ASGI is a standard for Python asynchronous web apps and servers to communicate with each other, and positioned as an asynchronous successor to WSGI. You can read more at https://asgi.readthedocs.io/en/latest/
This package includes ASGI base libraries, such as:
asgiref.syncasgiref.serverasgiref.wsgiThese allow you to wrap or decorate async or sync functions to call them from the other style (so you can call async functions from a synchronous thread, or vice-versa).
In particular:
The idea is to make it easier to call synchronous APIs from async code and asynchronous APIs from synchronous code so it's easier to transition code from one style to the other. In the case of Channels, we wrap the (synchronous) Django view system with SyncToAsync to allow it to run inside the (asynchronous) ASGI server.
Note that exactly what threads things run in is very specific, and aimed to keep maximum compatibility with old synchronous code. See "Synchronous code & Threads" below for a full explanation. By default, sync_to_async will run all synchronous code in the program in the same thread for safety reasons; you can disable this for more performance with @sync_to_async(thread_sensitive=False), but make sure that your code does not rely on anything bound to threads (like database connections) when you do.
This is a drop-in replacement for threading.local that works with both threads and asyncio Tasks. Even better, it will proxy values through from a task-local context to a thread-local context when you use sync_to_async to run things in a threadpool, and vice-versa for async_to_sync.
If you instead want true thread- and task-safety, you can set thread_critical on the Local object to ensure this instead.
Includes a StatelessServer class which provides all the hard work of writing a stateless server (as in, does not handle direct incoming sockets but instead consumes external streams or sockets to work out what is happening).
An example of such a server would be a chatbot server that connects out to a central chat server and provides a "connection scope" per user chatting to it. There's only one actual connection, but the server has to separate things into several scopes for easier writing of the code.
You can see an example of this being used in frequensgi.
Allows you to wrap a WSGI application so it appears as a valid ASGI application.
Simply wrap it around your WSGI application like so:
asgi_application = WsgiToAsgi(wsgi_application)
The WSGI application will be run in a synchronous threadpool, and the wrapped ASGI application will be one that accepts http class messages.
Please note that not all extended features of WSGI may be supported (such as file handles for incoming POST bodies).
asgiref requires Python 3.9 or higher.
Please refer to the main Channels contributing docs.
To run tests, make sure you have installed the tests extra with the package:
cd asgiref/ pip install -e .[tests] pytestBuilding the documentation
The documentation uses Sphinx:
cd asgiref/docs/ pip install sphinx
To build the docs, you can use the default tools:
sphinx-build -b html . _build/html # or `make html`, if you've got make set up cd _build/html python -m http.server
...or you can use sphinx-autobuild to run a server and rebuild/reload your documentation changes automatically:
pip install sphinx-autobuild sphinx-autobuild . _build/html
To release, first add details to CHANGELOG.txt and update the version number in asgiref/__init__.py.
Then, build and push the packages:
python -m build twine upload dist/* rm -r asgiref.egg-info distSynchronous code & threads
The asgiref.sync module provides two wrappers that let you go between asynchronous and synchronous code at will, while taking care of the rough edges for you.
Unfortunately, the rough edges are numerous, and the code has to work especially hard to keep things in the same thread as much as possible. Notably, the restrictions we are working with are:
SyncToAsync and marked with thread_sensitive should run in the same thread as each other (and if the outer layer of the program is synchronous, the main thread)AsyncToSync can't run things on that loop if it's blocked on synchronous code that is above you in the call stack.The first compromise you get to might be that thread_sensitive code should just run in the same thread and not spawn in a sub-thread, fulfilling the first restriction, but that immediately runs you into the second restriction.
The only real solution is to essentially have a variant of ThreadPoolExecutor that executes any thread_sensitive code on the outermost synchronous thread - either the main thread, or a single spawned subthread.
This means you now have two basic states:
AsyncToSync will run in a per-call event loop in arbitrary sub-threads, while all thread_sensitive code will run in the main thread.thread_sensitive synchronous code will run in a single shared sub-thread.Crucially, this means that in both cases there is a thread which is a shared resource that all thread_sensitive code must run on, and there is a chance that this thread is currently blocked on its own AsyncToSync call. Thus, AsyncToSync needs to act as an executor for thread code while it's blocking.
The CurrentThreadExecutor class provides this functionality; rather than simply waiting on a Future, you can call its run_until_future method and it will run submitted code until that Future is done. This means that code inside the call can then run code on your thread.
To report security issues, please contact security@djangoproject.com. For GPG signatures and more security process information, see https://docs.djangoproject.com/en/dev/internals/security/.
To report bugs or request new features, please open a new GitHub issue.
This repository is part of the Channels project. For the shepherd and maintenance team, please see the main Channels readme.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4