Previously we were publishing one messagebus message per user which was 'tracking' a topic. On large sites, this can easily be 1000+ messages. The important information in the message is common between all users, so we can manage with a single message on a shared channel, which will be much more efficient.
For user-specific values (notification_level and last_read_post_number), the JS app can infer values which are 'good enough'. Correct values will be loaded as soon as a topic-list containing the topic is visited.
There are certain design decisions that were made in this commit.
Private messages implements its own version of topic tracking state because there are significant differences between regular and private_message topics. Regular topics have to track categories and tags while private messages do not. It is much easier to design the new topic tracking state if we maintain two different classes, instead of trying to mash this two worlds together.
One MessageBus channel per user and one MessageBus channel per group. This allows each user and each group to have their own channel backlog instead of having one global channel which requires the client to filter away unrelated messages.
This allows us to do DISTINCT on the topic_id to remove
duplicates (e.g. in extensions to the report SQL), and
also introduces an additional_join_sql string to allow
extensions to JOIN additional tables.
I merged this PR in yesterday, finally thinking this was done https://github.com/discourse/discourse/pull/12958 but then a wild performance regression occurred. These are the problem methods:
1aa20bd681/app/serializers/topic_tracking_state_serializer.rb (L13-L21)
Turns out date comparison is super expensive on the backend _as well as_ the frontend.
The fix was to just move the `treat_as_new_topic_start_date` into the SQL query rather than using the slower `UserOption#treat_as_new_topic_start_date` method in ruby. After this change, 1% of the total time is spent with the `created_in_new_period` comparison instead of ~20%.
----
History:
Original PR which had to be reverted **https://github.com/discourse/discourse/pull/12555**. See the description there for what this PR is achieving, plus below.
The issue with the original PR is addressed in 92ef54f402
If you went to the `x unread` link for a tag Chrome would freeze up and possibly crash, or eventually unfreeze after nearly 10 mins. Other routes for unread/new were similarly slow. From profiling the issue was the `sync` function of `topic-tracking-state.js`, which calls down to `isNew` which in turn calls `moment`, a change I had made in the PR above. The time it takes locally with ~1400 topics in the tracking state is 2.3 seconds.
To solve this issue, I have moved these calculations for "created in new period" and "unread not too old" into the tracking state serializer.
When I was looking at the profiler I also noticed this issue which was just compounding the problem. Every time we modify topic tracking state we recalculate the sidebar tracking/everything/tag counts. However this calls `forEachTracked` and `countTags` which can be quite expensive as they go through the whole tracking state (and were also calling the removed moment functions).
I added some logs and this was being called 30 times when navigating to a new /unread route because `sync` is being called from `build-topic-route` (one for each topic loaded due to pagination). So I just added a debounce here and it makes things even faster.
Finally, I changed topic tracking state to use a Map so our counts of the state keys is faster (Maps have .size whereas objects you have to do Object.keys(obj) which is O(n).)
<!-- NOTE: All pull requests should have tests (rspec in Ruby, qunit in JavaScript). If your code does not include test coverage, please include an explanation of why it was omitted. -->
Original PR which had to be reverted **https://github.com/discourse/discourse/pull/12555**. See the description there for what this PR is achieving, plus below.
The issue with the original PR is addressed in 92ef54f402
If you went to the `x unread` link for a tag Chrome would freeze up and possibly crash, or eventually unfreeze after nearly 10 mins. Other routes for unread/new were similarly slow. From profiling the issue was the `sync` function of `topic-tracking-state.js`, which calls down to `isNew` which in turn calls `moment`, a change I had made in the PR above. The time it takes locally with ~1400 topics in the tracking state is 2.3 seconds.
To solve this issue, I have moved these calculations for "created in new period" and "unread not too old" into the tracking state serializer.
When I was looking at the profiler I also noticed this issue which was just compounding the problem. Every time we modify topic tracking state we recalculate the sidebar tracking/everything/tag counts. However this calls `forEachTracked` and `countTags` which can be quite expensive as they go through the whole tracking state (and were also calling the removed moment functions).
I added some logs and this was being called 30 times when navigating to a new /unread route because `sync` is being called from `build-topic-route` (one for each topic loaded due to pagination). So I just added a debounce here and it makes things even faster.
Finally, I changed topic tracking state to use a Map so our counts of the state keys is faster (Maps have .size whereas objects you have to do Object.keys(obj) which is O(n).)
Over the years we accrued many spelling mistakes in the code base.
This PR attempts to fix spelling mistakes and typos in all areas of the code that are extremely safe to change
- comments
- test descriptions
- other low risk areas
The aim of this PR is to improve the topic tracking state JavaScript code and test coverage so further modifications can be made in plugins and in core. This is focused on making topic tracking state changes easier to respond to with callbacks, and changing it so all state modifications go through a single method instead of modifying `this.state` all over the place. I have also tried to improve documentation, make the code clearer and easier to follow, and make it clear what are public and private methods.
The changes I have made here should not break backwards compatibility, though there is no way to tell for sure if other plugin/theme authors are using tracking state methods that are essentially private methods. Any name changes made in the tracking-state.js code have been reflected in core.
----
We now have a `_trackedTopicLimit` in the tracking state. Previously, if a topic was neither new nor unread it was removed from the tracking state; now it is only removed if we are tracking more than `_trackedTopicLimit` topics (which is set to 4000). This is so plugins/themes adding topics with `TopicTrackingState.register_refine_method` can add topics to track that aren't necessarily new or unread, e.g. for totals counts.
