Drop RuntimeError on closing a connection pool with active connections.

[lovelydinosaur]

Closes#564.

Closes#561 (The motivation given there becomes redundant. Errors will be raised against the connections themselves)

With this script...

example.py:

importanyioimporthttpcoreasyncdefworker(client, tg):
r=awaitclient.request('HEAD', 'https://google.com')
print(r)
tg.cancel_scope.cancel() # Cancel our other outstanding requestsasyncdefmain():
asyncwithhttpcore.AsyncConnectionPool() asclient, anyio.create_task_group() astg:
for_inrange(3):
tg.start_soon(worker, client, tg)
if__name__=="__main__":
anyio.run(main)

Before this change...

$ venv/bin/python ./example.py <Response [301]>
Traceback (most recent call last):
File "./example.py", line 18, in<module>
anyio.run(main)
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_core/_eventloop.py", line 70, in run
return asynclib.run(func, *args, **backend_options)
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_backends/_asyncio.py", line 292, in run
returnnative_run(wrapper(), debug=debug)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/runners.py", line 43, in run
return loop.run_until_complete(main)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/base_events.py", line 583, in run_until_complete
returnfuture.result()
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_backends/_asyncio.py", line 287, in wrapper
return await func(*args)
File "./example.py", line 14, in main
tg.start_soon(worker, client, tg)
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/connection_pool.py", line 326, in __aexit__
await self.aclose()
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/connection_pool.py", line 313, in aclose
f"The connection pool was closed while {requests_still_in_flight} "
RuntimeError: The connection pool was closed while 2 HTTP requests/responses were still in-flight.

After this change...

$ venv/bin/python ./example.py<Response [301]>

But, if we attempt close the connection pool and then later attempt to read from a connection, we will still get sensible behaviour...

example.py:

importanyioimporthttpcoreasyncdefworker(client, tg):
r=awaitclient.request('HEAD', 'https://google.com')
print(r)
awaitclient.aclose() # Yikes, lookout.asyncdefmain():
asyncwithhttpcore.AsyncConnectionPool() asclient, anyio.create_task_group() astg:
for_inrange(3):
tg.start_soon(worker, client, tg)
if__name__=="__main__":
anyio.run(main)

Output:

$ venv/bin/python ./example.py <Response [301]>
Traceback (most recent call last):
File "./example.py", line 17, in<module>
anyio.run(main)
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_core/_eventloop.py", line 70, in run
return asynclib.run(func, *args, **backend_options)
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_backends/_asyncio.py", line 292, in run
returnnative_run(wrapper(), debug=debug)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/runners.py", line 43, in run
return loop.run_until_complete(main)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/base_events.py", line 583, in run_until_complete
returnfuture.result()
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_backends/_asyncio.py", line 287, in wrapper
return await func(*args)
File "./example.py", line 13, in main
tg.start_soon(worker, client, tg)
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_backends/_asyncio.py", line 662, in __aexit__
raise exceptions[0]
File "/Users/tomchristie/Temp/venv/lib/python3.7/site-packages/anyio/_backends/_asyncio.py", line 702, in _run_wrapped_task
await coro
File "./example.py", line 6, in worker
r = await client.request('HEAD', 'https://google.com')
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/interfaces.py", line 43, in request
response = await self.handle_async_request(request)
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/connection_pool.py", line 253, in handle_async_request
raise exc
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/connection_pool.py", line 237, in handle_async_request
response = await connection.handle_async_request(request)
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/connection.py", line 90, in handle_async_request
return await self._connection.handle_async_request(request)
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/http11.py", line 112, in handle_async_request
raise exc
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/http11.py", line 91, in handle_async_request
) = await self._receive_response_headers(**kwargs)
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/http11.py", line 155, in _receive_response_headers
event = await self._receive_event(timeout=timeout)
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_async/http11.py", line 192, in _receive_event
self.READ_NUM_BYTES, timeout=timeout
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/backends/asyncio.py", line 36, inreadreturn b""
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/contextlib.py", line 130, in __exit__
self.gen.throw(type, value, traceback)
File "/Users/tomchristie/GitHub/encode/httpcore/httpcore/_exceptions.py", line 14, in map_exceptions
raise to_exc(exc)
httpcore.ReadError

[Kludex]

Closes #631 (Errors will be raised against the connections themselves)

This PR is #631, is that correct?

[lovelydinosaur]

This PR is #631, is that correct?

Ooops, updated.
Should have (and now does) read #561.

[lovelydinosaur]

Thanks @madkinsz 👍