Redo log - the main header. More...

#include "log0files_capacity.h"
#include "log0files_dict.h"
#include "log0files_finder.h"
#include "log0files_governor.h"
#include "log0files_io.h"
#include "log0sys.h"
#include "log0types.h"

Functions
Log - LSN computations.
constexpr lsn_t	log_translate_sn_to_lsn (sn_t sn)
	Calculates lsn value for given sn value. More...

sn_t	log_translate_lsn_to_sn (lsn_t lsn)
	Calculates sn value for given lsn value. More...

bool	log_is_data_lsn (lsn_t lsn)
	Validates a given lsn value. More...

Log - general functions.
static sn_t	log_get_sn (const log_t &log)

lsn_t	log_get_lsn (const log_t &log)
	Gets the current lsn value. More...

void	log_wait_for_space (log_t &log, sn_t end_sn)
	Waits until there is free space for range of sn values ending at the provided sn, in both the log buffer and in the log files. More...

void	log_print (const log_t &log, FILE *file)
	Prints information about important lsn values used in the redo log, and some statistics about speed of writing and flushing of data. More...

void	log_refresh_stats (log_t &log)
	Refreshes the statistics used to print per-second averages in log_print(). More...

void	log_update_exported_variables (const log_t &log)

Log - initialization of the redo log system.
dberr_t	log_sys_init (bool expect_no_files, lsn_t flushed_lsn, lsn_t &new_files_lsn)
	Initializes log_sys and finds existing redo log files, or creates a new set of redo log files. More...

dberr_t	log_start (log_t &log, lsn_t checkpoint_lsn, lsn_t start_lsn, bool allow_checkpoints=true)
	Starts the initialized redo log system using a provided checkpoint_lsn and current lsn. More...

void	log_sys_close ()
	Close the log system and free all the related memory. More...

void	log_write_ahead_resize (log_t &log, size_t new_size)
	Resizes the write ahead buffer in the redo log. More...

Log - the log position locking.
void	log_position_lock (log_t &log)
	Lock redo log. More...

void	log_position_unlock (log_t &log)
	Unlock the locked redo log. More...

void	log_position_collect_lsn_info (const log_t &log, lsn_t current_lsn, lsn_t checkpoint_lsn)
	Collect coordinates in the locked redo log. More...

Log - persisting the flags.
void	log_persist_disable (log_t &log)
	Disable redo logging and persist the information. More...

void	log_persist_enable (log_t &log)
	Enable redo logging and persist the information. More...

void	log_persist_crash_safe (log_t &log)
	Persist the information that it is safe to restart server. More...

void	log_persist_initialized (log_t &log)
	Marks the redo log files as belonging to the initialized data directory with initialized set of redo log files. More...

void	log_crash_safe_validate (log_t &log)
	Asserts that the log is not marked as crash-unsafe. More...

Log - the log threads and mutexes
#define	log_limits_mutex_enter(log) mutex_enter(&((log).limits_mutex))

#define	log_limits_mutex_exit(log) mutex_exit(&((log).limits_mutex))

#define	log_limits_mutex_own(log) mutex_own(&(log).limits_mutex)

void	log_background_threads_active_validate (const log_t &log)
	Validates that all the log background threads are active. More...

void	log_background_threads_inactive_validate ()
	Validates that all the log background threads are inactive. More...

void	log_start_background_threads (log_t &log)
	Starts all the log background threads. More...

void	log_stop_background_threads (log_t &log)
	Stops all the log background threads. More...

void	log_stop_background_threads_nowait (log_t &log)
	Marks the flag which tells log threads to stop and wakes them. More...

void	log_make_empty_and_stop_background_threads (log_t &log)
	Function similar to. More...

void	log_wake_threads (log_t &log)
	Wakes up all log threads which are alive. More...

Detailed Description

Redo log - the main header.

Basic types are defined inside log0types.h.

Constant values are defined inside log0constants.h, but that file should only be included by log0types.h.

The log_sys is defined in log0sys.h.

Functions related to the log buffer are declared in log0buf.h.

Functions related to the checkpoints are declared in log0chkp.h.

Functions related to the writer/flusher are declared in log0write.h.

Functions computing capacity of redo and related margins are declared in log0files_capacity.h.

Functions doing IO to log files and formatting log blocks are declared in log0files_io.h.

Macro Definition Documentation

◆ log_limits_mutex_enter

#define log_limits_mutex_enter ( log ) mutex_enter(&((log).limits_mutex))

◆ log_limits_mutex_exit

#define log_limits_mutex_exit ( log ) mutex_exit(&((log).limits_mutex))

◆ log_limits_mutex_own

#define log_limits_mutex_own ( log ) mutex_own(&(log).limits_mutex)

Function Documentation

◆ log_background_threads_active_validate()

void log_background_threads_active_validate ( const log_t & log )

Validates that all the log background threads are active.

Used only to assert, that the state is correct.

