We have the `# frozen_string_literal: true` comment on all our
files. This means all string literals are frozen. There is no need
to call #freeze on any literals.
For files with `# frozen_string_literal: true`
```
puts %w{a b}[0].frozen?
=> true
puts "hi".frozen?
=> true
puts "a #{1} b".frozen?
=> true
puts ("a " + "b").frozen?
=> false
puts (-("a " + "b")).frozen?
=> true
```
For more details see: https://samsaffron.com/archive/2018/02/16/reducing-string-duplication-in-ruby
In some cases CTE caused pathologically bad query plans.
This optimises it so query runs by itself and caches for lifetime
of the topic query object.
This lightweight caching is done cause topic query will often
execute two queries (one for pinned and one for non pinned)
This feature adds the ability to define synonyms for tags, and the ability to merge one tag into another while keeping it as a synonym. For example, tags named "js" and "java-script" can be synonyms of "javascript". When searching and creating topics using synonyms, they will be mapped to the base tag.
Along with this change is a new UI found on each tag's page (for example, `/tags/javascript`) where more information about the tag can be shown. It will list the synonyms, which categories it's restricted to (if any), and which tag groups it belongs to (if tag group names are public on the `/tags` page by enabling the "tags listed by group" setting). Staff users will be able to manage tags in this UI, merge tags, and add/remove synonyms.
Instead of enabling `suppress_from_latest` setting on many categories now we can enable `mute_all_categories_by_default` site setting. Then users should opt-in to categories for them to appear in the latest and categories pages.
Also:
Move includes call higher which makes it possible to run all of the
intermediate queries for easier debugging.
Add tests for TagsController with categories in the path.
If we are searching for categories by their slugs, it doesn't make sense
to include subcategories since a slug, by itself, does not necessarily
uniquely identify a subcategory.
Similarly, the empty string as a slug is not a good category identifier.
Doing .pluck(:column).first is a very common pattern in Discourse and in
most cases, a limit cause isn't being added. Instead of adding a limit
clause to all these callsites, this commit adds two new methods to
ActiveRecord::Relation:
pluck_first, equivalent to limit(1).pluck(*columns).first
and pluck_first! which, like other finder methods, raises an exception
when no record is found
Zeitwerk simplifies working with dependencies in dev and makes it easier reloading class chains.
We no longer need to use Rails "require_dependency" anywhere and instead can just use standard
Ruby patterns to require files.
This is a far reaching change and we expect some followups here.
In some very specific cases (large sites) shared drafts can introduce a
performance hit due to the mechanism used to filter out topics
This avoids the entire process when shared drafts are not enabled
* Revert "Revert "FEATURE: Publish read state on group messages. (#7989) [Undo revert] (#8024)""
This reverts commit 36425eb9f0.
* Fix: Show who read only if the attribute is enabled
* PERF: Precalculate the last post readed by a group member
* Use book-reader icon instear of far-eye
* FIX: update topic groups correctly
* DEV: Tidy up read indicator update on write
* Reenable: "FEATURE: Publish read state on group messages. (#7989)"
This reverts commit 67f5cc1ce8.
* FIX: Read indicator only appears when the group setting is enabled
* Enable or disable read state based on group attribute
* When read state needs to be published, the minimum unread count is calculated in the topic query. This way, we can know if someone reads the last post
* The option can be enabled/disabled from the UI
* The read indicator will live-updated using message bus
* Show read indicator on every post
* The read indicator now shows read count and can be expanded to see user avatars
* Read count gets updated everytime someone reads a message
* Simplify topic-list read indicator logic
* Unsubscribe from message bus on willDestroyElement, removed unnecesarry values from post-menu, and added a comment to explain where does minimum_unread_count comes from
During profiling looking up topic users popped up as a hot path, this
change more than halved the amount of work it does
It reduces object allocations and method calls and avoids repeate translation
of common terms
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
We had quite a few cases in core where inputs are being mutated as a side
effect of calling a method.
This handles all the cases where specs caught this.
