sqlalchemy_dlock.lock.mysql module

class sqlalchemy_dlock.lock.mysql.MysqlAsyncSadLock(connection_or_session, key, **kwargs)

Bases: MysqlSadLockMixin, BaseAsyncSadLock[str, AsyncConnection | AsyncSession | async_scoped_session]

Async IO version of MysqlSadLock

Parameters:

• key (Any) –

  MySQL named lock requires the key given by string.

  If key is not a str:

  • When bytes or alike, the constructor tries to decode it with default encoding:

    key = key.decode()
    

  • Otherwise the constructor force convert it to str:

    key = str(key)
    

  • Or you can specify a convert function to that argument

• convert –

  Custom function to covert key to required data type.

  Example

  def convert(value) -> str:
      # get a string key by `value`
      return the_string_covert_from_value
  

• connection_or_session (AsyncConnection | AsyncSession | async_scoped_session)

async do_acquire(block=True, timeout=None, *args, **kwargs)

Return type:

bool

Parameters:

• block (bool)

• timeout (float | int | None)

async do_release()

class sqlalchemy_dlock.lock.mysql.MysqlSadLock(connection_or_session, key, **kwargs)

Bases: MysqlSadLockMixin, BaseSadLock[str, Connection | Session | scoped_session]

A distributed lock implemented by MySQL named-lock

See also

https://dev.mysql.com/doc/refman/8.0/en/locking-functions.html

Caution

To MySQL locking function, it is even possible for a given session to acquire multiple locks for the same name. Other sessions cannot acquire a lock with that name until the acquiring session releases all its locks for the name. When perform multiple acquire() for a key on the same SQLAlchemy connection, latter acquire() will success immediately no wait and never block, it causes cascade lock instead!

Parameters:

• connection_or_session (Connection | Session | scoped_session) – BaseSadLock.connection_or_session

• key (Any) – BaseSadLock.key

• **kwargs – other named parameters pass to BaseSadLock and MysqlSadLockMixin

do_acquire(block=True, timeout=None, *args, **kwargs)

Return type:

bool

Parameters:

• block (bool)

• timeout (float | int | None)

do_release()

class sqlalchemy_dlock.lock.mysql.MysqlSadLockMixin(*, key, convert=None, **kwargs)

Bases: AbstractLockMixin[KTV, str]

A Mix-in class for MySQL named lock

Parameters:

• key (TypeVar(KTV, bound= Any)) –

  MySQL named lock requires the key given by string.

  If key is not a str:

  • When bytes or alike, the constructor tries to decode it with default encoding:

    key = key.decode()
    

  • Otherwise the constructor force convert it to str:

    key = str(key)
    

  • Or you can specify a convert function to that argument

• convert (Callable[[TypeVar(KTV, bound= Any)], str] | None) –

  Custom function to covert key to required data type.

  Example

  def convert(value) -> str:
      # get a string key by `value`
      return the_string_covert_from_value
  

classmethod convert(k)

The default key converter for MySQL named lock

Return type:

str

Parameters:

k (bytes | bytearray | memoryview | str | int | float)

get_actual_key()

The actual key used in MySQL named lock

Return type:

str