Anywhere where we were doing `tracker.states["t" + data.topic_id] = newObject` has now been changed to flow through central `modifyState` and `modifyStateProp` methods. This is so state objects are not modified until they need to be (e.g. sometimes properties are set based on certain conditions) and also so we can run callback functions when the state is modified.
I added `onStateChange` and `onMessageIncrement` methods to register callbacks that are called when the state is changed and when the message count is incremented, respectively. This was done so we no longer need to do things like `@observes("trackingState.states")` in other Ember classes.
I split up giant functions like `sync` and `establishChannels` into smaller functions for readability and testability, and renamed many small functions to _functionName to designate them as private functions which not be called by consumers of `topicTrackingState`. Public functions are now all documented (well...at least ones that are not immediately obvious).
----
On the backend side, I have changed the MessageBus publish events for TopicTrackingState to send back tags and tag IDs for more channels, and done some extra code cleanup and refactoring. Plugins may override `TopicTrackingState.report` so I have made its footprint as small as possible and externalised the main parts of it into other methods.
Original PR was reverted because of broken migration https://github.com/discourse/discourse/pull/12058
I fixed it by adding this line
```
AND topics.id IN(SELECT id FROM topics ORDER BY created_at DESC LIMIT :max_new_topics)
```
This time it is left joining a limited amount of topics. I tested it on few databases and it worked quite smooth
Follow up https://github.com/discourse/discourse/pull/11968
Dismiss all new topics using the same DismissTopicService. In addition, MessageBus receives exact topic ids which should be marked as `seen`.
* FEATURE: Ability to dismiss new topics in a specific tag
Follow up of https://github.com/discourse/discourse/pull/11927
Using the same mechanism to disable new topics in a tag.
* FIX: respect when category and tag is selected
This is a try to simplify logic around dismiss new topics to have one solution to work in all places - dismiss all-new, dismiss new in a specific category or even in a specific tag.
* DEV: Remove with_deleted workarounds for old Rails version
These workarounds using private APIs are no longer required in the latest version of Rails. The referenced issue (https://github.com/rails/rails/issues/4306) was closed in 2013. The acts_as_paranoid workaround which this was based on was removed for rails > 5.
Switching to using a scope also allows us to use it within a `belongs_to` relation (e.g. in the Poll model). This avoids issues which can be caused by unscoping all `where` clauses.
Predicates are not necessarily strings, so calling `.join(" AND ")` can sometimes cause weird errors. If we use `WhereClause#ast`, and then `.to_sql` we achieve the same thing with fully public APIs, and it will work successfully for all predicates.
PostDestroyer should accept the option to permanently destroy post from the database. In addition, when the first post is destroyed it destroys the whole topic.
Currently, that feature is limited to private messages and creator of the post. It will be used by discourse-encrypt to explode encrypted private messages.
We previously did not account for completely untagged topics when
looking at muted tags, this caused new/unread counts to be off if
1. You had muted tags
2. You had an unread/new topic
3. This topic had no tags
This feature allows certain plugins to output tag information
to topic tracking state, this allows per tag stats which can be
used by sidebars and other plugins that need per tag stats
Not enabled by default cause this would add cost to a critical
query
Recently, we added feature that we are sending `/muted` to users who muted specific topic just before `/latest` so the client knows to ignore those messages - https://github.com/discourse/discourse/pull/9482
Same `/muted` message should be included when the post is edited
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
* FEATURE: don't display new/unread notification for muted topics
Currently, even if user mute topic, when a new reply to that topic arrives, the user will get "See 1 new or updated topic" message. After clicking on that link, nothing is visible (because the topic is muted)
To solve that problem, we will send background message to all users who recently muted that topic that update is coming and they can ignore the next message about that topic.
6e1fe22 introduced the possiblity for category_users to have a NULL notification_level, so that we can store `last_seen_at` dates without locking the notification level. At the time, this did not affect the topic-tracking-state query. However, the query changes in f434de2 introduced a slight change in behavior.
Previously, a subquery would look for a category_user with notification_level=mute. f434de2 refactored this to remove the subquery, and inverted some of the logic to suit.
The new query checked for `notification_level <> :muted`. If `notification_level` is NULL, this comparison will return NULL. In this scenario, notification_level=NULL means that we should fall back to the default tracking level (regular), and so we want the expression to resolve as true, not false. There was already a check for the existence of the category_users row, but it did not check for the existence of a NOT NULL notification_level.
This commit amends the expression so that the notification_level will only be compared if it is non-null.
When the tag is muted and topic contains that tag, we should not mark that message as NEW.
There are 3 possible settings which site admin can set.
remove_muted_tags_from_latest - always
It means that if the topic got at least one muted tag, we should not mark that topic as NEW
remove_muted_tags_from_latest - only muted
Similar to above, however, if at least one tag is not muted, the topic is marked as NEW
remove_muted_tags_from_latest - never
Basically, mute tag setting is ignored and all topics are set as NEW
When category is dismissed, `dismiss_new` message is sent to fronted to clean state.
In addition, I noticed that when old dismiss new button is clicked, no message is sent so I decided to kill two birds with one stone.
* The read indicator now shows up when no member has read the last post of the topic (written by a non-member)
* The read indicator works on mobile and receives live updates from message bus
* The icon we display in the topic list was changed
* Added a title to the indicator to indicate its purpose when hovering over it
Krzysztof Kotlarek
David Taylor
Alan Guo Xiang Tan
Martin Brennan
Osama Sayegh
Josh Soref
Kris
Sam Saffron
Mark VanLandingham
Joffrey JAFFEUX
Roman Rizzi