We eliminate some redundant checks.
We also consistently provide a `subscribers` field
in our stream data with `[]`, even if our users
can't access subscribers. We therefore bump
the API version and tweak the docs. (See further
down for a detailed justification of the change.)
Even though it is sometimes fine to have redundant code
that is defensive in nature, some upcoming changes are gonna
move subscriber-related logic out of build_stream_dict_for_sub
for certain codepaths as part of our effort to streamline
the payload for subscribers within page_params.
So we can't rely on the code that I removed here
inside of build_stream_dict_for_sub.
Anyway, it makes more sense to do these checks explicitly
in the validate function.
The code in build_stream_dict_for_sub was almost effectively
a noop, since the validation function was already preventing
us from getting subscriber info. The only difference it
made was sometimes converting `[]` to `None`, and then
subsequently omitting the subscribers field.
Neither ZT nor the webapp make any distinction between
`[]` or <missing key> for the `subscribers` data in
`page_params`.
The webapp has had this code for a long time (and now
equivalent code elsewhere in this PR):
if (!Object.prototype.hasOwnProperty.call(sub, "subscribers")) {
sub.subscribers = new LazySet([]);
}
The webapp calculates access based on booleans, anyway:
sub.can_access_subscribers =
page_params.is_admin || sub.subscribed ||
(!page_params.is_guest && !sub.invite_only);
And ZT would choke if `subscribers` were missing, except that
it never gets to the relevant code due to other checks:
def get_other_subscribers_in_stream(<snip>):
assert stream_id is not None or stream_name is not None
if stream_id:
assert self.is_user_subscribed_to_stream(stream_id)
return [sub
for sub in self.stream_dict[stream_id]['subscribers']
if sub != self.user_id]
else:
return [sub
for _, stream in self.stream_dict.items()
for sub in stream['subscribers']
if stream['name'] == stream_name
if sub != self.user_id]
You could make a semantic argument that we should prefer
<missing key> to `[]` when subscribers aren't even available, but
we have precedent from the way that `bulk_get_subscriber_user_ids`
has traditionally populated its result:
result: Dict[int, List[int]] =
{stream["id"]: [] for stream in stream_dicts}
If we changed `stream_dicts` to `target_stream_dicts` we
would faciliate a move toward `None`, but it would just cause
headaches for other server code as well as the frontends
(which, to reiterate, already prefer the empty array
for convenience).
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.
We no bulk up peer_add/peer_remove events by user if the
same user has subscribed to multiple streams (and just
that single user).
This mostly optimizes the new-user codepath, but the
algorithm is a bit more general in nature.
We now can send an implied matrix of user/stream tuples
for peer_add and peer_remove events.
The client code basically does this:
for stream_id in event['stream_ids']:
for user_id in event['user_ids']:
update_sub(stream_id, user_id)
We used to send individual events, which gets real
expensive when you are creating new streams. For
the case of copy-to-stream case, we should see
events go from U to 1, where U is the number of users
added.
Note that we don't yet fully optimize the potential
of this schema. For adding a new user with lots
of default streams, we still send S peer_add events.
And if you subscribe a bunch of users to a bunch of
private streams, we only go from U * S to S; we can't
optimize it down to one event easily.
All the fields of a stream's recipient object can
be inferred from the Stream, so we just make a local
object. Django will create a Message object without
checking that the child Recipient object has been
saved. If that behavior changes in some upgrade,
we should see some pretty obvious symptom, including
query counts changing.
Tweaked by tabbott to add a longer explanatory comment, and delete a
useless old comment.
This saves us a query for edge cases like when
you try to unsubscribe from a public stream
that you have already unsubscribed from.
But this is mostly to prep for upcoming
optimizations.
That class is an artifact of when Stream
didn't have recipient_id. Now it's simpler
to deal with stream subscriptions.
We also save a query during page load (and
other places where we get subscriber
info).
We already trust ids that are put on our queue
for deferred work. For example, see the code for
"mark_stream_messages_as_read_for_everyone"
We now pass stream_recipient_id when we queue
up work for do_mark_stream_messages_as_read.
This generally saves about 3 queries per
user when we unsubscribe them from a stream.
We get two speedups:
* The query to get existing subscribers only
gets the two fields we need. We no longer
need all the overhead of user_profile
and recipient data being returned in the
query.
* We avoid Django making extra hops to the
database to get user info.
We replace get_peer_user_ids_for_stream_change
with two bulk functions to get peers and/or
subscribers.
