Support Trio with httpx #263
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The main limitation is that sniffing isn't supported, as the way it's currently designed (starting a task in the background and never collecting it) is not compatible with structured concurrency.
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| async def sniff(self, is_initial_sniff: bool = False) -> None: # type: ignore[override] | ||
| if sniffio.current_async_library() != "asyncio": |
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Wouldn't it be more appropriate here to show the error when current_async_library == "trio", since we know for a fact that sniffing does not work with it? We don't know if sniffing works or not with other async libraries, I assume. And also, this function raises an exception when it cannot recognize which library is in use. For backwards compatibility maybe we should allow the sniffing in such a case?
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What other async library?
- I haven't seen https://github.com/dabeaz/curio used anywhere, and it isn't making new releases anyway.
- Twisted isn't supported by sniffio or anyio
- trio-asyncio never really took off, and switching to
current_async_library == triowon't make any difference
I wouldn't see a different library making the same mistakes as asyncio, ie. allowing background tasks. Anyways, Trio has shown how hard it is for a different async library to take off, even with superior design, excellent docs, etc. So, for me, the condition makes sense: today, we only support sniffing with asyncio.
I find it interesting how this is exactly the discussion we're having in elastic/elasticsearch-py#3103 (comment).
| return # Call at most once! | ||
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| self._async_library = sniffio.current_async_library() | ||
| if self._async_library != "asyncio": |
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Same as above here. This is unlikely, but let's say that someone using "curio" was able to make sniffing work before. This would prevent them from using this feature. I think the check should be for == "trio", which is the one case that we know fails.
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Indeed, curio allows daemon tasks: https://curio.readthedocs.io/en/latest/reference.html#spawn. But I'm not aware of any HTTP client that supports curio. Since AnyIO dropped support for Curio, even asks does not support it. HTTPX does not support it.
tests/async_/test_async_transport.py Outdated
| "sniff_callback": sniff_callback, | ||
| } | ||
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| print(kwargs) |
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Is this print intended or left over from a debug session?
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The main limitation is that sniffing isn't supported, as the way it's currently designed (starting a task in the background and never collecting it) is not compatible with structured concurrency.