A distributed lock implementation based on SQLAlchemy
Project description
sqlalchemy-dlock
sqlalchemy-dlock
is a distributed-lock library based on Database and SQLAlchemy.
It currently supports below locks:
Database | Lock |
---|---|
MySQL | named lock |
PostgreSQL | advisory lock |
Install
pip install sqlalchemy-dlock
Usage
-
Work with SQLAlchemy
Connection
:from sqlalchemy import create_engine from sqlalchemy_dlock import create_sadlock key = 'user/001' engine = create_engine('postgresql://scott:tiger@127.0.0.1/') conn = engine.connect() # Create the D-Lock on the connection lock = create_sadlock(conn, key) # it's not lock when constructed assert not lock.locked # lock lock.acquire() assert lock.locked # un-lock lock.release() assert not lock.locked
-
with
statementfrom contextlib import closing from sqlalchemy import create_engine from sqlalchemy_dlock import create_sadlock key = 'user/001' engine = create_engine('postgresql://scott:tiger@127.0.0.1/') with engine.connect() as conn: # Create the D-Lock on the connection with create_sadlock(conn, key) as lock: # It's locked assert lock.locked # Auto un-locked assert not lock.locked # If do not want to be locked in `with`, a `closing` wrapper may help with closing(create_sadlock(conn, key)) as lock2: # It's NOT locked here !!! assert not lock2.locked # lock it now: lock2.acquire() assert lock2.locked # Auto un-locked assert not lock2.locked
-
Work with SQLAlchemy
ORM
Session
:from sqlalchemy import create_engine from sqlalchemy.orm import sessionmaker from sqlalchemy_dlock import create_sadlock key = 'user/001' engine = create_engine('postgresql://scott:tiger@127.0.0.1/') Session = sessionmaker(bind=engine) with Session() as session: with create_sadlock(session, key) as lock: assert lock.locked assert not lock.locked
-
Asynchronous I/O Support
💡 TIP
- SQLAlchemy
1.x
's asynchronous I/O: https://docs.sqlalchemy.org/14/orm/extensions/asyncio.html - SQLAlchemy
2.x
's asynchronous I/O: https://docs.sqlalchemy.org/20/orm/extensions/asyncio.html
from sqlalchemy.ext.asyncio import create_async_engine from sqlalchemy_dlock.asyncio import create_async_sadlock key = 'user/001' engine = create_async_engine('postgresql+asyncpg://scott:tiger@127.0.0.1/') async with engine.connect() as conn: async with create_async_sadlock(conn, key) as lock: assert lock.locked await lock.release() assert not lock.locked await lock.acquire() assert not lock.locked
ℹ️ NOTE
aiomysql, asyncpg and psycopg are tested asynchronous drivers.We can install it with asynchronous DB libraries:
pip install SQLAlchemy[asyncio] aiomysql sqlalchemy-dlock
or
pip install SQLAlchemy[asyncio] asyncpg sqlalchemy-dlock
- SQLAlchemy
Test
Following drivers are tested:
- MySQL:
- mysqlclient (synchronous)
- pymysql (synchronous)
- aiomysql (asynchronous)
- Postgres:
You can run unit-tests
-
on local environment:
-
Install the project in editable mode with
asyncio
optional dependencies, and libraries/drivers needed in test. A virtual environment (venv) is strongly advised:pip install -e .[asyncio] -r tests/requirements.txt
-
start up mysql and postgresql service
There is a docker compose file
db.docker-compose.yml
in project's top directory, which can be used to run mysql and postgresql develop environment conveniently:docker compose -f db.docker-compose.yml up
-
set environment variables
TEST_URLS
andTEST_ASYNC_URLS
for sync and async database connection url. Multiple connections separated by space.eg: (following values are also the defaults, and can be omitted)
TEST_URLS=mysql://test:test@127.0.0.1/test postgresql://postgres:test@127.0.0.1/ TEST_ASYNC_URLS=mysql+aiomysql://test:test@127.0.0.1/test postgresql+asyncpg://postgres:test@127.0.0.1/
ℹ️ NOTE
The test cases would load environment variables from dot-env filetests/.env
. -
run unit-test
python -m unittest
-
-
or on docker compose:
tests/docker-compose.yml
defines a Python and SQLAlchemy version matrix -- it combines Python3.8
to3.12
and SQLAlchemyv1
/v2
for test cases. We can run it by:cd tests docker-compose up --abort-on-container-exit
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