https://github.com/sethmlarson/pycon-async-sync-poster
An example project which demonstrates how to use some new tools to more easily maintain a codebase that supports both async and synchronous I/O and multiple async libraries.
https://github.com/sethmlarson/pycon-async-sync-poster
async asyncio curio pycon2020 python trio
Last synced: 3 months ago
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An example project which demonstrates how to use some new tools to more easily maintain a codebase that supports both async and synchronous I/O and multiple async libraries.
- Host: GitHub
- URL: https://github.com/sethmlarson/pycon-async-sync-poster
- Owner: sethmlarson
- License: cc0-1.0
- Created: 2020-04-25T20:48:39.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2020-05-06T17:17:05.000Z (over 5 years ago)
- Last Synced: 2025-04-09T15:11:20.458Z (6 months ago)
- Topics: async, asyncio, curio, pycon2020, python, trio
- Language: Python
- Homepage: https://sethmlarson.dev
- Size: 889 KB
- Stars: 22
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Designing Libraries for Async and Synchronous I/O
An example project which demonstrates how to use
some new tools to more easily maintain a codebase that supports
both async and synchronous I/O and multiple async libraries.
## Meet the Tools
- Supporting Sync and Async:
- [unasync](https://github.com/python-trio/unasync)
- Supporting multiple Async libraries:
- [sniffio](https://github.com/python-trio/sniffio)
- [anyio](https://github.com/agronholm/anyio)
The library itself is a massive contrived example that doesn't do anything useful.
The important part is seeing the different libraries and constructions
all working together!
## How the Project is Structured
There are three different categories of code that
go into creating a project that supports sync, asyncio, trio, etc:
#### Code that directly interacts with I/O APIs (sockets, threads, asyncio)
Code that directly interacts with individual APIs that are different across
the sync, asyncio, and Trio live under `backends/`. The function `get_backend()`
can either return a `SyncBackend` which uses a threadpool for parallelism and
`time.sleep` or return a flavor of `AsyncBackend` depending on which library
`sniffio` detects.
#### Code that needs to be async but doesn't directly interact with I/O APIs
This is where the bulk of your libraries public API code will probably live.
Typically you will write structural code here which call into your `Backend`
code written above.
You want to try to fit as much of your API code here as you can so you can
benefit from `unasync` generating the synchronous half automatically. When
writing this code you'll have to keep in mind what the resulting generated
code will look like though.
#### Code that doesn't have I/O
Code that doesn't need to touch I/O at all like enums, dataclasses, helpers, etc.
Also things like importing your `AsyncAPI` and `SyncAPI` to make them
accessible to users.
## Interesting Places to Look
- [`IS_ASYNC` detection of whether we're in `_async/` or `_sync/`](https://github.com/sethmlarson/pycon-async-sync-project/blob/master/sleepy/_async/client.py#L9)
- [Lazily load the backend so `AsyncSleeper` can be used in the global scope](https://github.com/sethmlarson/pycon-async-sync-project/blob/master/sleepy/_async/client.py#L38)
- [Backend Detection using Sniffio](https://github.com/sethmlarson/pycon-async-sync-project/blob/master/sleepy/backends/__init__.py#L13)
- [Unasync called within `setup.py` to generate `_sync/` code on dist build](https://github.com/sethmlarson/pycon-async-sync-project/blob/master/setup.py#L12)
## The Library in Action
```python
import asyncio
import sleepy
# === Asyncio ===
sleeper = sleepy.AsyncSleeper()
async def main_asyncio():
await sleeper.sleep_a_lot(3)
asyncio.run(main_asyncio())
# === Trio ===
# python -m pip install trio
import trio
sleeper = sleepy.AsyncSleeper()
async def main_trio():
await sleeper.sleep_a_lot(10)
trio.run(main_trio)
# === Sync ===
sleeper = sleepy.SyncSleeper()
def main_sync():
sleeper.sleep_a_lot(5)
main_sync()
```
## License
CC0-1.0