Mutating inputs makes code harder to reason about. Eg:
```
frog = "frog"
jump(frog)
puts frog
"fly" # ?????
```
This commit is part of a followup commit that adds # frozen_string_literal
to all our specs.
This new site setting determines the maximum age of unread topics in
suggested. By default if you have any unread topics older than 90 days
they will be omitted from suggested.
This change was added for 2 reasons:
1. A performance safeguard, some users tend to collect a huge amount of
read state so it becomes super expensive to find unread
2. People who collect a large amount of unread are much more interested in
recent unread topics vs ancient unread topics, this makes suggested more
relevant
Also, this is a minor speed up for tests cause 3 expensive tests became 1.
Previously we tried using a sub-query which has some terrible performance
implications, by adding 1 extra query we can eliminate the PG issue
A join to user_stats also is prone to the same slowdown
This optimisation avoids large scans joining the topics table with the
topic_users table.
Previously when a user carried a lot of read state we would have to join
the entire read state with the topics table. This operation would slow down
home page and every topic page. The more read state you accumulated the
larger the impact.
The optimisation helps people who clean up unread, however if you carry
unread from years ago it will only have minimal impact.
Historically due to https://meta.discourse.org/t/why-is-discourse-so-slow-on-android/8823
we decreased page sizes of both home page and topic page on android by half.
This was done on the server side and as a side effect and caused page sizes on android
to mismatch between Android and non Android.
Unfortunately about a year ago googlebot started pretending it is Android,
this cause Google to start indexing pages as what android would see. So
it saw double the amount of pages in the index as what exists on desktop.
This in turn caused double the amount of indexing work and a large amount
of broken links on long topics.
This fix removes all special behavior which is no longer needed due to
other performance work in Discourse including raw handlebars on home page
and virtual dom on topic pages.
I tested we do not need this on Blu Advance 5.0 it has 1.3 GHZ mediatec mt6580
This phone retails for around $50 USD.
If we decide long term that we want any hacks like this we will shift them
to the client side. It can just hold data in memory without rendering.
Previously the related PMs were last meaning you would have to work through
all unread to see them.
Also amends it so it either asks for related by group OR user not both.
- By default, behaviour is not changed: tags are made lowercase upon creation and edit.
- If force_lowercase_tags is disabled, then mixed case tags are allowed.
- Tags must remain case-insensitively unique. This is enforced by ActiveRecord and Postgres.
- A migration is added to provide a `UNIQUE` index on `lower(name)`. Migration includes a safety to correct any current tags that do not meet the criteria.
- A `where_name` scope is added to `models/tag.rb`, to allow easy case-insensitive lookups. This is used instead of `Tag.where(name: "blah")`.
- URLs remain lowercase. Mixed case URLs are functional, but have the lowercase equivalent as the canonical.
This feature can be enabled by choosing a destination for the
`shared drafts category` site setting.
* Staff members can create shared drafts, choosing a destination
category for the topic when it is published.
* Shared Drafts can be viewed in their category, or above the
topic list for the destination category where it will end up.
* When the shared draft is ready, it can be published to the
appropriate category by clicking a button on the topic view.
* When published, Drafts change their timestamps to the current
time, and any edits to the original post are removed.
