sqlalchemy-dlock 0.2a1

A distributed lock implementation based on SQLAlchemy

SQLAlchemy-DLock

Distributed lock based on Database and SQLAlchemy.

It currently supports locks of:

• MySQL: https://dev.mysql.com/doc/refman/8.0/en/locking-functions.html
• PostgreSQL: https://www.postgresql.org/docs/current/explicit-locking.html#ADVISORY-LOCKS

It's not stable and DO NOT use it in production.

Usages

Basic usage:

# ...
from sqlalchemy import create_engine
from sqlalchemy_dlock import sadlock

# ...

lock_key = 'user/001'

# ...

engine = create_engine('postgresql://scott:tiger@localhost/')

# ...

with engine.connect() as conn:
    with sadlock(conn, lock_key):
        pass
        # locked here!
        # ...
    pass
    # unlocked here!
    # ...
# ...

Work with SQLAlchemy's Session:

# ...
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy_dlock import sadlock

# ...

lock_key = 'user/001'

# ...

engine = create_engine('postgresql://scott:tiger@localhost/')
Session = sessionmaker(bind=engine)

# ...

session = Session()

# ...

with session.bind.connect() as conn:
    with sadlock(conn, lock_key):
        # locked here!
        # ...
        user = session.query('User').filter(id='001').one()
        user.password = 'new password'
        session.commit()
        # ...
    pass
    # unlocked here!
    # ...
# ...

CHANGELOG

v0.2a1

Date: 2021-03-08

• New:

  • Asynchronous IO Support by:

    • aiomysql for MySQL

      Connection URL is like: "mysql+aiomysql://user:password@host:3306/schema?charset=utf8mb4"

    • asyncpg for PostgreSQL

      Connection URL is like: "postgresql+asyncpg://user:password@host:5432/db"

    Read https://docs.sqlalchemy.org/en/14/orm/extensions/asyncio.html for details

v0.1.2

Date: 2021-01-26

Still an early version, not for production.

• Changes:
  • Arguments and it's default value of acquire now similar to stdlib's multiprossing.Lock, instead of Threading.Lock
  • MySQL lock now accepts float-point value as timeout
• Adds
  • Several new test cases
• Other
  • Many other small adjustment

v0.1.1

• A very early version, maybe not stable enough.
• Replace black2b with crc64-iso in PostgreSQL key convert function
• Only named arguments as extra parameters allowed in Lock's implementation class

AUTHORS

• Liu Xue Yan ([e-mail])