MySQL 8.3.0
Source Code Documentation
Locking_service_deadlock_error_handler Class Reference

We want to convert ER_LOCK_DEADLOCK error to ER_LOCK_SERVICE_DEADLOCK error. More...

Inheritance diagram for Locking_service_deadlock_error_handler:

Public Member Functions

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

Additional Inherited Members

- Protected Member Functions inherited from Internal_error_handler
 Internal_error_handler ()
Internal_error_handlerprev_internal_handler () const
virtual ~Internal_error_handler ()=default

Detailed Description

We want to convert ER_LOCK_DEADLOCK error to ER_LOCK_SERVICE_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 locking service locks.

We also want to convert ER_LOCK_WAIT_TIMEOUT as this error indicates that it helps to restart the transaction. This does not apply to locking service locks.

Member Function Documentation

◆ handle_condition()

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

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().
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.
true if the condition is handled

Implements Internal_error_handler.

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