Reading response after raising errors in hooks

[Bobronium]

Previous discussion

#2224

Problem

Currently response hooks are executed before response has been read. If any exception is raised during that time, https will call response.close(), preventing further read.

This doesn't play well with this pattern:

import logging

from httpx import Client, HTTPStatusError, Response

client = Client(event_hooks={"response": [Response.raise_for_status]})

try:
    client.get("https://google.com/404")
except HTTPStatusError as e:
    logging.exception(e.response.read())

Traceback (most recent call last):
  File "repro.py", line 8, in <module>
    client.get("https://google.com/404")
  File "httpx/_client.py", line 1039, in get
    return self.request(
  File "httpx/_client.py", line 815, in request
    return self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "httpx/_client.py", line 902, in send
    response = self._send_handling_auth(
  File "httpx/_client.py", line 930, in _send_handling_auth
    response = self._send_handling_redirects(
  File "httpx/_client.py", line 987, in _send_handling_redirects
    raise exc
  File "httpx/_client.py", line 970, in _send_handling_redirects
    hook(response)
  File "httpx/_models.py", line 736, in raise_for_status
    raise HTTPStatusError(message, request=request, response=self)
httpx.HTTPStatusError: Client error '404 Not Found' for url 'https://google.com/404'
For more information check: https://httpstatuses.com/404

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "repro.py", line 10, in <module>
    logging.exception(e.response.read())
  File "httpx/_models.py", line 792, in read
    self._content = b"".join(self.iter_bytes())
  File "httpx/_models.py", line 810, in iter_bytes
    for raw_bytes in self.iter_raw():
  File "httpx/_models.py", line 859, in iter_raw
    raise StreamClosed()
httpx.StreamClosed: Attempted to read or stream content, but the stream has been closed.

Workarounds

• Read response before raising for status in hook as suggested in Event hooks and raise_for_status #2224 (comment), but it's not plausible since hook doesn't have enough context to decide whether it's applicable to read response or not. It might be a huge streaming response which is not intended to stored in memory, for example.
• Instead of using hooks, subclass Client and redefine Client.send to raise for status after super().send has returned response

Solutions

• Include another type of hook that is executed only after response content has been read.