This utilizes the generic `BaseNotes` we added for multipurpose
patching. With this migration as an example, we can further support
more types of notes to replace the monkey-patching approach we have used
throughout the codebase for type safety.
This is necessary to break the uncollectable reference cycle created
by our ‘request_notes.saved_response = json_response(…)’, Django’s
‘response._resource_closers.append(request.close)’, and Python’s
https://bugs.python.org/issue44680.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
This prevents a memory leak arising from Python’s inability to collect
a reference cycle from a WeakKeyDictionary value to its key
(https://bugs.python.org/issue44680).
Signed-off-by: Anders Kaseorg <anders@zulip.com>
This concludes the HttpRequest migration to eliminate arbitrary
attributes (except private ones that are belong to django) attached
to the request object during runtime and migrated them to a
separate data structure dedicated for the purpose of adding
information (so called notes) to a HttpRequest.
This includes the migration of fields that require trivial changes
to be migrated to be stored with ZulipRequestNotes.
Specifically _requestor_for_logs, _set_language, _query, error_format,
placeholder_open_graph_description, saveed_response, which were all
previously set on the HttpRequest object at some point. This migration
allows them to be typed.
We will no longer use the HttpRequest to store the rate limit data.
Using ZulipRequestNotes, we can access rate_limit and ratelimits_applied
with type hints support. We also save the process of initializing
ratelimits_applied by giving it a default value.
We create a class called ZulipRequestNotes as a new home to all the
additional attributes that we add to the Django HttpRequest object.
This allows mypy to do the typecheck and also enforces type safety.
Most of the attributes are added in the middleware, and thus it is
generally safe to assert that they are not None in a code path that
goes through the middleware. The caller is obligated to do manual
the type check otherwise.
This also resolves some cyclic dependencies that zerver.lib.request
have with zerver.lib.rate_limiter and zerver.tornado.handlers.
This ensures it is present for all requests; while that was already
essentially true via process_client being called from every standard
decorator, this allows middleware and other code to rely on this
having been set.
The Session middleware only adds `Vary: cookie` if it sees an access
to the from inside of it. Because we are effectively, from the Django
session middleware's point of view, returning the static content of
`request.saved_response` and never accessing the session, it does not
set `Vary: cookie` on longpoll requests.
Explicitly mark Tornado requests as varying by cookie.
The exception trace only goes from where the exception was thrown up
to where the `logging.exception` call is; any context as to where
_that_ was called from is lost, unless `stack_info` is passed as well.
Having the stack is particularly useful for Sentry exceptions, which
gain the full stack trace.
Add `stack_info=True` on all `logging.exception` calls with a
non-trivial stack; we omit `wsgi.py`. Adjusts tests to match.
Fixes#2665.
Regenerated by tabbott with `lint --fix` after a rebase and change in
parameters.
Note from tabbott: In a few cases, this converts technical debt in the
form of unsorted imports into different technical debt in the form of
our largest files having very long, ugly import sequences at the
start. I expect this change will increase pressure for us to split
those files, which isn't a bad thing.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
Generated by `pyupgrade --py3-plus --keep-percent-format` on all our
Python code except `zthumbor` and `zulip-ec2-configure-interfaces`,
followed by manual indentation fixes.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
Instead of trying to set the _requestor_for_logs attribute in all the
relevant places, we try to use request.user when possible (that will be
when it's a UserProfile or RemoteZulipServer as of now). In other
places, we set _requestor_for_logs to avoid manually editing the
request.user attribute, as it should mostly be left for Django to manage
it.
In places where we remove the "request._requestor_for_logs = ..." line,
it is clearly implied by the previous code (or the current surrounding
code) that request.user is of the correct type.
Since essentially the first use of Tornado in Zulip, we've been
maintaining our Tornado+Django system, AsyncDjangoHandler, with
several hundred lines of Django code copied into it.
The goal for that code was simple: We wanted a way to use our Django
middleware (for code sharing reasons) inside a Tornado process (since
we wanted to use Tornado for our async events system).
As part of the Django 2.2.x upgrade, I looked at upgrading this
implementation to be based off modern Django, and it's definitely
possible to do that:
* Continue forking load_middleware to save response middleware.
* Continue manually running the Django response middleware.
* Continue working out a hack involving copying all of _get_response
to change a couple lines allowing us our Tornado code to not
actually return the Django HttpResponse so we can long-poll. The
previous hack of returning None stopped being viable with the Django 2.2
MiddlewareMixin.__call__ implementation.
But I decided to take this opportunity to look at trying to avoid
copying material Django code, and there is a way to do it:
* Replace RespondAsynchronously with a response.asynchronous attribute
on the HttpResponse; this allows Django to run its normal plumbing
happily in a way that should be stable over time, and then we
proceed to discard the response inside the Tornado `get()` method to
implement long-polling. (Better yet might be raising an
exception?). This lets us eliminate maintaining a patched copy of
_get_response.
* Removing the @asynchronous decorator, which didn't add anything now
that we only have one API endpoint backend (with two frontend call
points) that could call into this. Combined with the last bullet,
this lets us remove a significant hack from our
never_cache_responses function.
* Calling the normal Django `get_response` method from zulip_finish
after creating a duplicate request to process, rather than writing
totally custom code to do that. This lets us eliminate maintaining
a patched copy of Django's load_middleware.
* Adding detailed comments explaining how this is supposed to work,
what problems we encounter, and how we solve various problems, which
is critical to being able to modify this code in the future.
A key advantage of these changes is that the exact same code should
work on Django 1.11, Django 2.2, and Django 3.x, because we're no
longer copying large blocks of core Django code and thus should be
much less vulnerable to refactors.
There may be a modest performance downside, in that we now run both
request and response middleware twice when longpolling (once for the
request we discard). We may be able to avoid the expensive part of
it, Zulip's own request/response middleware, with a bit of additional
custom code to save work for requests where we're planning to discard
the response. Profiling will be important to understanding what's
worth doing here.
This fixes a bug where our asynchronous requests were only copying the
Content-Type header (i.e. the one case where we're noticed) from the
Django HttpResponse. I'm not sure what the impact of this would be;
the rate-limiting headers rarely come up when breaking a long-polled
request. But it seems clearly an improvement to do this in a
consistent fashion.
Only the headers piece is a change; in Tornado
self.finish(x)
is equivalent to:
self.write(x)
self.finish()
Previous cleanups (mostly the removals of Python __future__ imports)
were done in a way that introduced leading newlines. Delete leading
newlines from all files, except static/assets/zulip-emoji/NOTICE,
which is a verbatim copy of the Apache 2.0 license.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
Previously, these timer accounting functions could be easily mistaken
for referring to starting/stopping the request. By adding timer to
the name, we make the code easier for the casual observer to read and
understand.
We're never going to add tests for this block, which is fundamentally
well-tested code from Django with a since line changed which is hard
to screw up (long-polling will not work at all without it). The hope
is to remove it entirely and replace it with a cleaner monkey-patch,
but until then, unit tests for it would be redundant.
Anders Kaseorg
PIG208
orientor
Alex Vandiver
Anders Kaseorg
Mateusz Mandera
Tim Abbott
Wyatt Hoodes
Vishnu Ks
neiljp (Neil Pilgrim)
rht