Recovers from last crashed binlog at server start. More...

#include <recovery.h>

Inheritance diagram for binlog::Binlog_recovery:

Public Member Functions
	Binlog_recovery (Binlog_file_reader &binlog_file_reader)
	Class constructor. More...

	~Binlog_recovery () override=default

bool	has_failures () const
	Retrieves whether or not the recovery process ended successfully. More...

bool	is_binlog_malformed () const
	Retrieves whether or not the binary log was correctly processed in full. More...

bool	has_engine_recovery_failed () const
	Retrieves whether or not the storage engines XA recovery process completed successfully. More...

std::string const &	get_failure_message () const
	Retrieves the textual representation of the encontered failure, if any. More...

Binlog_recovery &	recover ()
	Uses the provided binary log file reader to inspect the binary log and extract transaction information. More...

Public Member Functions inherited from binlog::Log_sanitizer
	Log_sanitizer ()
	Ctor. More...

virtual	~Log_sanitizer ()=default
	Dtor. More...

my_off_t	get_valid_pos () const
	Retrieves the position of the last binlog/relay log event that ended a transaction or position after the RLE/FDE/SE that comes from the source. More...

std::pair< my_off_t, bool >	get_valid_source_pos () const
	Retrieves the last valid source position of an event in read from the binary log / relay log file, which may be: More...

std::pair< std::string, bool >	get_valid_source_file () const
	Retrieves the updated name of the binlog source file. More...

bool	is_log_malformed () const
	Retrieves whether or not the log was correctly processed in full. More...

std::string const &	get_failure_message () const
	Retrieves the textual representation of the encontered failure, if any. More...

std::string	get_valid_file () const

bool	is_log_truncation_needed () const
	Checks whether a valid sanitized log file needs truncation of the last, partially written transaction or events that cannot be safely read. More...

bool	is_fatal_error () const
	Checks whether the fatal error occurred during log sanitization (OOM / decompression error which we cannot handle) More...

Protected Member Functions
PSI_memory_key &	get_memory_key () const override
	Function used to obtain memory key for derived classes. More...

Protected Member Functions inherited from binlog::Log_sanitizer
template<class Type_reader >
void	process_logs (Type_reader &reader)
	This function goes through the opened file and searches for a valid position in a binary log file. More...

template<class Type_reader >
void	process_logs (Type_reader &reader, const std::list< std::string > &list_of_files, MYSQL_BIN_LOG &log)
	This function goes iterates over the relay log files in the 'list_of_files' container, starting from the most recent one. More...

template<class Type_reader >
void	process_logs (Type_reader &reader, MYSQL_BIN_LOG &log)
	This function will obtain the list of relay log files using the object of MYSQL_BIN_LOG class and iterate over them to find the last valid position within a relay log file. More...

template<class Type_reader >
bool	process_one_log (Type_reader &reader, const std::string &filename)
	Reads and validates one log file. More...

void	process_query_event (Query_log_event const &ev)
	Invoked when a `Query_log_event` is read from the binary log file reader. More...

void	process_xid_event (Xid_log_event const &ev)
	Invoked when a `Xid_log_event` is read from the binary log file reader. More...

void	process_xa_prepare_event (XA_prepare_log_event const &ev)
	Invoked when a `XA_prepare_log_event` is read from the binary log file reader. More...

void	process_start ()
	Invoked when a `BEGIN` or an ‘XA START’ is found in a `Query_log_event`. More...

void	process_commit ()
	Invoked when a `COMMIT` is found in a `Query_log_event`. More...

void	process_rollback ()
	Invoked when a `ROLLBACK` is found in a `Query_log_event`. More...

void	process_atomic_ddl (Query_log_event const &ev)
	Invoked when a DDL is found in a `Query_log_event`. More...

void	process_xa_commit (std::string const &query)
	Invoked when an `XA COMMIT` is found in a `Query_log_event`. More...

void	process_xa_rollback (std::string const &query)
	Invoked when an `XA ROLLBACK` is found in a `Query_log_event`. More...

void	add_external_xid (std::string const &query, enum_ha_recover_xa_state state)
	Parses the provided string for an XID and adds it to the externally coordinated transactions map, along side the provided state. More...

Private Attributes
Binlog_file_reader &	m_reader
	File reader for the last available binary log file. More...

bool	m_no_engine_recovery {false}
	Whether or not the recovery in the storage engines failed. More...

Additional Inherited Members
Protected Attributes inherited from binlog::Log_sanitizer
bool	m_validation_started {true}
	Indicates whether validation has started. More...

my_off_t	m_valid_pos {0}
	Position of the last binlog/relay log event that ended a transaction. More...

my_off_t	m_valid_source_pos {0}
	Position of the last binlog event that ended a transaction (source position which corresponds to m_valid_pos) More...

std::string	m_valid_source_file {""}
	Currently processed binlog file set in case source rotation event is encountered. More...

std::string	m_valid_file {""}
	Last log file containing finished transaction. More...

bool	m_in_transaction {false}
	Whether or not the event being processed is within a transaction. More...

bool	m_is_malformed {false}
	Whether or not the binary log is malformed/corrupted or error occurred. More...

bool	m_fatal_error {false}
	Whether or not the binary log has a fatal error. More...

std::string	m_failure_message {""}
	Textual representation of the encountered failure. More...

