TC_LOG_MMAP Class Reference

#include <tc_log.h>

Inheritance diagram for TC_LOG_MMAP:

Classes
struct	PAGE

Public Types
enum	PAGE_STATE { PS_POOL , PS_ERROR , PS_DIRTY }
Public Types inherited from TC_LOG
enum	enum_result { RESULT_SUCCESS , RESULT_ABORTED , RESULT_INCONSISTENT }

Public Member Functions
	TC_LOG_MMAP ()
int	open (const char *opt_name) override
	Initialize and open the coordinator log. More...
void	close () override
	Close the transaction coordinator log and free any resources. More...
enum_result	commit (THD *thd, bool all) override
	Commit the transaction. More...
int	rollback (THD *thd, bool all) override
	Log a rollback record of the transaction to the transaction coordinator log. More...
int	prepare (THD *thd, bool all) override
	Log a prepare record of the transaction to the storage engines. More...
int	recover ()
uint	size () const
	Get the total amount of potentially usable slots for XIDs in TC log. More...
Public Member Functions inherited from TC_LOG
bool	using_heuristic_recover ()
	Perform heuristic recovery, if –tc-heuristic-recover was used. More...
	TC_LOG ()=default
virtual	~TC_LOG ()=default

Protected Member Functions
virtual int	do_msync_and_fsync (int fd_arg, void *addr, size_t len, int flags)

Private Member Functions
ulong	log_xid (my_xid xid)
	Record that transaction XID is committed on the persistent storage. More...
void	unlog (ulong cookie, my_xid xid)
	erase xid from the page, update page free space counters/pointers. More...
PAGE *	get_active_from_pool ()
	there is no active page, let's got one from the pool. More...
bool	sync ()
	Write the page data being synchronized to the disk. More...
void	overflow ()
ulong	store_xid_in_empty_slot (my_xid xid, PAGE *p, uchar *data_arg)
	Find empty slot in the page and write xid value there. More...
bool	wait_sync_completion (PAGE *p)
	Wait for until page data will be written to the disk. More...

Private Attributes
char	logname [FN_REFLEN]
File	fd
my_off_t	file_length
uint	npages
uint	inited
uchar *	data
PAGE *	pages
PAGE *	syncing
PAGE *	active
PAGE *	pool
PAGE **	pool_last_ptr
mysql_mutex_t	LOCK_tc
mysql_cond_t	COND_active
	Signalled when active PAGE is moved to syncing state, thus member "active" becomes 0. More...
mysql_cond_t	COND_pool
	Signalled when one more page becomes available in the pool which we might select as active. More...

Friends
class	TCLogMMapTest

Member Enumeration Documentation

PAGE_STATE

enum TC_LOG_MMAP::PAGE_STATE

Enumerator
PS_POOL
PS_ERROR
PS_DIRTY

Constructor & Destructor Documentation

TC_LOG_MMAP()

TC_LOG_MMAP::TC_LOG_MMAP ( )

inline

Member Function Documentation

close()

void TC_LOG_MMAP::close ( )

overridevirtual

Close the transaction coordinator log and free any resources.

Called during server shutdown.

Implements TC_LOG.

commit()

TC_LOG::enum_result TC_LOG_MMAP::commit ( THD *  thd, bool  all  )

overridevirtual

Commit the transaction.

Note

When the TC_LOG interface was changed, this function was added and uses the functions that were there with the old interface to implement the logic.

Implements TC_LOG.

do_msync_and_fsync()

virtual int TC_LOG_MMAP::do_msync_and_fsync ( int  fd_arg, void *  addr, size_t  len, int  flags  )

inlineprotectedvirtual

get_active_from_pool()

TC_LOG_MMAP::PAGE * TC_LOG_MMAP::get_active_from_pool ( )

private

there is no active page, let's got one from the pool.

Two strategies here:

1. take the first from the pool
2. if there're waiters - take the one with the most free space.

Returns

Pointer to qualifying page or NULL if no page in the pool can be made active.

log_xid()

ulong TC_LOG_MMAP::log_xid ( my_xid  xid )

private

Record that transaction XID is committed on the persistent storage.

This function is called in the middle of two-phase commit: First all resources prepare the transaction, then tc_log->log() is called, then all resources commit the transaction, then tc_log->unlog() is called.

