Redo log basic types. More...

#include <atomic>
#include <chrono>
#include <string>
#include "univ.i"
#include "os0file.h"
#include "ut0cpu_cache.h"
#include "log0constants.h"

Classes
struct	Log_files_context
	Configures path to the root directory, where redo subdirectory might be located (or redo log files if the ruleset is older). More...

struct	Log_file_header
	Meta data stored in log file header. More...

struct	Log_checkpoint_header
	Meta data stored in one of two checkpoint headers. More...

struct	Log_data_block_header
	Meta data stored in header of a log data block. More...

struct	Log_file_id_and_size
	Pair of: log file id and log file size (expressed in bytes). More...

struct	Log_file_id_and_header
	Pair of: log file id and log file header. More...

class	Log_file_handle
	Handle which allows to do reads / writes for the opened file. More...

struct	Log_file
	Meta information about single log file. More...

struct	Log_files_stats
	Runtime statistics related to redo log files management. More...

Macros
#define	LSN_PF UINT64PF
	Print format for lsn_t values, used in functions like printf. More...

Typedefs
typedef uint64_t	lsn_t
	Type used for all log sequence number storage and arithmetic. More...

typedef size_t	Log_file_id
	Log file id (0 for ib_redo0) More...

typedef uint32_t	Log_flags
	Log flags (stored in file header of log file). More...

typedef uint32_t	Log_uuid
	Number which tries to uniquely identify a created set of redo log files. More...

using	atomic_lsn_t = std::atomic< lsn_t >
	Alias for atomic based on lsn_t. More...

typedef uint64_t	sn_t
	Type used for sn values, which enumerate bytes of data stored in the log. More...

using	atomic_sn_t = std::atomic< sn_t >
	Alias for atomic based on sn_t. More...

typedef std::atomic< int64_t >	log_flushes_t
	Type used for counters in log_t: flushes_requested and flushes_expected. More...

typedef std::function< void(Log_file_id file_id, Log_file_type file_type, os_offset_t offset, os_offset_t size)>	Log_file_io_callback
	Callback called on each read or write operation on a redo log file. More...

typedef std::atomic< uint32_t()(const byte log_block)>	Log_checksum_algorithm_atomic_ptr
	Function used to calculate checksums of log blocks. More...

using	Log_clock = std::chrono::high_resolution_clock
	Clock used to measure time spent in redo log (e.g. More...

using	Log_clock_point = std::chrono::time_point< Log_clock >
	Time point defined by the Log_clock. More...

Enumerations
enum class	Log_checkpoint_header_no : uint32_t { HEADER_1 , HEADER_2 }
	Enumerates checkpoint headers in the redo log file. More...

enum class	Log_file_type { NORMAL , UNUSED }
	Type of redo log file. More...

enum class	Log_format : uint32_t { LEGACY = 0 , VERSION_5_7_9 = 1 , VERSION_8_0_1 = 2 , VERSION_8_0_3 = 3 , VERSION_8_0_19 = 4 , VERSION_8_0_28 = 5 , VERSION_8_0_30 = 6 , CURRENT = VERSION_8_0_30 }
	Supported redo log formats. More...

enum class	Log_files_ruleset { PRE_8_0_30 , CURRENT }
	Ruleset defining how redo log files are named, where they are stored, when they are created and what sizes could they have. More...

enum class	Log_resize_mode { NONE , RESIZING_DOWN }
	Direction of resize operation. More...

enum class	Log_file_access_mode { READ_WRITE , READ_ONLY , WRITE_ONLY }
	Type of access allowed for the opened redo log file. More...

Detailed Description

Redo log basic types.

Macro Definition Documentation

◆ LSN_PF

#define LSN_PF UINT64PF

Print format for lsn_t values, used in functions like printf.

Typedef Documentation

◆ atomic_lsn_t

using atomic_lsn_t = std::atomic<lsn_t>

Alias for atomic based on lsn_t.

◆ atomic_sn_t

using atomic_sn_t = std::atomic<sn_t>

Alias for atomic based on sn_t.

◆ Log_checksum_algorithm_atomic_ptr

typedef std::atomic<uint32_t (*)(const byte *log_block)> Log_checksum_algorithm_atomic_ptr

Function used to calculate checksums of log blocks.

◆ Log_clock

using Log_clock = std::chrono::high_resolution_clock

Clock used to measure time spent in redo log (e.g.

when flushing).

◆ Log_clock_point

using Log_clock_point = std::chrono::time_point<Log_clock>

Time point defined by the Log_clock.

◆ Log_file_id

typedef size_t Log_file_id

Log file id (0 for ib_redo0)

◆ Log_file_io_callback

typedef std::function<void(Log_file_id file_id, Log_file_type file_type, os_offset_t offset, os_offset_t size)> Log_file_io_callback

Callback called on each read or write operation on a redo log file.

