For 3000 messages and 400 users, this saved
about 30 seconds.
We only do two queries per batch of messages
now, and the algorithm is easier to analyze,
as it's just three nested loops.
Note that we are much more efficient about finding
active users here:
- we do one query per realm (instead of per-user)
- we pass the cutoff date to the database
- we get back just a list of distinct ids
This function is going away completely soon. It is
querying everybody's entire UserActivity history instead
of passing the cutoff date to the database!
The query counts increase here for somewhat
contrived reasons. The tests before this
commit reflected a successful trip to the
UserProfile cache, but that's not actually
realistic in practice.
The code we deleted here was no longer
doing anything.
Maybe the code was always dead, or maybe it
was written during a time when topics_by_diversity
and topics_by_length actually had different keys.
But now it's clearly cruft.
If we have 4 or more topics, then the code above
it would already have populated the list with 4
elements, and the `if num_convos < 4` condition
would evaluate to False.
And if we had 3 or fewer topics, then we would
have already put all possible topics into our
result, and the `topics_by_diversity[num_convos:4]`
slice would be empty.
It's possible that we should just have a simple
heuristic for topic hotness like `10*num_senders
+ messages`, so we don't have to maintain this
fiddly function, and we can just do something like
`topics_by_score[:4]`.
I now use sets for stream_ids in more of the digest
code.
As part of this I replaced exclude_subscription_modified_streams
with streams_recently_modified_for_user.
It's easier for the caller to just ask for ids
to delete from its callee than it is to pass
in a set/list to mutate.
The simpler boundary between the functions makes
the tests easier to write--you can see the
`filtered_streams` logic goes away in this diff.
I also make the tests a bit more thorough by using
combinations of Cordelia/Othello and Verona/Denmark
to try to find multiple possible flaws.
And I make the time intervals longer than 1s to
avoid false negatives from slow CI boxes.
If we have multiple users, this reduces the amount
of queries we need to do, because we get all
subscriptions for all users in a single query
to Subscription.
For the single-user case, we are introducing an
extra query hop, but the database is doing
roughly the same work, because we are just breaking
up this complex query into two hops:
messages =
select ... from message
where recipient__type_id in (
select stream_id from subscription
where ...
)
Now it's more like:
stream_ids =
select stream_id from subscription
where ...
messages =
select ... from message
where recipient__type_id in stream_ids
Note that we are not changing anything semantically
or algorithmically yet. The only overhead here
for the single-user case is boxing and unboxing
data into single-item dicts and lists.
The interfaces for callers in the view and the
queue processor remain the same for now.
This extraction will make a bit more sense when
we start doing bulk operations on a realm to
get digests, but even now, it encapsulates the
slightly complex way we cherry-pick the top 4
topics for a user.
This prep step is mostly for diff hygiene; the next
commit will make the code a bit nicer.
The original code here had the nice property that
most (but not all) of the DB work happened up
front in `handle_digest_email`, and none of the
DB work was delegated to the callers. But I
prefer the tradeoff of making the helpers a bit
more cohesive--let them get the data they need.
And we have query-count coverage in our tests,
so there's no real danger of having helpers
down in the stack insidiously doing a bunch of
extra DB hops.
In 709493cd75 (Feb 2017)
I added code to render_markdown that re-fetched the
sender of the message, to detect whether the message is
a bot.
It's better to just let the ORM fetch this. The
message object should already have sender.
The diff makes it look like we are saving round trips
to the database, which is true in some cases. For
the main message-send codepath, though, we are only
saving a trip to memcached, since the middleware
will have put our sender's user object into the
cache. The test_message_send test calls internally
to check_send_stream_message, so it was actually
hitting the database in render_markdown (prior to
my change).
Before this change we were clearing the cache on
every SQL usage.
The code to do this was added in February 2017
in 6db4879f9c.
Now we clear the cache just one time, but before
the action/request under test.
Tests that want to count queries with a warm
cache now specify keep_cache_warm=True. Those
tests were particularly flawed before this change.
In general, the old code both over-counted and
under-counted queries.
It under-counted SQL usage for requests that were
able to pull some data out of a warm cache before
they did any SQL. Typically this would have bypassed
the initial query to get UserProfile, so you
will see several off-by-one fixes.
The old code over-counted SQL usage to the extent
that it's a rather extreme assumption that during
an action itself, the entries that you put into
the cache will get thrown away. And that's essentially
what the prior code simulated.
Now, it's still bad if an action keeps hitting the
cache for no reason, but it's not as bad as hitting
the database. There doesn't appear to be any evidence
of us doing something silly like fetching the same
data from the cache in a loop, but there are
opportunities to prevent second or third round
trips to the cache for the same object, if we
can re-structure the code so that the same caller
doesn't have two callees get the same data.
Note that for invites, we have some cache hits
that are due to the nature of how we serialize
data to our queue processor--we generally just
serialize ids, and then re-fetch objects when
we pop them off the queue.
Steve asked me to remove this, since the tictactoe game was always
intended as a proof of concept. Now that we have poll and todo
widgets, the sample code for tictactoe has much less value.
We replace the content and type in test_widgets.py to maintain
coverage.
This reverts commit 564b199fe6, which
was part of #16308.
Escaping is either required or incorrect; it is never “defensive”.
This escaping is incorrect. lxml already escapes attributes during
serialization (any other behavior would be a serious bug), and
additional escaping just results in double escaping.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
Initally, when writing two or more quotes, having
a blank line in between them, merges those quotes.
This created confusion especially in "quote and reply".
This commit fixes such issues. Now two or more quotes
having a blank line in between them, will not get merged.
This change is correct both for usability and for improving our
compatibility with CommonMark.
Fixes#14379.
By registering a post_delete handler to clear appropriate caches in a
nicer way, we can get rid of the ugly flush-memcached call in the
delete_realm command.
Anders Kaseorg
Steve Howell
Mateusz Mandera
YashRE42
Aman Agrawal
akshatdalton
Mateusz Mandera