Parameters

[in] log redo log

◆ log_background_threads_inactive_validate()

void log_background_threads_inactive_validate ( )

Validates that all the log background threads are inactive.

Used only to assert, that the state is correct.

◆ log_crash_safe_validate()

void log_crash_safe_validate ( log_t & log )

Asserts that the log is not marked as crash-unsafe.

Parameters

[in,out] log redo log

◆ log_get_lsn()

lsn_t log_get_lsn ( const log_t & log )

inline

Gets the current lsn value.

This value points to the first non reserved data byte in the redo log. When next user thread reserves space in the redo log, it starts at this lsn.

If the last reservation finished exactly before footer of log block, this value points to the first byte after header of the next block.

Note: It is possible that the current lsn value does not fit free space in the log files or in the log buffer. In such case, user threads need to wait until the space becomes available.

Returns: current lsn

◆ log_get_sn()

static sn_t log_get_sn ( const log_t & log )

inlinestatic

Returns: consistent sn value for locked state

◆ log_is_data_lsn()

bool log_is_data_lsn ( lsn_t lsn )

inline

Validates a given lsn value.

Checks if the lsn value points to data bytes inside log block (not to some bytes in header/footer). It is used by assertions.

Returns: true if lsn points to data bytes within log block

◆ log_make_empty_and_stop_background_threads()

void log_make_empty_and_stop_background_threads ( log_t & log )

Function similar to.

See also: log_stop_background_threads() except that it stops all the log threads in such a way, that the redo log will be logically empty after the threads are stopped.

Note: It is caller responsibility to ensure that all threads other than the log_files_governor cannot produce new redo log records when this function is being called.

◆ log_persist_crash_safe()

void log_persist_crash_safe ( log_t & log )

Persist the information that it is safe to restart server.

Parameters

[in,out] log redo log

◆ log_persist_disable()

void log_persist_disable ( log_t & log )

Disable redo logging and persist the information.

Parameters

[in,out] log redo log

◆ log_persist_enable()

void log_persist_enable ( log_t & log )

Enable redo logging and persist the information.

Parameters

[in,out] log redo log

◆ log_persist_initialized()

void log_persist_initialized ( log_t & log )

Marks the redo log files as belonging to the initialized data directory with initialized set of redo log files.

Flushes the log_flags without the flag LOG_HEADER_FLAG_NOT_INITIALIZED to the newest redo log file.

Parameters

[in,out] log redo log

◆ log_position_collect_lsn_info()

void log_position_collect_lsn_info	(	const log_t &	log,
		lsn_t *	current_lsn,
		lsn_t *	checkpoint_lsn
	)

Collect coordinates in the locked redo log.

Parameters

[in]	log	locked redo log
[out]	current_lsn	stores current lsn there
[out]	checkpoint_lsn	stores checkpoint lsn there

◆ log_position_lock()

void log_position_lock ( log_t & log )

Lock redo log.

Both current lsn and checkpoint lsn will not change until the redo log is unlocked.

Parameters

[in,out] log redo log to lock

◆ log_position_unlock()

void log_position_unlock ( log_t & log )

Unlock the locked redo log.

Parameters

[in,out] log redo log to unlock

◆ log_print()

void log_print	(	const log_t &	log,
		FILE *	file
	)

Prints information about important lsn values used in the redo log, and some statistics about speed of writing and flushing of data.

Parameters

[in]	log	redo log for which print information
[out]	file	file where to print

◆ log_refresh_stats()

void log_refresh_stats ( log_t & log )

Refreshes the statistics used to print per-second averages in log_print().

Parameters

[in,out] log redo log

◆ log_start()

dberr_t log_start	(	log_t &	log,
		lsn_t	checkpoint_lsn,
		lsn_t	start_lsn,
		bool	allow_checkpoints = `true`
	)

Starts the initialized redo log system using a provided checkpoint_lsn and current lsn.

Block for current_lsn must be properly initialized in the log buffer prior to calling this function. Therefore a proper value of first_rec_group must be set for that block before log_start is called.

Parameters

[in,out]	log	redo log
[in]	checkpoint_lsn	checkpoint lsn
[in]	start_lsn	current lsn to start at
[in]	allow_checkpoints	true iff allows writing newer checkpoints

Returns: DB_SUCCESS or error

◆ log_start_background_threads()

void log_start_background_threads ( log_t & log )

Starts all the log background threads.

This can be called only, when the threads are inactive. This should never be called concurrently. This may not be called during read-only mode.

Parameters

[in,out] log redo log

◆ log_stop_background_threads()

void log_stop_background_threads ( log_t & log )

Stops all the log background threads.

This can be called only, when the threads are active. This should never be called concurrently. This may not be called in read-only mode. Note that is is impossible to start log background threads in such case.

Parameters

[in,out] log redo log

◆ log_stop_background_threads_nowait()

void log_stop_background_threads_nowait ( log_t & log )

Marks the flag which tells log threads to stop and wakes them.

Does not wait until they are stopped.

Parameters

[in,out] log redo log

◆ log_sys_close()

void log_sys_close ( )

Close the log system and free all the related memory.

