

Coordination between log and buffer pool (oldest_lsn).
Making checkpoints (including the log_checkpointer thread).
Free check.

Function Documentation

◆ log_checkpoint()

static void log_checkpoint ( log_t & log )

static

Makes a checkpoint.

Note that this function does not flush dirty blocks from the buffer pool. It only checks what is lsn of the oldest modification in the buffer pool, and writes information about the lsn in log files.

Parameters

[in,out] log redo log

◆ log_checkpoint_time_elapsed()

static std::chrono::steady_clock::duration log_checkpoint_time_elapsed ( const log_t & log )

static

Calculates time that elapsed since last checkpoint.

Returns: Time duration elapsed since the last checkpoint

◆ log_checkpointer()

void log_checkpointer ( log_t * log_ptr )

The log checkpointer thread routine.

Parameters

[in,out] log_ptr pointer to redo log

◆ log_compute_available_for_checkpoint_lsn()

static lsn_t log_compute_available_for_checkpoint_lsn ( const log_t & log )

static

Calculates lsn at which we might write a next checkpoint.

It does the best effort, but possibly the maximum allowed lsn, could be even bigger. That's because the order of dirty pages in flush lists has been relaxed, and we don't want to spend time on traversing the whole flush lists here.

Note that some flush lists could be empty, and some additions of dirty pages could be pending (threads have written data to the log buffer and became scheduled out just before adding the dirty pages). That's why the calculated value cannot be larger than the log.buf_dirty_pages_added_up_to_lsn (only up to this lsn value we are sure, that all the dirty pages have been added).

It is guaranteed, that the returned value will not be smaller than the log.last_checkpoint_lsn.

Returns: lsn for which we might write the checkpoint

◆ log_concurrency_margin()

sn_t log_concurrency_margin	(	lsn_t	log_capacity,
		bool &	is_safe
	)

Computes concurrency margin to be used within log_free_check calls, for a given redo log capacity (soft_logical_capacity).

Parameters

[in]	log_capacity	redo log capacity (soft)
[out]	is_safe	true iff the computed margin wasn't truncated because of too small log_capacity

Returns: the computed margin

◆ log_consider_checkpoint()

static void log_consider_checkpoint ( log_t & log )

static

Considers writing next checkpoint.

Checks if checkpoint should be written (using log_should_checkpoint()) and writes the checkpoint if that's the case.

◆ log_consider_sync_flush()

static void log_consider_sync_flush ( log_t & log )

static

Considers requesting page cleaners to execute sync flush.

◆ log_determine_checkpoint_lsn()

static lsn_t log_determine_checkpoint_lsn ( log_t & log )

static

◆ log_files_next_checkpoint()

dberr_t log_files_next_checkpoint	(	log_t &	log,
		lsn_t	lsn
	)

Writes the next checkpoint to the log file, by writing a single checkpoint header with the checkpoint lsn.

Flushes the file after the write and updates the log.last_checkpoint_lsn.

Remarks: Note that two checkpoint headers are used alternately for consecutive checkpoints. If InnoDB crashed during the write, it would still have the previous checkpoint info and recovery would work.

Parameters

[in,out]	log	redo log
[in]	lsn	writes checkpoint at this lsn

Returns: DB_SUCCESS or error

◆ log_files_write_checkpoint_low()

dberr_t log_files_write_checkpoint_low	(	log_t &	log,
		Log_file_handle &	checkpoint_file_handle,
		Log_checkpoint_header_no	checkpoint_header_no,
		lsn_t	next_checkpoint_lsn
	)

Writes checkpoint to the file containing the written checkpoint_lsn.

The checkpoint is written to the given checkpoint header. Unless InnoDB is starting: checkpointer, writer and files mutexes must be acquired before calling this function.

Parameters

[in,out]	log	redo log
[in]	checkpoint_file_handle	handle to opened file
[in]	checkpoint_header_no	checkpoint header to be written
[in]	next_checkpoint_lsn	the checkpoint lsn to write

Returns: DB_SUCCESS or error

◆ log_files_write_first_data_block_low()

dberr_t log_files_write_first_data_block_low	(	log_t &	log,
		Log_file_handle &	file_handle,
		lsn_t	checkpoint_lsn,
		lsn_t	file_start_lsn
	)

Writes the first data block to the log file using the provided handle to the opened log file.

The block is addressed by the given checkpoint_lsn, filled with 0x00 and its data length points to checkpoint_lsn inside, making the block logically empty.

Remarks: This is used only during creation of new log files.

Parameters

[in,out]	log	redo log
[in]	file_handle	handle to the opened log file
[in]	checkpoint_lsn	the checkpoint lsn
[in]	file_start_lsn	start_lsn of the file

Returns: DB_SUCCESS or error

◆ log_free_check_capacity() [1/2]

lsn_t log_free_check_capacity ( const log_t & log )

Computes capacity of redo log available until log_free_check() needs to wait.

