Fix compatibility with third-party sync-only middleware (#19)

.github/workflows/publish-develop-docs.yml

@@ -21,3 +21,5 @@ jobs:
                   git config user.email [email protected]
                   cd docs
                   mike deploy --push develop
+        concurrency:
+            group: publish-docs

.github/workflows/publish-release-docs.yml

@@ -21,3 +21,5 @@ jobs:
                   git config user.email [email protected]
                   cd docs
                   mike deploy --push --update-aliases ${{ github.event.release.name }} latest
+        concurrency:
+            group: publish-docs

CHANGELOG.md

@@ -32,26 +32,26 @@ Using the following categories, list your changes in this order:
 
 <!--changelog-start-->
 
-## [Unreleased]
+## [Unreleased](https://github.com/Archmonger/ServeStatic/compare/1.1.0...HEAD)
 
-- Nothing (yet)!
+### Fixed
+
+-   Fix compatibility with third-party sync only middleware
+    -   Django middleware now only runs in async mode to avoid clashing with Django's internal usage of `asgiref.AsyncToSync`
 
-## [1.1.0] - 2024-08-27
+## [1.1.0](https://github.com/Archmonger/ServeStatic/compare/1.0.0...1.1.0) - 2024-08-27
 
 ### Added
 
-- Files are now compressed within a thread pool to increase performance ([Upstream PR](https://github.com/evansd/whitenoise/pull/484))
+-   Files are now compressed within a thread pool to increase performance ([Upstream PR](https://github.com/evansd/whitenoise/pull/484))
 
 ### Fixed
 
-- Fix Django `StreamingHttpResponse must consume synchronous iterators` warning
-- Fix Django bug where file paths could fail to be followed on Windows ([Upstream PR](https://github.com/evansd/whitenoise/pull/474))
+-   Fix Django `StreamingHttpResponse must consume synchronous iterators` warning
+-   Fix Django bug where file paths could fail to be followed on Windows ([Upstream PR](https://github.com/evansd/whitenoise/pull/474))
 
-## [1.0.0] - 2024-05-08
+## [1.0.0](https://github.com/Archmonger/ServeStatic/releases/tag/1.0.0) - 2024-05-08
 
 ### Changed
 
-- Forked from [`whitenoise`](https://github.com/evansd/whitenoise) to add ASGI support.
-
-[Unreleased]: https://github.com/Archmonger/ServeStatic/compare/1.0.0...HEAD
-[1.0.0]: https://github.com/Archmonger/ServeStatic/releases/tag/1.0.0
+-   Forked from [`whitenoise`](https://github.com/evansd/whitenoise) to add ASGI support.

docs/src/dictionary.txt

@@ -30,3 +30,4 @@ bakhit
 sublicense
 middleware
 unhashed
+async

src/servestatic/middleware.py

@@ -50,7 +50,7 @@ def _set_streaming_content(self, value):
         if isinstance(value, AiofilesContextManager):
             value = AsyncFileIterator(value)
 
-        # Django < 4.2 doesn't support async file responses, so convert to sync
+        # Django < 4.2 doesn't support async file responses, so we convert to sync
         if django.VERSION < (4, 2) and hasattr(value, "__aiter__"):
             value = AsyncToSyncIterator(value)
 
@@ -75,12 +75,15 @@ class ServeStaticMiddleware(ServeStatic):
     """
 
     async_capable = True
-    sync_capable = True
+    sync_capable = False
 
     def __init__(self, get_response, settings=settings):
         self.get_response = get_response
-        if iscoroutinefunction(get_response):
-            markcoroutinefunction(self)
+        if not iscoroutinefunction(get_response):
+            raise ValueError(
+                "ServeStaticMiddleware requires an async compatible version of Django."
+            )
+        markcoroutinefunction(self)
 
         try:
             autorefresh: bool = settings.SERVESTATIC_AUTOREFRESH
@@ -159,32 +162,7 @@ def __init__(self, get_response, settings=settings):
         if self.use_finders and not self.autorefresh:
             self.add_files_from_finders()
 