MEM_ROOT	m_mem_root
	Memory pool to use for the XID lists. More...

Mem_root_allocator< my_xid >	m_set_alloc
	Memory pool allocator to use with the normal transaction list. More...

Mem_root_allocator< std::pair< const XID, XID_STATE::xa_states > >	m_map_alloc
	Memory pool allocator to use with the XA transaction list. More...

Xid_commit_list	m_internal_xids
	List of normal transactions fully written to the binary log. More...

Xa_state_list::list	m_external_xids
	List of XA transactions and states that appear in the binary log. More...

bool	m_is_log_truncation_needed {false}
	Information on whether log needs to be truncated, i.e. More...

bool	m_has_valid_pos {false}
	Indicator on whether a valid position has been found in the log file. More...

bool	m_has_valid_source_pos {false}
	Indicator on whether a valid source position has been found in the log file. More...

my_off_t	m_last_file_size {0}
	Last opened file size. More...

Detailed Description

Recovers from last crashed binlog at server start.

After a crash, storage engines may contain transactions that are prepared but not committed (in theory any engine, in practice InnoDB). This classe's methods use the binary log as the source of truth to determine which of these transactions should be committed and which should be rolled back.

The Binlog::recovery() method collects the following from the last available binary log:

the list of internally coordinated transactions (normal) that are completely written to the binary log.
the list of externally coordinated transactions (XA) that appear in the binary log, along the state those transactions are in.

The list of XIDs of all internally coordinated transactions that are completely written to the binary log is passed to the storage engines through the ha_recover function in the handler interface. This tells the storage engines to commit all prepared transactions that are in the set, and to roll back all prepared transactions that are not in the set.

The list of XIDs of all externally coordinated transactions that appear in the binary log, along with the state they are in, is passed to the storage engines through the ha_recover function in the handler interface. The storage engine will determine if the transaction is to be kept at PREPARE, is to be COMMITTED or ROLLED BACK, in accordance with: the state that is provided in the list; the internal storage engine state for the transaction.

Constructor & Destructor Documentation

◆ Binlog_recovery()

binlog::Binlog_recovery::Binlog_recovery ( Binlog_file_reader & binlog_file_reader )

Class constructor.

Parameters

binlog_file_reader The already instantiated and initialized file reader for the last available binary log file.

◆ ~Binlog_recovery()

binlog::Binlog_recovery::~Binlog_recovery ( )

overridedefault

Member Function Documentation

◆ get_failure_message()

std::string const & binlog::Binlog_recovery::get_failure_message ( ) const

Retrieves the textual representation of the encontered failure, if any.

Returns: the string containing the textual representation of the failure, an empty string otherwise.

◆ get_memory_key()

PSI_memory_key & binlog::Binlog_recovery::get_memory_key ( ) const

inlineoverrideprotectedvirtual

Function used to obtain memory key for derived classes.

Returns: Reference to a memory key

Implements binlog::Log_sanitizer.

◆ has_engine_recovery_failed()

bool binlog::Binlog_recovery::has_engine_recovery_failed ( ) const

Retrieves whether or not the storage engines XA recovery process completed successfully.

Returns: false if the storge engines completed the XA recovery process successfully, true otherwise.

◆ has_failures()

bool binlog::Binlog_recovery::has_failures ( ) const

Retrieves whether or not the recovery process ended successfully.

See also: Binlog_recovery::is_binlog_malformed(); Binlog_recovery::has_engine_recovery_failed()

Returns: true if the recovery process ended with errors, false otherwise.

◆ is_binlog_malformed()

bool binlog::Binlog_recovery::is_binlog_malformed ( ) const

Retrieves whether or not the binary log was correctly processed in full.

Returns: true if the binary log processing ended with errors, false otherwise.

◆ recover()

binlog::Binlog_recovery & binlog::Binlog_recovery::recover ( )

Uses the provided binary log file reader to inspect the binary log and extract transaction information.

The following is collected from the provided binlog file reader:

the list of internally coordinated transactions (normal) that are completely written to the binary log.
the list of externally coordinated transactions (XA) that appear in the binary log, along the state those transactions are in.

The list of XIDs of all internally coordinated transactions that are completely written to the binary log is passed to the storage engines through the ha_recover function in the handler interface. This tells the storage engines to commit all prepared transactions that are in the set, and to roll back all prepared transactions that are not in the set.

The list of XIDs of all externally coordinated transactions that appear in the binary log, along with the state they are in, is passed to the storage engines through the ha_recover function in the handler interface. The storage engine will determine if the transaction is to be kept at PREPARE, is to be COMMITTED or ROLLED BACK, in accordance with: the state that is provided in the list; the internal storage engine state for the transaction.

After recover() returns, has_failures() should be invoked to determine if the recover process ended successfully. Additionally, is_binlog_malformed() and has_engine_recovery_failed() can be invoked to determine the type of error that occurred.

Returns: This instance's reference, for chaining purposes.

Member Data Documentation

◆ m_no_engine_recovery

bool binlog::Binlog_recovery::m_no_engine_recovery {false}

private

Whether or not the recovery in the storage engines failed.

◆ m_reader

Binlog_file_reader& binlog::Binlog_recovery::m_reader