Redo log functions related to the log buffer. More...

#include "log0sys.h"
#include "log0types.h"

Classes
struct	Log_handle
	Handle which is used for writes to the log buffer. More...

Functions
Log - writing to the log buffer.
Remarks These functions are designed for mtr_commit(), and used only there (except log0log-t.cc).
void	log_buffer_x_lock_enter (log_t &log)
	Acquires the log buffer x-lock. More...

void	log_buffer_x_lock_exit (log_t &log)
	Releases the log buffer x-lock. More...

Log_handle	log_buffer_reserve (log_t &log, size_t len)
	Reserves space in the redo log for following write operations. More...

lsn_t	log_buffer_write (log_t &log, const byte *str, size_t str_len, lsn_t start_lsn)
	Writes data to the log buffer. More...

void	log_buffer_write_completed (log_t &log, lsn_t start_lsn, lsn_t end_lsn, bool is_last_block)
	Adds a link start_lsn -> end_lsn to the log recent written buffer. More...

void	log_buffer_set_first_record_group (log_t &log, lsn_t rec_group_end_lsn)
	Modifies header of log block in the log buffer, which contains a given lsn value, and sets offset to the first group of log records within the block. More...

Log - management of the log buffer.
void	log_update_buf_limit (log_t &log)
	Updates limit used when writing to log buffer. More...

void	log_update_buf_limit (log_t &log, lsn_t write_lsn)
	Updates limit used when writing to log buffer, according to provided write_lsn. More...

void	log_buffer_flush_to_disk (log_t &log, bool sync=true)
	Write to the log file up to the last log entry. More...

void	log_buffer_flush_to_disk (bool sync=true)
	Requests flush of the log buffer. More...

void	log_buffer_sync_in_background ()
	Writes the log buffer to the log file. More...

void	log_buffer_get_last_block (log_t &log, lsn_t &last_lsn, byte *last_block, uint32_t &block_len)
	Get last redo block from redo buffer and end LSN. More...

bool	log_buffer_resize (log_t &log, size_t new_size)
	Changes size of the log buffer. More...

bool	log_buffer_resize_low (log_t &log, size_t new_size, lsn_t end_lsn)
	Changes size of the log buffer. More...

Log - the recent written buffer.
#define	log_closer_mutex_enter(log) mutex_enter(&((log).closer_mutex))

#define	log_closer_mutex_enter_nowait(log) mutex_enter_nowait(&((log).closer_mutex))

#define	log_closer_mutex_exit(log) mutex_exit(&((log).closer_mutex))

lsn_t	log_buffer_ready_for_write_lsn (const log_t &log)

lsn_t	log_buffer_wait_for_ready_for_write_lsn (log_t &log, lsn_t min_lsn, uint32_t *waits_on_event=nullptr)
	Wait until log_buffer_ready_for_write_lsn() returns at least min_lsn. More...

void	log_advance_ready_for_write_lsn (log_t &log)
	Advances log_buffer_ready_for_write_lsn() using links in the recent written buffer. More...

void	log_recent_written_empty_validate (const log_t &log, lsn_t begin, lsn_t end)
	Validates that all slots in log recent written buffer for lsn values in range between begin and end, are empty. More...

Detailed Description

Redo log functions related to the log buffer.

Macro Definition Documentation

◆ log_closer_mutex_enter

#define log_closer_mutex_enter ( log ) mutex_enter(&((log).closer_mutex))

◆ log_closer_mutex_enter_nowait

#define log_closer_mutex_enter_nowait ( log ) mutex_enter_nowait(&((log).closer_mutex))

◆ log_closer_mutex_exit

#define log_closer_mutex_exit ( log ) mutex_exit(&((log).closer_mutex))

Function Documentation

◆ log_advance_ready_for_write_lsn()

void log_advance_ready_for_write_lsn ( log_t & log )

Advances log_buffer_ready_for_write_lsn() using links in the recent written buffer.

It's used by the log writer thread only.

Parameters

[in] log redo log

◆ log_buffer_flush_to_disk() [1/2]

void log_buffer_flush_to_disk ( bool sync = true )

Requests flush of the log buffer.