Parameters

[in]	file_id	id of the redo log file (target of the IO operation)
[in]	file_type	type of the redo log file
[in]	offset	offset in the file, at which read or write operation is going to start (expressed in bytes and computed from the beginning of the file)
[in]	size	size of data that is going to be read or written in the IO operation

◆ Log_flags

typedef uint32_t Log_flags

Log flags (stored in file header of log file).

◆ log_flushes_t

typedef std::atomic<int64_t> log_flushes_t

Type used for counters in log_t: flushes_requested and flushes_expected.

They represent number of requests to flush the redo log to disk.

◆ Log_uuid

typedef uint32_t Log_uuid

Number which tries to uniquely identify a created set of redo log files.

Redo log files, which have different values of Log_uuid, most likely have been created for different directories and cannot be mixed. This way foreign redo files might be easily recognized. When that is the case, most likely something went wrong when copying files.

◆ lsn_t

typedef uint64_t lsn_t

Type used for all log sequence number storage and arithmetic.

◆ sn_t

typedef uint64_t sn_t

Type used for sn values, which enumerate bytes of data stored in the log.

Note that these values skip bytes of headers and footers of log blocks.

Enumeration Type Documentation

◆ Log_checkpoint_header_no

enum class Log_checkpoint_header_no : uint32_t

strong

Enumerates checkpoint headers in the redo log file.

Enumerator
HEADER_1	The first checkpoint header.
HEADER_2	The second checkpoint header.

◆ Log_file_access_mode

enum class Log_file_access_mode

strong

Type of access allowed for the opened redo log file.

Enumerator
READ_WRITE	The opened file can be both read and written.
READ_ONLY	The opened file can be only read.
WRITE_ONLY	The opened file can be only written.

◆ Log_file_type

enum class Log_file_type

strong

Type of redo log file.

Enumerator
NORMAL	Usual redo log file, most likely with important redo data.
UNUSED	Unused redo log file, might always be removed.

◆ Log_files_ruleset

enum class Log_files_ruleset

strong

Ruleset defining how redo log files are named, where they are stored, when they are created and what sizes could they have.

Enumerator

PRE_8_0_30

Redo log files were named ib_logfile0, ib_logfile1, ... ib_logfile99.

Redo log files were pre-created during startup and re-used after wrapping. Redo log files had the same file size and supported formats < VERSION_8_0_30. The non-initialized set of redo log files was denoted by existence of the ib_logfile101. The log files were located directly in the root directory (innodb_log_group_home_dir if specified; else: datadir).

CURRENT

Redo log files are named ib_redo0, ib_redo1, ... and no longer wrapped.

Redo log files are created on-demand during runtime and might have different sizes. Formats >= VERSION_8_0_30 are supported. The redo log files are located in innodb_redo subdirectory in the root directory - for example:

if innodb_log_group_home_dir = '/srv/my_db/logs', then redo files are in '/srv/my_db/logs/innodb_redo/',
if innodb_log_group_home_dir is not specified and datadir='/srv/my_db', then redo files are in '/srv/my_db/innodb_redo'.

◆ Log_format

enum class Log_format : uint32_t

strong

Supported redo log formats.

Stored in LOG_HEADER_FORMAT.

Enumerator
LEGACY	Unknown format of redo file.
VERSION_5_7_9	The MySQL 5.7.9 redo log format identifier. We can support recovery from this format if the redo log is clean (logically empty).
VERSION_8_0_1	Remove MLOG_FILE_NAME and MLOG_CHECKPOINT, introduce MLOG_FILE_OPEN redo log record.
VERSION_8_0_3	Allow checkpoint_lsn to point any data byte within redo log (before it had to point the beginning of a group of log records).
VERSION_8_0_19	Expand ulint compressed form.
VERSION_8_0_28	Row versioning header.
VERSION_8_0_30	Introduced with innodb_redo_log_capacity: write LSN does not re-enter file with checkpoint_lsn, epoch_no is checked strictly during recovery.
CURRENT	The redo log format identifier corresponding to the current format version.

◆ Log_resize_mode

enum class Log_resize_mode

strong

Direction of resize operation.

Enumerator
NONE	No pending resize.
RESIZING_DOWN	Resizing down.

Classes

Macros

Typedefs

Enumerations

Detailed Description

Macro Definition Documentation

◆ LSN_PF

Typedef Documentation

◆ atomic_lsn_t

◆ atomic_sn_t

◆ Log_checksum_algorithm_atomic_ptr

◆ Log_clock

◆ Log_clock_point

◆ Log_file_id

◆ Log_file_io_callback

◆ Log_flags

◆ log_flushes_t

◆ Log_uuid

◆ lsn_t

◆ sn_t

Enumeration Type Documentation

◆ Log_checkpoint_header_no

◆ Log_file_access_mode

◆ Log_file_type

◆ Log_files_ruleset

◆ Log_format

◆ Log_resize_mode