Deadlock_notifier Class Reference

A static class for reporting notifications about deadlocks. More...

Public Member Functions
	Deadlock_notifier ()=delete

Static Public Member Functions
static void	notify (const ut::vector< const trx_t * > &trxs_on_cycle, const trx_t *victim_trx)
	Handles writing the information about found deadlock to the log files and caches it for future lock_latest_err_file() calls (for example used by SHOW ENGINE INNODB STATUS) More...

Static Private Member Functions
static bool	is_allowed_to_be_on_cycle (const lock_t *lock)
	Determines if a situation in which the lock takes part in a deadlock cycle is expected (as in: handled correctly) or not (say because it is on a DD table, for which there is no reason to expect a deadlock and we don't handle deadlocks correctly). More...
static void	print (const trx_t *trx, ulint max_query_len)
	Print transaction data to the deadlock file and possibly to stderr. More...
static void	start_print ()
	rewind(3) the file used for storing the latest detected deadlock and print a heading message to stderr if printing of all deadlocks to stderr is enabled. More...
static void	print (const lock_t *lock)
	Print lock data to the deadlock file and possibly to stderr. More...
static void	print (const char *msg)
	Print a message to the deadlock file and possibly to stderr. More...
static void	print_title (size_t pos_on_cycle, const char *title)
	Prints a numbered section title to the deadlock file and possibly to stderr. More...

Detailed Description

A static class for reporting notifications about deadlocks.

Constructor & Destructor Documentation

Deadlock_notifier()

Deadlock_notifier::Deadlock_notifier ( )

delete

Member Function Documentation

is_allowed_to_be_on_cycle()

bool Deadlock_notifier::is_allowed_to_be_on_cycle ( const lock_t *  lock )

staticprivate

Determines if a situation in which the lock takes part in a deadlock cycle is expected (as in: handled correctly) or not (say because it is on a DD table, for which there is no reason to expect a deadlock and we don't handle deadlocks correctly).

The purpose of the function is to use it in an assertion failing as soon as the deadlock is identified, to give developer a chance to investigate the root cause of the situation (without such assertion, the code might continue to run and either fail at later stage when the data useful for debugging is no longer on stack, or not fail at all, which is risky).

Parameters

[in]

lock

lock found in a deadlock cycle

Returns

true if we expect that this lock can take part in a deadlock cycle

notify()

void Deadlock_notifier::notify ( const ut::vector< const trx_t * > &  trxs_on_cycle, const trx_t *  victim_trx  )

static

Handles writing the information about found deadlock to the log files and caches it for future lock_latest_err_file() calls (for example used by SHOW ENGINE INNODB STATUS)

Parameters

[in]	trxs_on_cycle	trxs causing deadlock, i-th waits for i+1-th
[in]	victim_trx	the trx from trx_on_cycle which will be rolled back

print() [1/3]

void Deadlock_notifier::print ( const char *  msg )

staticprivate

Print a message to the deadlock file and possibly to stderr.

Parameters

msg	message to print

print() [2/3]

void Deadlock_notifier::print ( const lock_t *  lock )

staticprivate

Print lock data to the deadlock file and possibly to stderr.

Parameters

lock	record or table type lock

print() [3/3]

void Deadlock_notifier::print ( const trx_t *  trx, ulint  max_query_len  )

staticprivate

Print transaction data to the deadlock file and possibly to stderr.

Parameters

trx	transaction
max_query_len	max query length to print

print_title()

void Deadlock_notifier::print_title ( size_t  pos_on_cycle, const char *  title  )

staticprivate

Prints a numbered section title to the deadlock file and possibly to stderr.

Numbers do not have to be unique, as they are used to identify transactions on the cycle, and there are multiple sections per transaction.

Parameters

[in]	pos_on_cycle	The zero-based position of trx on deadlock cycle
[in]	title	The title of the section

start_print()

void Deadlock_notifier::start_print ( )

staticprivate

rewind(3) the file used for storing the latest detected deadlock and print a heading message to stderr if printing of all deadlocks to stderr is enabled.

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

• storage/innobase/lock/lock0lock.cc