-    def __call__(self, request):
-        if iscoroutinefunction(self.get_response):
-            return self.acall(request)
-
-        # Allow Django >= 3.2 to use async file responses when running via ASGI, even
-        # if Django forces this middleware to run synchronously
-        if django.VERSION >= (3, 2):
-            return asyncio.run(self.acall(request))
-
-        # Django version has no async uspport
-        return self.call(request)
-
-    def call(self, request):
-        """If the URL contains a static file, serve it. Otherwise, continue to the next
-        middleware."""
-        if self.autorefresh:
-            static_file = self.find_file(request.path_info)
-        else:
-            static_file = self.files.get(request.path_info)
-        if static_file is not None:
-            return self.serve(static_file, request)
-
-        # Run the next middleware in the stack
-        return self.get_response(request)
-
-    async def acall(self, request):
+    async def __call__(self, request):
         """If the URL contains a static file, serve it. Otherwise, continue to the next
         middleware."""
         if self.autorefresh and hasattr(asyncio, "to_thread"):
@@ -197,26 +175,7 @@ async def acall(self, request):
         if static_file is not None:
             return await self.aserve(static_file, request)
 
-        # Run the next middleware in the stack. Note that get_response can sometimes be sync if
-        # middleware was run in mixed sync-async mode
-        # https://docs.djangoproject.com/en/stable/topics/http/middleware/#asynchronous-support
-        if iscoroutinefunction(self.get_response):
-            return await self.get_response(request)
-        return self.get_response(request)
-
-    @staticmethod
-    def serve(static_file, request):
-        response = static_file.get_response(request.method, request.META)
-        status = int(response.status)
-        http_response = ServeStaticFileResponse(
-            response.file or (),
-            status=status,
-        )
-        # Remove default content-type
-        del http_response["content-type"]
-        for key, value in response.headers:
-            http_response[key] = value
-        return http_response
+        return await self.get_response(request)
 
     @staticmethod
     async def aserve(static_file, request):
@@ -334,8 +293,8 @@ class AsyncToSyncIterator:
     full compatibility with any environment.
 
     This converter must create a temporary event loop in a thread for two reasons:
-    1) Allows us to stream the iterator instead of buffering all contents in memory.
-    2) Allows the iterator to be used in environments where an event loop may not exist,
+    1. Allows us to stream the iterator instead of buffering all contents in memory.
+    2. Allows the iterator to be used in environments where an event loop may not exist,
     or may be closed unexpectedly.
 
     Currently used to add async file compatibility to Django WSGI and Django versions
@@ -361,3 +320,4 @@ def __iter__(self):
                     loop.run_until_complete, generator.__anext__()
                 ).result()
         loop.close()
+        thread_executor.shutdown(wait=False)

src/servestatic/responders.py

@@ -4,8 +4,7 @@
 import os
 import re
 import stat
-from email.utils import formatdate
-from email.utils import parsedate
+from email.utils import formatdate, parsedate
 from http import HTTPStatus
 from io import BufferedIOBase
 from time import mktime

tests/django_settings.py

@@ -4,8 +4,7 @@
 
 import django
 
-from .utils import AppServer
-from .utils import TEST_FILE_PATH
+from .utils import TEST_FILE_PATH, AppServer
 
 ALLOWED_HOSTS = ["*"]
 
@@ -29,7 +28,13 @@
 else:
     STATICFILES_STORAGE = "servestatic.storage.CompressedManifestStaticFilesStorage"
 
-MIDDLEWARE = ["servestatic.middleware.ServeStaticMiddleware"]
+MIDDLEWARE = [
+    "tests.middleware.sync_middleware_1",
+    "tests.middleware.async_middleware_1",
+    "servestatic.middleware.ServeStaticMiddleware",
+    "tests.middleware.sync_middleware_2",
+    "tests.middleware.async_middleware_2",
+]
 
 LOGGING = {
     "version": 1,

tests/middleware.py

@@ -0,0 +1,38 @@
+from asgiref.sync import iscoroutinefunction
+from django.utils.decorators import async_only_middleware, sync_only_middleware
+
+
+@sync_only_middleware
+def sync_middleware_1(get_response):
+    def middleware(request):
+        response = get_response(request)
+        return response
+
+    return middleware
+
+
+@async_only_middleware
+def async_middleware_1(get_response):
+    async def middleware(request):
+        response = await get_response(request)
+        return response
+
+    return middleware
+
+
+@sync_only_middleware
+def sync_middleware_2(get_response):
+    def middleware(request):
+        response = get_response(request)
+        return response
+
+    return middleware
+
+
+@async_only_middleware
+def async_middleware_2(get_response):
+    async def middleware(request):
+        response = await get_response(request)
+        return response
+
+    return middleware