It calls log_free_check_margin(log) to obtain the current log_free_check_margin.

Parameters

[in] log redo log

Returns: lsn capacity up to free_check_wait happens

◆ log_free_check_capacity() [2/2]

lsn_t log_free_check_capacity	(	const log_t &	log,
		lsn_t	free_check_margin
	)

Computes capacity of redo log available until log_free_check() needs to wait.

It uses a provided size of the log_free_check_margin.

Parameters

[in]	log	redo log
[in]	free_check_margin	size of the log_free_check_margin;

See also: log_free_check_margin(log)

Returns: lsn capacity up to free_check_wait happens

◆ log_free_check_margin()

lsn_t log_free_check_margin ( const log_t & log )

Provides current margin used in the log_free_check calls.

It is a sum of dict_persist_margin and concurrency_margin.

Parameters

[in] log redo log

Returns: margin that would be used in log_free_check()

◆ log_free_check_validate()

void log_free_check_validate ( )

Performs debug checks to validate some of the assumptions.

◆ log_free_check_wait()

void log_free_check_wait ( log_t & log )

Waits until there is free space in log files which includes concurrency margin required for all threads.

You should rather use log_free_check().

Parameters

[in] log redo log

◆ log_get_checkpoint_age()

lsn_t log_get_checkpoint_age ( const log_t & log )

Calculates age of current checkpoint as number of bytes since last checkpoint.

This includes bytes for headers and footers of all log blocks. The calculation is based on the latest written checkpoint lsn, and the current lsn, which points to the first non reserved data byte. Note that the current lsn could not fit the free space in the log files. This means that the checkpoint age could potentially be larger than capacity of the log files. However we do the best effort to avoid such situations, and if they happen, user threads wait until the space is reclaimed.

Parameters

[in] log redo log

Returns: checkpoint age as number of bytes

◆ log_make_latest_checkpoint() [1/2]

bool log_make_latest_checkpoint ( )

Make a checkpoint at the current lsn.

Reads current lsn and waits until all dirty pages have been flushed up to that lsn. Afterwards requests a checkpoint write and waits until it is finished.

Returns: true iff current lsn was greater than last checkpoint lsn

◆ log_make_latest_checkpoint() [2/2]

bool log_make_latest_checkpoint ( log_t & log )

Make a checkpoint at the current lsn.

Reads current lsn and waits until all dirty pages have been flushed up to that lsn. Afterwards requests a checkpoint write and waits until it is finished.

Parameters

[in,out] log redo log

Returns: true iff current lsn was greater than last checkpoint lsn

◆ log_next_checkpoint_header()

Log_checkpoint_header_no log_next_checkpoint_header ( Log_checkpoint_header_no checkpoint_header_no )

Provides opposite checkpoint header number to the given checkpoint header number.

Parameters

[in] checkpoint_header_no the given checkpoint header number

Returns: the opposite checkpoint header number

◆ log_request_checkpoint()

void log_request_checkpoint	(	log_t &	log,
		bool	sync
	)

Requests a fuzzy checkpoint write (for currently available lsn).

Parameters

[in,out]	log	redo log
[in]	sync	whether request is sync (function should wait)

◆ log_request_checkpoint_in_next_file()

void log_request_checkpoint_in_next_file ( log_t & log )

Requests a checkpoint written in the next log file (not in the one, to which current log.last_checkpoint_lsn belongs to).

Parameters

[in,out] log redo log

◆ log_request_checkpoint_in_next_file_low()

void log_request_checkpoint_in_next_file_low ( log_t & log )

static

Requests a checkpoint written in the next log file (not in the one, to which current log.last_checkpoint_lsn belongs to).

Prior to calling this function, caller must acquire the log.limits_mutex !

Parameters

[in,out] log redo log

◆ log_request_checkpoint_low()

static void log_request_checkpoint_low	(	log_t &	log,
		lsn_t	requested_lsn
	)

static

Requests a checkpoint written for lsn greater or equal to provided one.

The log.checkpointer_mutex has to be acquired before it is called, and it is not released within this function.

Parameters

[in,out]	log	redo log
[in]	requested_lsn	provided lsn (checkpoint should be not older)

◆ log_request_checkpoint_validate()

static bool log_request_checkpoint_validate ( const log_t & log )

static

◆ log_request_latest_checkpoint()

bool log_request_latest_checkpoint	(	log_t &	log,
		lsn_t &	requested_lsn
	)

Requests a checkpoint at the current lsn.

