When MDL detects a lock wait timeout, it pushes an error into the statement diagnostics area. More...

Inheritance diagram for User_level_lock_wait_error_handler:

Public Member Functions
	User_level_lock_wait_error_handler ()

bool	got_timeout () const

bool	handle_condition (THD , uint sql_errno, const char , Sql_condition::enum_severity_level , const char ) override
	Handle a sql condition. More...

Private Attributes
bool	m_lock_wait_timeout

Additional Inherited Members
Protected Member Functions inherited from Internal_error_handler
	Internal_error_handler ()

Internal_error_handler *	prev_internal_handler () const

virtual	~Internal_error_handler ()=default

Detailed Description

When MDL detects a lock wait timeout, it pushes an error into the statement diagnostics area.

For GET_LOCK(), lock wait timeout is not an error, but a special return value (0). NULL is returned in case of error. Capture and suppress lock wait timeout. We also convert ER_LOCK_DEADLOCK error to ER_USER_LOCK_DEADLOCK error. The former means that implicit rollback of transaction has occurred which doesn't (and should not) happen when we get deadlock while waiting for user-level lock.

Constructor & Destructor Documentation

◆ User_level_lock_wait_error_handler()

User_level_lock_wait_error_handler::User_level_lock_wait_error_handler ( )

inline

Member Function Documentation

◆ got_timeout()

bool User_level_lock_wait_error_handler::got_timeout ( ) const

inline

◆ handle_condition()

bool User_level_lock_wait_error_handler::handle_condition	(	THD *	thd,
		uint	sql_errno,
		const char *	sqlstate,
		Sql_condition::enum_severity_level *	level,
		const char *	msg
	)

inlineoverridevirtual

Handle a sql condition.

This method can be implemented by a subclass to achieve any of the following:

mask a warning/error internally, prevent exposing it to the user,
mask a warning/error and throw another one instead. When this method returns true, the sql condition is considered 'handled', and will not be propagated to upper layers. It is the responsibility of the code installing an internal handler to then check for trapped conditions, and implement logic to recover from the anticipated conditions trapped during runtime.

This mechanism is similar to C++ try/throw/catch:

'try' correspond to THD::push_internal_handler(),
'throw' correspond to my_error(), which invokes my_message_sql(),
'catch' correspond to checking how/if an internal handler was invoked, before removing it from the exception stack with THD::pop_internal_handler().

Parameters

thd	the calling thread
sql_errno	the error number for the condition raised.
sqlstate	the SQLSTATE for the condition raised.
level	the severity level for the condition raised.
msg	the error message for the condition raised.

Returns: true if the condition is handled

Implements Internal_error_handler.

Member Data Documentation

◆ m_lock_wait_timeout

bool User_level_lock_wait_error_handler::m_lock_wait_timeout

private

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

sql/item_func.cc

Public Member Functions

Private Attributes

Additional Inherited Members