Note that we have three codepaths that care about
peers:
subscribing existing users:
we need to tell peers about new subscribers
we need to tell subscribed user about old subscribers
unsubscribing existing users:
we only need to tell peers who unsubscribed
subscribing new user:
we only need to tell peers about the new user
(right now we generate send_event
calls to tell the new user about existing
subscribers, but this is a waste
of effort that we will fix soon)
The two bulk functions are this:
bulk_get_subscriber_peer_info
bulk_get_peers
They have some overlap in the implementation,
but there are some nuanced differences that are
described in the comments.
Looking up peers/subscribers in bulk leads to some
nice optimizations.
We will save some memchached traffic if you are
subscribing to multiple public streams.
We will save a query in the remove-subscriber
case if you are only dealing with private streams.
We used to send occupy/vacate events when
either the first person entered a stream
or the last person exited.
It appears that our two main apps have never
looked at these events. Instead, it's
generally the case that clients handle
events related to stream creation/deactivation
and subscribe/unsubscribe.
Note that we removed the apply_events code
related to these events. This doesn't affect
the webapp, because the webapp doesn't care
about the "streams" field in do_events_register.
There is a theoretical situation where a
third party client could be the victim of
a race where the "streams" data includes
a stream where the last subscriber has left.
I suspect in most of those situations it
will be harmless, or possibly even helpful
to the extent that they'll learn about
streams that are in a "quasi" state where
they're activated but not occupied.
We could try to patch apply_event to
detect when subscriptions get added
or removed. Or we could just make the
"streams" piece of do_events_register
not care about occupy/vacate semantics.
I favor the latter, since it might
actually be what users what, and it will
also simplify the code and improve
performance.
This is a more thorough test of adding multiple
streams for multiple users, including streams
that users have already subscribed to.
The extra queries here are due to the fact
that we call `principal_to_user_profile` in
a loop in the view. So that's an example
of O(N) overhead. We may be able to bulk-fetch
these users eventually.
This is a pure extraction, except that I remove a
redundant check that `len(principals) > 0`. Whenever
that value is false, then `new_subscriptions` will
only have one possible entry, which is the current
user, and we skip that in the loop.
We no longer do O(N) queries to get existing streams.
This is a somewhat contrived use case--generally, we
are not trying to re-subscribe a user to several
streams. Still, we want to avoid this.
This commit also makes `test_bulk_subscribe_many`
do more work, and the change to the test helped
me discover this bug.
If a user asks to be subscribed to a stream
that they are already subscribed to, then
that stream won't be in new_stream_user_ids,
and we won't need to send an event for it.
This change makes that happen more automatically.
I think it's important that the callers understand
that bulk_add_subscriptions assumes all streams
are being created within a single realm, so I make
it an explicit parameter.
This may be overkill--I would also be happy if we
just included the assertions from this commit.
The query to finds and marks all unread UserMessages in the stream as read
can be quite expensive, so we'll move that work to the deferred_work
queue and split it into batches.
Fixes#15770.
The new Stream administrator role is allowed to manage a stream they
administer, including:
* Setting properties like name, description, privacy and post-policy.
* Removing subscribers
* Deactivating the stream
The access_stream_for_delete_or_update is modified and is used only
to get objects from database and further checks for administrative
rights is done by check_stream_access_for_delete_or_update.
We have also added a new exception class StreamAdministratorRequired.
This commit modifies the /streams endpoint so that the web-public
streams are included in the default list of streams that users
have access to.
This is part of PR #14638 that aims to allow guest users to
browse and subscribe themselves to web public streams.
Modifies filter_stream_authorization so that web-public streams are
added in the list of authorized streams that a guest user can
subscribe.
This commit is part of PR #14638 that aims to allow guest users
to browse and subscribe to web-public streams.
In this commit, we grant guest users access to stream history,
send message and common stream data of web-public streams.
This is part of PR #14638 that aims to allow guest users to
browse and subscribe to web-public streams.
This modification allows guest users to have access to web-public
streams subscribers, even if they aren't subscribed or never
subscribed to that stream.
This commit is part of PR #14638 that aims to allow guest users to
browser and subscribe to web-public streams.
Now, gather_subscriptions include web-public streams in the 3 sets
of streams that it returns, subscribed, unsubscribed and never
subscribed.
This is part of PR #14638 that aims to allow guest users to browse and
subscribe to web-public streams.
Added new Event Type in AbstractRealmAuditLog STREAM_CREATED.
Since we finally create streams in create_stream_if_needed function
in zerver/lib/streams.py so logged realm_audit there.
Passed acting_user when create_stream_if_needed or ensure_stream
function is called.
Added tests in test_audit_log.
Steve Howell
Mateusz Mandera
Anders Kaseorg
sahil839
Clara Dantas
Mohit Gupta
arpit551