◆ log_sys_init()

dberr_t log_sys_init	(	bool	expect_no_files,
		lsn_t	flushed_lsn,
		lsn_t &	new_files_lsn
	)

Initializes log_sys and finds existing redo log files, or creates a new set of redo log files.

New redo log files are created in following cases:

there are no existing redo log files in the log directory,
existing set of redo log files is not marked as fully initialized (flag LOG_HEADER_FLAG_NOT_INITIALIZED exists in the newest file).

After this call, the log_sys global variable is allocated and initialized. InnoDB might start recovery then.

Remarks: The redo log files are not resized in this function, because before resizing log files, InnoDB must run recovery and ensure log files are logically empty. The redo resize is currently the only scenario in which the initialized log_sys might become closed by log_sys_close() and then re-initialized by another call to log_sys_init().

Note

Note that the redo log system is NOT ready for user writes after this call is finished. The proper order of calls looks like this:

log_sys_init(),
log_start(),
log_start_background_threads() and this sequence is executed inside srv_start() in srv0start.cc (interleaved with remaining logic of the srv_start())

Note this function also verifies that REDO logs are in known format.

Parameters

[in]	expect_no_files	true means we should return DB_ERROR if log files are present in the directory before proceeding any further
[in]	flushed_lsn	lsn at which new redo log files might be started if they had to be created during this call; this should be lsn stored in the system tablespace header at offset FIL_PAGE_FILE_FLUSH_LSN if the data directory has been initialized;
[out]	new_files_lsn	updated to the lsn of the first checkpoint created in the new log files if new log files are created; else: 0

Returns: DB_SUCCESS or error

◆ log_translate_lsn_to_sn()

sn_t log_translate_lsn_to_sn ( lsn_t lsn )

inline

Calculates sn value for given lsn value.

See also: log_translate_sn_to_lsn

Parameters

[in] lsn lsn value

Returns: sn value for the provided lsn value

◆ log_translate_sn_to_lsn()

constexpr lsn_t log_translate_sn_to_lsn ( sn_t sn )

inlineconstexpr

Calculates lsn value for given sn value.

Sequence of sn values enumerate all data bytes in the redo log. Sequence of lsn values enumerate all data bytes and bytes used for headers and footers of all log blocks in the redo log. For every LOG_BLOCK_DATA_SIZE bytes of data we have OS_FILE_LOG_BLOCK_SIZE bytes in the redo log. NOTE that LOG_BLOCK_DATA_SIZE + LOG_BLOCK_HDR_SIZE + LOG_BLOCK_TRL_SIZE == OS_FILE_LOG_BLOCK_SIZE. The calculated lsn value will always point to some data byte (will be % OS_FILE_LOG_BLOCK_SIZE >= LOG_BLOCK_HDR_SIZE, and < OS_FILE_LOG_BLOCK_SIZE - LOG_BLOCK_TRL_SIZE).

Parameters

[in] sn sn value

Returns: lsn value for the provided sn value

◆ log_update_exported_variables()

void log_update_exported_variables ( const log_t & log )

◆ log_wait_for_space()

void log_wait_for_space	(	log_t &	log,
		sn_t	end_sn
	)

Waits until there is free space for range of sn values ending at the provided sn, in both the log buffer and in the log files.

Parameters

[in]	log	redo log
[in]	end_sn	end of the range of sn values

◆ log_wake_threads()

void log_wake_threads ( log_t & log )

Wakes up all log threads which are alive.

Parameters

[in,out] log redo log

◆ log_write_ahead_resize()

void log_write_ahead_resize	(	log_t &	log,
		size_t	new_size
	)

Resizes the write ahead buffer in the redo log.

Parameters

[in,out]	log	redo log
[in]	new_size	new size (in bytes)

Functions

Log - the log threads and mutexes

Detailed Description

Macro Definition Documentation

◆ log_limits_mutex_enter

◆ log_limits_mutex_exit

◆ log_limits_mutex_own

Function Documentation

◆ log_background_threads_active_validate()

◆ log_background_threads_inactive_validate()

◆ log_crash_safe_validate()

◆ log_get_lsn()

◆ log_get_sn()

◆ log_is_data_lsn()

◆ log_make_empty_and_stop_background_threads()

◆ log_persist_crash_safe()

◆ log_persist_disable()

◆ log_persist_enable()

◆ log_persist_initialized()

◆ log_position_collect_lsn_info()

◆ log_position_lock()

◆ log_position_unlock()

◆ log_print()

◆ log_refresh_stats()

◆ log_start()

◆ log_start_background_threads()

◆ log_stop_background_threads()

◆ log_stop_background_threads_nowait()

◆ log_sys_close()

◆ log_sys_init()

◆ log_translate_lsn_to_sn()

◆ log_translate_sn_to_lsn()

◆ log_update_exported_variables()

◆ log_wait_for_space()

◆ log_wake_threads()

◆ log_write_ahead_resize()