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>
Updates the message editing process to do a local 'echo'.
On slow connections, now there is visual confirmation of the edit,
similar to when sending messages. The contains_backend_only_syntax
logic and check are the same as there.
We showing "(SAVING)" until the edit is completed, and on successful
edit, the word "(EDITED)" appears. There's likely useful future work
to do on making the animation experience nicer.
Substantially rewritten by tabbott to better handle corner cases and
communicate more clearly about what's happening.
Fixes: #3530.
- Updated 260+ links from ".html" to ".md" to reduce the number of issues
reported about hyperlinks not working when viewing docs on Github.
- Removed temporary workaround that suppressed all warnings reported
by sphinx build for every link ending in ".html".
Details:
The recent upgrade to recommonmark==0.5.0 supports auto-converting
".md" links to ".html" so that the resulting HTML output is correct.
Notice that links pointing to a heading i.e. "../filename.html#heading",
were not updated because recommonmark does not auto-convert them.
These links do not generate build warnings and do not cause any issues.
However, there are about ~100 such links that might still get misreported
as broken links. This will be a follow-up issue.
Background:
docs: pip upgrade recommonmark and CommonMark #13013
docs: Allow .md links between doc pages #11719Fixes#11087.
There are two 'etc' words in the same line. This removes one of them.
Note from Tim: The old text was arguably correct, but removing it is definitely clearer.
Sphinx/ReadTheDocs supports automatically translating links written as
to `.md` files to point to the corresponding `.html` files, so this
migration does not change the resulting HTML output in ReadTheDocs.
But it does fix apparent broken links on GitHub.
This doesn't prevent people from reading the documentation on GitHub
(so doesn't mitigate the fact that some rtd-specific syntax does not
render properly on GH), but it will prevent us from getting erroneous
issues reported about the hyperlinks not working.
Fixes: #11087.
Anders Kaseorg
Jack Tiggleman
David Rosa
ruchit2801
Tim Abbott
Samuel Searles-Bryant