Lahja

DISCLAIMER: This is alpha state software. Expect bugs.

Lahja is a generic event bus implementation written in Python 3.6+ that enables lightweight inter-process communication, based on non-blocking asynchronous IO

What is this for?

Lahja is tailored around one primary use case: enabling multi process Python applications to communicate via events between processes using non-blocking APIs based on asyncio or trio.

Key facts:

non-blocking APIs using asynchronous IO (asyncio / trio)
lightweight with zero dependencies
simple to use
easy multicasting of events (one event, many independent receivers)
easy event routing (e.g route event X only to certain receivers)
multiple consuming APIs to adapt to different use cases and styles

Developer Setup

If you would like to hack on lahja, please check out the Snake Charmers Tactical Manual for information on how we do:

Testing
Pull Requests
Code Style
Documentation

Development Environment Setup

You can set up your dev environment with:

git clone https://github.com/ethereum/lahja
cd lahja
virtualenv -p python3 venv
. venv/bin/activate
pip install -e .[dev]

Testing Setup

During development, you might like to have tests run on every file save.

Show flake8 errors on file change:

# Test flake8
when-changed -v -s -r -1 lahja/ tests/ -c "clear; flake8 lahja tests && echo 'flake8 success' || echo 'error'"

Run multi-process tests in one command, but without color:

# in the project root:
pytest --numprocesses=4 --looponfail --maxfail=1
# the same thing, succinctly:
pytest -n 4 -f --maxfail=1

Run in one thread, with color and desktop notifications:

cd venv
ptw --onfail "notify-send -t 5000 'Test failure ⚠⚠⚠⚠⚠' 'python 3 test on lahja failed'" ../tests ../lahja

Release setup

For Debian-like systems:

apt install pandoc

To release a new version:

make release bump=$$VERSION_PART_TO_BUMP$$

How to bumpversion

The version format for this repo is {major}.{minor}.{patch} for stable, and {major}.{minor}.{patch}-{stage}.{devnum} for unstable (stage can be alpha or beta).

To issue the next version in line, specify which part to bump, like make release bump=minor or make release bump=devnum.

If you are in a beta version, make release bump=stage will switch to a stable.

To issue an unstable version when the current version is stable, specify the new version explicitly, like make release bump="--new-version 4.0.0-alpha.1 devnum"