All access to active page is serialized but it's not a problem, as we're assuming that fsync() will be a main bottleneck. That is, parallelizing writes to log pages we'll decrease number of threads waiting for a page, but then all these threads will be waiting for a fsync() anyway

If tc_log == MYSQL_BIN_LOG then tc_log writes transaction to binlog and records XID in a special Xid_log_event. If tc_log = TC_LOG_MMAP then xid is written in a special memory-mapped log.

Returns

"cookie", a number that will be passed as an argument to unlog() call. tc_log can define it any way it wants, and use for whatever purposes. TC_LOG_MMAP sets it to the position in memory where xid was logged to.

Return values

0

error

open()

int TC_LOG_MMAP::open ( const char *  opt_name )

overridevirtual

Initialize and open the coordinator log.

Do recovery if necessary. Called during server startup.

Parameters

opt_name

Name of logfile.

Return values

0	success
1	failed

Implements TC_LOG.

overflow()

void TC_LOG_MMAP::overflow ( )

private

prepare()

int TC_LOG_MMAP::prepare ( THD *  thd, bool  all  )

overridevirtual

Log a prepare record of the transaction to the storage engines.

Parameters

thd	Session to log transaction record for.
all	true if an explicit commit or an implicit commit for a statement, false if an internal commit of the statement.

Returns

Error code on failure, zero on success.

Implements TC_LOG.

recover()

int TC_LOG_MMAP::recover

(

)

rollback()

int TC_LOG_MMAP::rollback ( THD *  thd, bool  all  )

overridevirtual

Log a rollback record of the transaction to the transaction coordinator log.

When the function returns, the transaction have been aborted in the transaction coordinator log.

Parameters

thd	Session to log transaction record for.
all	true if an explicit commit or an implicit commit for a statement, false if an internal commit of the statement.

Returns

Error code on failure, zero on success.

Implements TC_LOG.

size()

uint TC_LOG_MMAP::size

(

)

const

Get the total amount of potentially usable slots for XIDs in TC log.

store_xid_in_empty_slot()

ulong TC_LOG_MMAP::store_xid_in_empty_slot ( my_xid  xid, PAGE *  p, uchar *  data_arg  )

inlineprivate

Find empty slot in the page and write xid value there.

Parameters

xid	value of xid to store in the page
p	pointer to the page where to store xid
data_arg	pointer to the top of the mapped to memory file to calculate offset value (cookie)

Returns

offset value from the top of the page where the xid was stored.

sync()

bool TC_LOG_MMAP::sync ( )

private

Write the page data being synchronized to the disk.

Return values

false	Success
true	Failure

unlog()

void TC_LOG_MMAP::unlog ( ulong  cookie, my_xid  xid  )

private

erase xid from the page, update page free space counters/pointers.

cookie points directly to the memory where xid was logged.

wait_sync_completion()

bool TC_LOG_MMAP::wait_sync_completion ( PAGE *  p )

inlineprivate

Wait for until page data will be written to the disk.

Parameters

p	pointer to the PAGE to store to the disk

Return values

false	Success
true	Failure

Friends And Related Function Documentation

TCLogMMapTest

friend class TCLogMMapTest

friend

Member Data Documentation

active

PAGE * TC_LOG_MMAP::active

private

COND_active

mysql_cond_t TC_LOG_MMAP::COND_active

private

Signalled when active PAGE is moved to syncing state, thus member "active" becomes 0.

COND_pool

mysql_cond_t TC_LOG_MMAP::COND_pool

private

Signalled when one more page becomes available in the pool which we might select as active.

data

uchar* TC_LOG_MMAP::data

private

fd

File TC_LOG_MMAP::fd

private

file_length

my_off_t TC_LOG_MMAP::file_length

private

inited

uint TC_LOG_MMAP::inited

private

LOCK_tc

mysql_mutex_t TC_LOG_MMAP::LOCK_tc

private

logname

char TC_LOG_MMAP::logname[FN_REFLEN]

private

npages

uint TC_LOG_MMAP::npages

private

pages

PAGE* TC_LOG_MMAP::pages

private

pool

PAGE * TC_LOG_MMAP::pool

private

pool_last_ptr

PAGE ** TC_LOG_MMAP::pool_last_ptr

private

syncing

PAGE * TC_LOG_MMAP::syncing

private

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The documentation for this class was generated from the following files:

• sql/tc_log.h
• sql/tc_log.cc