```
EXPLAIN ANALYZE SELECT "topics".* FROM "topics"
LEFT JOIN topic_users tu ON topics.id = tu.topic_id AND tu.user_id =
13455
WHERE ("topics"."deleted_at" IS NULL)
AND (topics.archetype = 'private_message')
AND (
topics.id IN (
SELECT topic_id
FROM topic_allowed_groups tg
JOIN group_users gu ON gu.user_id = 13455 AND gu.group_id =
tg.group_id
WHERE gu.group_id IN (47)
)
)
AND (
topics.id IN (
SELECT ta.topic_id
FROM topic_allowed_users ta
WHERE ta.user_id IN (32852,-10)
)
OR
topics.id IN (
SELECT tg.topic_id
FROM topic_allowed_groups tg
WHERE tg.group_id IN (-10)
)
)
AND (topics.id NOT IN (69933,69995,69988,69984,69968,69973,69971,69952))
AND "topics"."visible" = 't'
ORDER BY topics.bumped_at DESC
LIMIT 3;
```
Planning time: 1.277 ms
Execution time: 71.577 ms
```
EXPLAIN ANALYZE SELECT "topics".* FROM "topics"
LEFT JOIN topic_users tu ON topics.id = tu.topic_id AND tu.user_id =
13455
LEFT JOIN (
SELECT * FROM topic_allowed_groups _tg
LEFT JOIN group_users gu
ON gu.user_id = 13455
AND gu.group_id = _tg.group_id
AND gu.group_id IN (47)
) tg ON topics.id = tg.topic_id
LEFT JOIN topic_allowed_users ta2 ON topics.id = ta2.topic_id AND
ta2.user_id IN (32852)
WHERE ("topics"."deleted_at" IS NULL)
AND (topics.archetype = 'private_message')
AND (tg.topic_id IS NOT NULL)
AND (ta2.topic_id IS NOT NULL)
AND (topics.id NOT IN (69933,69995,69988,69984,69968,69973,69971,69952))
AND "topics"."visible" = 't'
ORDER BY topics.bumped_at DESC
LIMIT 3;
```
Planning time: 1.191 ms
Execution time: 0.129 ms
```
EXPLAIN ANALYZE SELECT "topics".*
FROM "topics" LEFT JOIN topic_users tu ON topics.id = tu.topic_id AND
tu.user_id = 13455
WHERE ("topics"."deleted_at" IS NULL)
AND (topics.archetype = 'private_message')
AND (
topics.id IN (
SELECT topic_id
FROM topic_allowed_users
WHERE user_id = 13455
)
)
AND (
topics.id IN (
SELECT ta.topic_id
FROM topic_allowed_users ta
WHERE ta.user_id IN (2,1995,8307,17621,22980,-10)
)
OR
topics.id IN (
SELECT tg.topic_id
FROM topic_allowed_groups tg
WHERE tg.group_id IN (-10)
)
)
AND (topics.id NOT IN (68559,60069,42145))
AND "topics"."visible" = 't'
ORDER BY topics.bumped_at
DESC LIMIT 5;
```
Planning time: 1.196 ms
Execution time: 21.176 ms
```
EXPLAIN ANALYZE SELECT "topics".*
FROM "topics"
LEFT JOIN topic_users tu ON topics.id = tu.topic_id AND tu.user_id =
13455
LEFT JOIN topic_allowed_users ta ON topics.id = ta.topic_id AND
ta.user_id = 13455
LEFT JOIN topic_allowed_users ta2 ON topics.id = ta2.topic_id AND
ta2.user_id IN (2,1995,8307,17621,22980,-10)
LEFT JOIN topic_allowed_groups tg ON topics.id = tg.topic_id AND
tg.group_id IN (-10)
WHERE ("topics"."deleted_at" IS NULL)
AND (topics.archetype = 'private_message')
AND (ta.topic_id IS NOT NULL)
AND (ta2.topic_id IS NOT NULL OR tg.topic_id IS NOT NULL)
AND (topics.id NOT IN (68559,60069,42145))
AND "topics"."visible" = 't'
ORDER BY topics.bumped_at DESC
LIMIT 5;
```
Planning time: 1.792 ms
Execution time: 2.546 ms
Figuring out what unread topics a user has is a very expensive
operation over time.
Users can easily accumulate 10s of thousands of tracking state rows
(1 for every topic they ever visit)
When figuring out what a user has that is unread we need to join
the tracking state records to the topic table. This can very quickly
lead to cases where you need to scan through the entire topic table.
This commit optimises it so we always keep track of the "first" date
a user has unread topics. Then we can easily filter out all earlier
topics from the join.
We use pg functions, instead of nested queries here to assist the
planner.
- Regular users are not notified of whispers
- Regular users no longer have "stuck" topics in unread
- Additional tracking for staff highest post number
- Remove a bunch of unused columns in topics table
