Accept async context managers for cleanup contexts (#11681) #11704
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…\nAdapt async context managers to behave like single-yield async iterators and add tests.
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aiohttp/web_app.py
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| # If the callback returned an async context manager (has | ||
| # __aenter__ and __aexit__), wrap it so it behaves like an | ||
| # async iterator that yields once. |
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Would it make more sense to make context managers our de facto default now? Surely then all we need to do for backwards compatibility is:
if not isinstance(ctx, AbstractAsyncContextManager):
ctx = asynccontextmanager(ctx)
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pushed a fix making it the default.
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No, I mean that the code should should be changed to use aenter/aexit instead of anext. Then we don't need the awkward _AsyncCMAsIterator class and much of the other code becomes much simpler.
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- fixed doc spelling issues - now uses AbstractAsyncContextManager
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What do these changes do?
Adapt async context managers to behave like single-yield async iterators.
1- Allow
app.cleanup_ctxcallbacks to return either:a single-yield async generator (existing behavior), or
an async context manager (e.g.
@contextlib.asynccontextmanager).2- Internally adapt async context managers with a small adapter so:
__aenter__runs at startup (equivalent to the generator yielding), and__aexit__runs at cleanup (equivalent to finishing the generator).3- Preserve previous cleanup/error aggregation semantics.
Are there changes in behavior for the user?
No breaking changes; this is fully backwards compatible.
contextlib.asynccontextmanagerinstances for cleanup contexts.Is it a substantial burden for the maintainers to support this?
No
Related issue number
Closes #11681
Checklist
CONTRIBUTORS.txtCHANGES/foldername it
<issue_or_pr_num>.<type>.rst(e.g.588.bugfix.rst)if you don't have an issue number, change it to the pull request
number after creating the PR
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.breaking: When something public is removed in a breaking way.Could be deprecated in an earlier release.
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.packaging: Notes for downstreams about unobvious side effectsand tooling. Changes in the test invocation considerations and
runtime assumptions.
.contrib: Stuff that affects the contributor experience. e.g.Running tests, building the docs, setting up the development
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