Add StateLayerEventPublisher for centralised change handling #15

laevandus · 2025-09-16T08:44:43Z

🔗 Issue Links

🎯 Goal

Add centralised event handler for state-layer so that we can use it when receiving WS events and when calling changes manually after API calls.

📝 Summary

Add StateLayerEventPublisher which converts WS events to custom and simplified events only for state-layer updates
StateLayerEventPublisher allows moving event filtering logic to a single handler running on the background thread
StateLayerEventPublisher allows converting event data once and forwarding the final data to all the observers
Used StateLayerEventPublisher in Activity and added extensive tests to Activity
Tidied many of the dummy functions
Added support for parallel API request mocking in tests\
Add addReaction and deleteReaction to Activity

🛠 Implementation

Centralised handler allows having filtering in a single handler running on a background thread. Before the filtering was in the WS event observer only which causes issues when change handlers were called directly after API calls. Especially problematic with queries with filters where the change might not match the query anymore.

🎨 Showcase

Add relevant screenshots and/or videos/gifs to easily see what this PR changes, if applicable.

Before	After
img	img

🧪 Manual Testing Notes

☑️ Contributor Checklist

I have signed the Stream CLA (required)
This change should be manually QAed
Changelog is updated with client-facing changes
Changelog is updated with new localization keys
New code is covered by unit tests
Documentation has been updated in the docs-content repo

Use it in Activity and ActivityState Cover Activity type with tests

laevandus · 2025-09-16T08:45:51Z

Sources/StreamFeeds/Repositories/ActivitiesRepository.swift

+        if flag {
+            let response = try await apiClient.pinActivity(feedGroupId: feed.group, feedId: feed.id, activityId: activityId)
+            return response.activity.toModel()
+        } else {
+            let response = try await apiClient.unpinActivity(feedGroupId: feed.group, feedId: feed.id, activityId: activityId)
+            return response.activity.toModel()
+        }


Found a bug while writing tests, unpin was never called

github-actions · 2025-09-16T08:45:55Z

	1 Warning
⚠️	Big PR

	1 Message
📖	There seems to be app changes but CHANGELOG wasn't modified. Please include an entry if the PR includes user-facing changes. You can find it at CHANGELOG.md.

Generated by 🚫 Danger

github-actions · 2025-09-16T08:46:13Z

Public Interface

 public final class Activity: Sendable  
-   @discardableResult public func addCommentReaction(commentId: String,request: AddCommentReactionRequest)async throws -> FeedsReactionData
+   @discardableResult public func addReaction(request: AddReactionRequest)async throws -> FeedsReactionData
-   @discardableResult public func deleteCommentReaction(commentId: String,type: String)async throws -> FeedsReactionData
+   @discardableResult public func deleteReaction(type: String)async throws -> FeedsReactionData
-   public func pin()async throws 
+   @discardableResult public func addCommentReaction(commentId: String,request: AddCommentReactionRequest)async throws -> FeedsReactionData
-   public func unpin()async throws 
+   @discardableResult public func deleteCommentReaction(commentId: String,type: String)async throws -> FeedsReactionData
-   @discardableResult public func closePoll()async throws -> PollData
+   public func pin()async throws 
-   public func deletePoll(userId: String? = nil)async throws 
+   public func unpin()async throws 
-   @discardableResult public func getPoll(userId: String? = nil)async throws -> PollData
+   @discardableResult public func closePoll()async throws -> PollData
-   @discardableResult public func updatePollPartial(request: UpdatePollPartialRequest)async throws -> PollData
+   public func deletePoll(userId: String? = nil)async throws 
-   @discardableResult public func updatePoll(request: UpdatePollRequest)async throws -> PollData
+   @discardableResult public func getPoll(userId: String? = nil)async throws -> PollData
-   @discardableResult public func createPollOption(request: CreatePollOptionRequest)async throws -> PollOptionData
+   @discardableResult public func updatePollPartial(request: UpdatePollPartialRequest)async throws -> PollData
-   public func deletePollOption(optionId: String,userId: String? = nil)async throws 
+   @discardableResult public func updatePoll(request: UpdatePollRequest)async throws -> PollData
-   @discardableResult public func getPollOption(optionId: String,userId: String?)async throws -> PollOptionData
+   @discardableResult public func createPollOption(request: CreatePollOptionRequest)async throws -> PollOptionData
-   @discardableResult public func updatePollOption(request: UpdatePollOptionRequest)async throws -> PollOptionData
+   public func deletePollOption(optionId: String,userId: String? = nil)async throws 
-   @discardableResult public func castPollVote(request: CastPollVoteRequest)async throws -> PollVoteData?
+   @discardableResult public func getPollOption(optionId: String,userId: String?)async throws -> PollOptionData
-   @discardableResult public func deletePollVote(voteId: String,userId: String? = nil)async throws -> PollVoteData?
+   @discardableResult public func updatePollOption(request: UpdatePollOptionRequest)async throws -> PollOptionData
+   @discardableResult public func castPollVote(request: CastPollVoteRequest)async throws -> PollVoteData?
+   @discardableResult public func deletePollVote(voteId: String,userId: String? = nil)async throws -> PollVoteData?

