README#
sqlalchemy-dlock#
sqlalchemy-dlock
is a distributed-lock library based on Database and SQLAlchemy.
It currently supports below locks:
Database |
Lock |
---|---|
MySQL |
|
PostgreSQL |
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
đź’ˇ TIP
SQLAlchemy
1.x
’s asynchronous I/O: https://docs.sqlalchemy.org/14/orm/extensions/asyncio.htmlSQLAlchemy
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
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
How to build docs#
This documentation is made with Sphinx, be sure to install it’s dependencies:
pip install -r docs/requirements.txt
Ignore this step if requirements already installed.
(Optional) Re-generate API-Docs, if source tree changed:
sphinx-apidoc -o docs/apidocs -eMTf src
Build HTML documentation:
docs/make html
The built static web site is output to docs/_build/html
, we can serve it:
python -m http.server -d docs/_build/html
then open http://localhost:8000/ in a web browser.
Tip
Try another port if 8000
is already in use.
For example, to serve on port 8080
:
python -m http.server -d docs/_build/html 8080
See also
Python stdlib
’s http.server