Parameters

[in,out]	log	redo log
[out]	requested_lsn	lsn for which checkpoint was requested, or stays unmodified if it wasn't requested

Returns: true iff requested (false if checkpoint_lsn was already at that lsn)

◆ log_request_sync_flush()

static bool log_request_sync_flush	(	const log_t &	log,
		lsn_t	new_oldest
	)

static

Requests for urgent flush of dirty pages, to advance oldest_lsn in flush lists to provided value.

This should force page cleaners to perform the sync-flush in which case the innodb_max_io_capacity is not respected. This should be called when we are close to running out of space in redo log (close to free_check_limit_lsn).

Parameters

[in]	log	redo log
[in]	new_oldest	oldest_lsn to stop flush at (or greater)

Return values

true	requested page flushing
false	did not request page flushing (either because it is unit test for redo log or sync flushing is disabled by sys_var: innodb_flush_sync)

◆ log_set_dict_max_allowed_checkpoint_lsn()

void log_set_dict_max_allowed_checkpoint_lsn	(	log_t &	log,
		lsn_t	max_lsn
	)

Updates the field log.dict_max_allowed_checkpoint_lsn.

This is limitation for lsn at which checkpoint might be written, imposed by cached changes to the DD table buffer. It is called from DD code.

Parameters

[in,out]	log	redo log
[in]	max_lsn	new value for the limitation

◆ log_set_dict_persist_margin()

void log_set_dict_persist_margin	(	log_t &	log,
		sn_t	margin
	)

Updates log.dict_persist_margin and recompute free check limit.

Parameters

[in,out]	log	redo log
[in]	margin	new value for log.dict_persist_margin

◆ log_should_checkpoint()

static bool log_should_checkpoint ( log_t & log )

static

Checks if checkpoint should be written.

Checks time elapsed since the last checkpoint, age of the last checkpoint and if there was any extra request to write the checkpoint (e.g. coming from log_make_latest_checkpoint()).

Returns: true if checkpoint should be written

◆ log_sync_flush_lsn()

lsn_t log_sync_flush_lsn ( log_t & log )

Computes lsn up to which sync flush should be done or returns 0 if there is no need to execute sync flush now.

Parameters

[in,out] log redo log

Returns: lsn for which we want to have oldest_lsn >= lsn in each BP, or 0 if there is no need for sync flush

◆ log_update_available_for_checkpoint_lsn()

static void log_update_available_for_checkpoint_lsn ( log_t & log )

static

Updates lsn available for checkpoint.

Parameters

[in,out] log redo log

◆ log_update_concurrency_margin()

void log_update_concurrency_margin ( log_t & log )

Updates log.concurrency_margin and log.concurrency_margin_is_safe for the current capacity of the redo log and current innodb_thread_concurrency value.

Parameters

[in,out] log redo log

◆ log_update_limits_low()

void log_update_limits_low ( log_t & log )

Updates log.free_check_limit_lsn in the log.

The log_limits_mutex must be acquired before a call (unless srv_is_being_started is true).

Parameters

[in,out] log redo log

◆ log_wait_for_checkpoint()

static void log_wait_for_checkpoint	(	const log_t &	log,
		lsn_t	lsn
	)

static

Waits for checkpoint advanced to at least that lsn.

Parameters

[in]	log	redo log
[in]	lsn	lsn up to which we are waiting

Functions

Detailed Description

Function Documentation

◆ log_checkpoint()

◆ log_checkpoint_time_elapsed()

◆ log_checkpointer()

◆ log_compute_available_for_checkpoint_lsn()

◆ log_concurrency_margin()

◆ log_consider_checkpoint()

◆ log_consider_sync_flush()

◆ log_determine_checkpoint_lsn()

◆ log_files_next_checkpoint()

◆ log_files_write_checkpoint_low()

◆ log_files_write_first_data_block_low()

◆ log_free_check_capacity() [1/2]

◆ log_free_check_capacity() [2/2]

◆ log_free_check_margin()

◆ log_free_check_validate()

◆ log_free_check_wait()

◆ log_get_checkpoint_age()

◆ log_make_latest_checkpoint() [1/2]

◆ log_make_latest_checkpoint() [2/2]

◆ log_next_checkpoint_header()

◆ log_request_checkpoint()

◆ log_request_checkpoint_in_next_file()

◆ log_request_checkpoint_in_next_file_low()

◆ log_request_checkpoint_low()

◆ log_request_checkpoint_validate()

◆ log_request_latest_checkpoint()

◆ log_request_sync_flush()

◆ log_set_dict_max_allowed_checkpoint_lsn()

◆ log_set_dict_persist_margin()

◆ log_should_checkpoint()

◆ log_sync_flush_lsn()

◆ log_update_available_for_checkpoint_lsn()

◆ log_update_concurrency_margin()

◆ log_update_limits_low()

◆ log_wait_for_checkpoint()