laevandus · 2025-09-16T08:47:11Z

Sources/StreamFeeds/StateLayer/Common/StateLayerEventPublisher.swift

+        await withTaskGroup(of: Void.self) { group in
+            for handler in handlers {
+                group.addTask {
+                    await handler(event)
+                }
+            }
+        }


Makes sure handler runs on a background thread which is good when handler wants to do complex filtering, aka local filter matching

Stream-SDK-Bot · 2025-09-16T08:51:27Z

SDK Size

`title`	`develop`	`branch`	`diff`	`status`
StreamFeeds	6.16 MB	6.21 MB	+51 KB	🟢

martinmitrevski

Looks good, left few comments. Also, I think there are still some bugs in the state layer.

martinmitrevski · 2025-09-16T11:19:59Z

Sources/StreamFeeds/StateLayer/ActivityState.swift

+    private func subscribe(to publisher: StateLayerEventPublisher) {
+        eventObserver = publisher.subscribe { [weak self, activityId, feed] event in
+            switch event {
+            case .activityUpdated(let activityData, let eventFeedId):


seems like we still have a bug with activity reactions - e.g. if the initial state is 1, you react, it becomes 3. Remove reaction, it becomes 1.

Bookmarks also still don't work well (own issue, maybe backend?)

I did a quick fix in this PR since the issue comes from the Feed type. Next PR is going to be about Feed, its event handling and adding tests.

I was able to reproduce this myself as well and now it does not happen.

Sources/StreamFeeds/StateLayer/Common/StateLayerEventPublisher.swift

martinmitrevski · 2025-09-16T11:23:05Z

Sources/StreamFeeds/StateLayer/Common/StateLayerEventPublisher.swift

+}
+
+extension StateLayerEventPublisher {
+    final class ObservationToken: Sendable {


Maybe we call this Subscription? That's what we also use for video.

Sounds good! Done

martinmitrevski · 2025-09-16T11:24:02Z

Sources/StreamFeeds/StateLayer/Common/StateLayerEventPublisher.swift

+    final class ObservationToken: Sendable {
+        private let action: @Sendable () -> Void
+
+        init(action: @escaping @Sendable () -> Void) {


Also action is a bit misleading here, maybe we should be more explicit here with the name?

Renamed it to cancel

Add StateLayerEventPublisher for centralised change handling

ed69ddf

Use it in Activity and ActivityState Cover Activity type with tests

laevandus requested a review from a team as a code owner September 16, 2025 08:44

laevandus added the ✅ Feature An issue or PR related to a feature label Sep 16, 2025

laevandus commented Sep 16, 2025

View reviewed changes

martinmitrevski reviewed Sep 16, 2025

View reviewed changes

laevandus added 2 commits September 16, 2025 14:33

Use Subscription term and fix typos

b375486

Fix comment and reaction count mutations

04b7c69

martinmitrevski approved these changes Sep 16, 2025

View reviewed changes

Add addReaction and deleteReaction to Activity

a1a449d

laevandus enabled auto-merge (squash) September 16, 2025 12:26

laevandus merged commit cfbb649 into develop Sep 16, 2025
5 checks passed

laevandus deleted the refactor-state-layer-event-handling-in-activity branch September 16, 2025 12:32

gpunto mentioned this pull request Sep 24, 2025

Add StateUpdateEvent and relative code, and migrate ActivityCommentList to consuming it GetStream/stream-feeds-android#83

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laevandus commented Sep 16, 2025 •

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🔗 Issue Links

🎯 Goal

📝 Summary

🛠 Implementation

🎨 Showcase

🧪 Manual Testing Notes

☑️ Contributor Checklist

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laevandus commented Sep 16, 2025 •

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