An error handler which converts, if possible, ER_LOCK_DEADLOCK error that can occur when we are trying to acquire a metadata lock to a request for back-off and re-start of open_tables() process. More...

Inheritance diagram for MDL_deadlock_handler: Public Member Functions MDL_deadlock_handler ( Open_table_context *ot_ctx_arg) bool handle_condition ( THD *, uint sql_errno, const char *, Sql_condition::enum_severity_level *, const char *) override  Handle a sql condition. More...
Private Attributes Open_table_context * m_ot_ctx Open table context to be used for back-off request. More...
bool m_is_active Indicates that we are already in the process of handling ER_LOCK_DEADLOCK error. More...
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

Constructor & Destructor Documentation

◆ MDL_deadlock_handler()

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

thdthe calling thread sql_errnothe error number for the condition raised. sqlstatethe SQLSTATE for the condition raised. levelthe severity level for the condition raised. msgthe error message for the condition raised.

Returns

true if the condition is handled

Implements Internal_error_handler .

Member Data Documentation

◆ m_is_active