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.
Zulip has had a small use of WebSockets (specifically, for the code
path of sending messages, via the webapp only) since ~2013. We
originally added this use of WebSockets in the hope that the latency
benefits of doing so would allow us to avoid implementing a markdown
local echo; they were not. Further, HTTP/2 may have eliminated the
latency difference we hoped to exploit by using WebSockets in any
case.
While we’d originally imagined using WebSockets for other endpoints,
there was never a good justification for moving more components to the
WebSockets system.
This WebSockets code path had a lot of downsides/complexity,
including:
* The messy hack involving constructing an emulated request object to
hook into doing Django requests.
* The `message_senders` queue processor system, which increases RAM
needs and must be provisioned independently from the rest of the
server).
* A duplicate check_send_receive_time Nagios test specific to
WebSockets.
* The requirement for users to have their firewalls/NATs allow
WebSocket connections, and a setting to disable them for networks
where WebSockets don’t work.
* Dependencies on the SockJS family of libraries, which has at times
been poorly maintained, and periodically throws random JavaScript
exceptions in our production environments without a deep enough
traceback to effectively investigate.
* A total of about 1600 lines of our code related to the feature.
* Increased load on the Tornado system, especially around a Zulip
server restart, and especially for large installations like
zulipchat.com, resulting in extra delay before messages can be sent
again.
As detailed in
https://github.com/zulip/zulip/pull/12862#issuecomment-536152397, it
appears that removing WebSockets moderately increases the time it
takes for the `send_message` API query to return from the server, but
does not significantly change the time between when a message is sent
and when it is received by clients. We don’t understand the reason
for that change (suggesting the possibility of a measurement error),
and even if it is a real change, we consider that potential small
latency regression to be acceptable.
If we later want WebSockets, we’ll likely want to just use Django
Channels.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
zerver/openapi/python_examples.py:105: error: Argument 1 to "get_user_presence" of "Client" has incompatible type "str"; expected "Dict[str, Any]"
zerver/openapi/python_examples.py:563: error: Argument 1 to "add_reaction" of "Client" has incompatible type "Dict[str, object]"; expected "Dict[str, str]"
zerver/openapi/python_examples.py:576: error: Argument 1 to "remove_reaction" of "Client" has incompatible type "Dict[str, object]"; expected "Dict[str, str]"
zerver/worker/queue_processors.py:587: error: Argument "client" to "extract_query_without_mention" has incompatible type "EmbeddedBotHandler"; expected "ExternalBotHandler"
These were only missed because mypy daemon mode requires us to set
`follow_imports = skip` for the `zulip` package.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
tools/linter_lib/pyflakes.py:35: error: Argument 3 to "run_pyflakes" has incompatible type "List[Tuple[bytes, bytes]]"; expected "List[Tuple[str, str]]"
tools/linter_lib/custom_check.py:110: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:214: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:214: error: Argument "shebang_rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:502: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:502: error: Argument "shebang_rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:519: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:706: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:728: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:738: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:779: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
tools/linter_lib/custom_check.py:779: error: Argument "length_exclude" to "RuleList" has incompatible type "Set[str]"; expected "List[str]"
tools/linter_lib/custom_check.py:803: error: Argument "length_exclude" to "RuleList" has incompatible type "Set[str]"; expected "List[str]"
tools/linter_lib/custom_check.py:805: error: Unsupported operand types for + ("List[Rule]" and "List[Dict[str, Any]]")
tools/linter_lib/custom_check.py:819: error: Argument "rules" to "RuleList" has incompatible type "List[Dict[str, Any]]"; expected "List[Rule]"
These were missed the `zulint` package was missing PEP 561 type
annotation markers, and if it’d had them, mypy daemon mode would’ve
required us to set `follow_imports = skip` for it.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
Since pushing this down to specific modules in 8ca31773c, we've
had to do bookkeeping here for every new dependency we add, unless
we add stubs for it at the same time -- which we never have.
That'd be fine if we were burning down this list and on track to
eliminate it soon, but we aren't. So, go back to a global
acknowledgement that we have a lot of untyped dependencies. The
stubs we do have will work just the same, and we can keep adding
more for whatever libraries we choose to.
Also remove the ignore_missing_imports on it, which has no effect.
That setting only does anything when mypy doesn't know where to find
the module; follow_imports only does anything when it does know.
See upstream docs:
http://mypy.readthedocs.io/en/latest/config_file.html#per-module-flags
(I confirmed with `strace -f -efile` that the place mypy is finding
the `zulip` module is in fact in the virtualenv.)
This commit adds 'resize_gif()' function which extracts each frame,
resize it and coalesces them again to form the resized GIF while
preserving the duration of the GIF. I read some stackoverflow
answers all of which were referring to BiggleZX's script
(https://gist.github.com/BigglesZX/4016539) for working with animated
GIF. I modified the script to fit to our usecase and did some manual
testing but the function was failing for some specific GIFs and was not
preserving the duration of animation. So I went ahead and read about
GIF format itself as well as PIL's `GifImagePlugin` code and came up
with this simple function which gets the worked done in a much cleaner
way. I tested this function on a number of GIF images from giphy.com
and it resized all of them correctly.
Fixes: #9945.
Various pieces of our thumbor-based thumbnailing system were already
merged; this adds the remaining pieces required for it to work:
* a THUMBOR_URL Django setting that controls whether thumbor is
enabled on the Zulip server (and if so, where thumbor is hosted).
* Replaces the overly complicated prototype cryptography logic
* Adds a /thumbnail endpoint (supported both on web and mobile) for
accessing thumbnails in messages, designed to support hosting both
external URLs as well as uploaded files (and applying Zulip's
security model for access to thumbnails of uploaded files).
* Modifies bugdown to, when THUMBOR_URL is set, render images with the
`src` attribute pointing /thumbnail (to provide a small thumbnail
for the image), along with adding a "data-original" attribute that
can be used to access the "original/full" size version of the image.
There are a few things that don't work quite yet:
* The S3 backend support is incomplete and doesn't work yet.
* The error pages for unauthorized access are ugly.
* We might want to rename data-original and /thumbnail?size=original
to use some other name, like "full", that better reflects the fact
that we're potentially not serving the original image URL.
The main purpose of this commit is to demonstrate end-to-end that
our setup for type stubs works. I picked this library more or less
arbitrarily as one where the API surface we use is tiny, so that the
stub would be extra easy to write.
This will allow us to begin to add our own stubs for external
libraries. Writing stubs can be surprisingly little work to do, and
can have high leverage in keeping our type annotations high-quality.
This commit adds a view which will be used to process login requests,
adds an AuthenticationTokenForm so that we can use TextField widget for
tokens, and activates two factor authentication code path whenever user
tries to login.
The mypy daemon only supports error and skip. Choosing error
immediately surfaces when a file excluded from the build is
being imported, so that something can be done about it.
Commit fa18913b8 preserved the fix to the actual import, but added
back the `ignore_missing_imports` line that had shielded the
erroneous import. Remove that line again.
Anders Kaseorg
Tim Abbott
Wyatt Hoodes
neiljp (Neil Pilgrim)
Greg Price
Harshit Bansal
Rhea Parekh
Vishnu Ks
Aditya Bansal
Yago González
Umair Khan
Michael J. Sullivan
jkiely