Parameters

[in] sync true: wait until the flush is done

◆ log_buffer_flush_to_disk() [2/2]

void log_buffer_flush_to_disk	(	log_t &	log,
		bool	sync = `true`
	)

Write to the log file up to the last log entry.

Parameters

[in,out]	log	redo log
[in]	sync	whether we want the written log also to be flushed to disk.

◆ log_buffer_get_last_block()

void log_buffer_get_last_block	(	log_t &	log,
		lsn_t &	last_lsn,
		byte *	last_block,
		uint32_t &	block_len
	)

Get last redo block from redo buffer and end LSN.

Note that it takes x-lock on the log buffer for a short period. Out values are always set, even when provided last_block is nullptr.

Parameters

[in,out]	log	redo log
[out]	last_lsn	end lsn of last mtr
[out]	last_block	last redo block
[in,out]	block_len	length in bytes

◆ log_buffer_ready_for_write_lsn()

lsn_t log_buffer_ready_for_write_lsn ( const log_t & log )

inline

Returns: lsn up to which all writes to log buffer have been finished

◆ log_buffer_reserve()

Log_handle log_buffer_reserve	(	log_t &	log,
		size_t	len
	)

Reserves space in the redo log for following write operations.

Space is reserved for a given number of data bytes. Additionally bytes for required headers and footers of log blocks are reserved.

After the space is reserved, range of lsn values from a start_lsn to an end_lsn is assigned. The log writer thread cannot proceed further than to the start_lsn, until a link start_lsn -> end_lsn has been added to the log recent written buffer.

NOTE that the link is added after data is written to the reserved space in the log buffer. It is very critical to do all these steps as fast as possible, because very likely the log writer thread is waiting for the link.

Parameters

[in,out]	log	redo log
[in]	len	number of data bytes to reserve for write

Returns: handle that represents the reservation

◆ log_buffer_resize()

bool log_buffer_resize	(	log_t &	log,
		size_t	new_size
	)

Changes size of the log buffer.

This is a thread-safe version. It is used by SET GLOBAL innodb_log_buffer_size = X.

Parameters

[in,out]	log	redo log
[in]	new_size	requested new size

Returns: true iff succeeded in resize

◆ log_buffer_resize_low()

bool log_buffer_resize_low	(	log_t &	log,
		size_t	new_size,
		lsn_t	end_lsn
	)

Changes size of the log buffer.

This is a non-thread-safe version which might be invoked only when there are no concurrent possible writes to the log buffer. It is used in log_buffer_reserve() when a requested size to reserve is larger than size of the log buffer.

Parameters

[in,out]	log	redo log
[in]	new_size	requested new size
[in]	end_lsn	maximum lsn written to log buffer

Returns: true iff succeeded in resize

◆ log_buffer_set_first_record_group()

void log_buffer_set_first_record_group	(	log_t &	log,
		lsn_t	rec_group_end_lsn
	)

Modifies header of log block in the log buffer, which contains a given lsn value, and sets offset to the first group of log records within the block.

This is used by mtr after writing a log record group which ends at lsn belonging to different log block than lsn at which the group was started. When write was finished at the last data byte of log block, it is considered ended in the next log block, because the next data byte belongs to that block.

During recovery, when recovery is started in the middle of some group of log records, it first looks for the beginning of the next group.

Parameters

[in,out]	log	redo log
[in]	rec_group_end_lsn	lsn at which the first log record group starts within the block containing this lsn value

◆ log_buffer_sync_in_background()

void log_buffer_sync_in_background ( )

Writes the log buffer to the log file.

It is intended to be called from background master thread periodically. If the log writer threads are active, this function writes nothing.

◆ log_buffer_wait_for_ready_for_write_lsn()

lsn_t log_buffer_wait_for_ready_for_write_lsn	(	log_t &	log,
		lsn_t	min_lsn,
		uint32_t *	waits_on_event = `nullptr`
	)

Wait until log_buffer_ready_for_write_lsn() returns at least min_lsn.

Parameters

[in]	log	redo log
[in]	min_lsn	The awaited minimum value of log_buffer_ready_for_write_lsn().
[out]	waits_on_event	If not null, then the pointed integer will be set to the number of times this function had to wait on closer_event.

Returns: The seen value of log_buffer_ready_for_write_lsn() which was at least equal to min_lsn.

