Implement AsyncHTTPConnection.aclose

[ghost]

The base class implementation is empty and python will otherwise emit
a "ResourceWarning unclosed <socket.socket ...>" for the unclosed
sockets.

[lovelydinosaur]

Hiya!

So, httpcore is a low-level HTTP client, which means that you're required to ensure you're closing connections, eg. as documented in the quickstart...

    http_version, status_code, reason_phrase, headers, stream = await http.request(
        method=b'GET',
        url=(b'https', b'example.org', 443, b'/'),
    )

    try:
        body = b''.join(chunk async for chunk in stream)
    finally:
        await stream.close()

It's really important to use the try ... finally pattern if you're using httpcore at a low level.

Higher level clients like httpx will take care of this for you. Ie. httpx always manages the close for you, either with basic requests, or with .stream() using a context-managed API.

Having said that, we should forcibly close outstanding connections, yup, although this PR isn't quite the right approach. (I'm also surprised that it passed the tests - since the sync & async cases aren't in sync here.)

[lovelydinosaur]

Closing in favour of #98

[ghost]

I did run into this using httpx, which does call aclose on the AsyncHTTPConnection. I've used the async with httpx.AsyncClient() as client context manager stuff.

Should this have worked without the fix? Is there another bug in httpx?

[lovelydinosaur]

Ah gotcha. Anyways yup, without #98 we're not properly closing connections when the pool is cleaned up. We'll release a 0.9.1 version shortly. Thanks for having filed this!