◆ log_buffer_write()

lsn_t log_buffer_write	(	log_t &	log,
		const byte *	str,
		size_t	str_len,
		lsn_t	start_lsn
	)

Writes data to the log buffer.

The space in the redo log has to be reserved before calling to this function and lsn pointing to inside the reserved range of lsn values has to be provided.

The write does not have to cover the whole reserved space, but may not overflow it. If it does not cover, then returned value should be used to start the next write operation. Note that finally we must use exactly all the reserved space.

Parameters

[in,out]	log	redo log
[in]	str	memory to write data from
[in]	str_len	number of bytes to write
[in]	start_lsn	lsn to start writing at (the reserved space)

Returns: end_lsn after writing the data (in the reserved space), could be used to start the next write operation if there is still free space in the reserved space

◆ log_buffer_write_completed()

void log_buffer_write_completed	(	log_t &	log,
		lsn_t	start_lsn,
		lsn_t	end_lsn,
		bool	is_last_block
	)

Adds a link start_lsn -> end_lsn to the log recent written buffer.

This function must be called after the data has been written to the fragment of log buffer represented by range [start_lsn, end_lsn). After the link is added, the log writer may write the data to disk.

NOTE that still dirty pages for the [start_lsn, end_lsn) are not added to flush lists when this function is called.

Parameters

[in,out]	log	redo log
[in]	start_lsn	start_lsn of the link to add
[in]	end_lsn	end_lsn of the link to add
[in]	is_last_block	A flag to let log writer know that this [start_lsn,end_lsn) range was the last fragment of the range reserved by this thread earlier through log_buffer_reserve(..) , i.e. this thread has finished writing to the log buffer.

◆ log_buffer_x_lock_enter()

void log_buffer_x_lock_enter ( log_t & log )

Acquires the log buffer x-lock.

Parameters

[in,out] log redo log

◆ log_buffer_x_lock_exit()

void log_buffer_x_lock_exit ( log_t & log )

Releases the log buffer x-lock.

Parameters

[in,out] log redo log

◆ log_recent_written_empty_validate()

void log_recent_written_empty_validate	(	const log_t &	log,
		lsn_t	begin,
		lsn_t	end
	)

Validates that all slots in log recent written buffer for lsn values in range between begin and end, are empty.

Used during tests, crashes the program if validation does not pass.

Parameters

[in]	log	redo log which buffer is validated
[in]	begin	validation start (inclusive)
[in]	end	validation end (exclusive)

◆ log_update_buf_limit() [1/2]

void log_update_buf_limit ( log_t & log )

Updates limit used when writing to log buffer.

Note that the log buffer may have space for log records for which we still do not have space in log files (for larger lsn values).

Parameters

[in,out] log redo log

◆ log_update_buf_limit() [2/2]

void log_update_buf_limit	(	log_t &	log,
		lsn_t	write_lsn
	)

Updates limit used when writing to log buffer, according to provided write_lsn.

It must be <= log.write_lsn.load() to protect from log buffer overwrites.

Parameters

[in,out]	log	redo log
[in]	write_lsn	value <= log.write_lsn.load()

Classes

Functions

Log - the recent written buffer.

Detailed Description

Macro Definition Documentation

◆ log_closer_mutex_enter

◆ log_closer_mutex_enter_nowait

◆ log_closer_mutex_exit

Function Documentation

◆ log_advance_ready_for_write_lsn()

◆ log_buffer_flush_to_disk() [1/2]

◆ log_buffer_flush_to_disk() [2/2]

◆ log_buffer_get_last_block()

◆ log_buffer_ready_for_write_lsn()

◆ log_buffer_reserve()

◆ log_buffer_resize()

◆ log_buffer_resize_low()

◆ log_buffer_set_first_record_group()

◆ log_buffer_sync_in_background()

◆ log_buffer_wait_for_ready_for_write_lsn()

◆ log_buffer_write()

◆ log_buffer_write_completed()

◆ log_buffer_x_lock_enter()

◆ log_buffer_x_lock_exit()

◆ log_recent_written_empty_validate()

◆ log_update_buf_limit() [1/2]

◆ log_update_buf_limit() [2/2]