Make CoreSDK callback-based

[lawrence-forooghian]

Replace CoreSDK's publish and fetchServerTime methods to use callbacks and expect to be called on the internal queue. The usage of async methods was not a good mix with the rest of this plugin's heavy usage of the internal queue as its synchronisation mechanism, and led to a lot of switching between normal code and async code which was hard to read.

Each caller now enters the internal queue once via withCheckedContinuation + dispatchQueue.async and stays there through the whole operation chain, eliminating repeated queue hops.

Summary by CodeRabbit

• Refactor
  • Updated internal asynchronous operation handling to use callback-based completion patterns for publish and server time fetching operations.
  • Modified related operations in counters, maps, and object creation to align with the callback-based architecture.

[coderabbitai]

Walkthrough

This pull request converts callback-based asynchronous operations in the Ably Live Objects SDK from async/throws patterns to non-blocking callback signatures. Protocol methods and implementations are refactored to use Result-type callbacks routed through internal queues, with consumer code bridged via CheckedContinuation for external async compatibility.

Changes

Cohort / File(s)	Summary
Core Protocol & Implementation Sources/AblyLiveObjects/Internal/CoreSDK.swift, Sources/AblyLiveObjects/Internal/DefaultInternalPlugin.swift, Tests/AblyLiveObjectsTests/Mocks/MockCoreSDK.swift	Protocol methods publish and fetchServerTime converted from async throws to callback-based with Result<Void/Date, ARTErrorInfo>. DefaultCoreSDK routes callbacks to internal queue; DefaultInternalPlugin's sendObject refactored to callback pattern. Mock implementations updated to dispatch callbacks on channel state queue.
Live Object Types Sources/AblyLiveObjects/Internal/InternalDefaultLiveCounter.swift, Sources/AblyLiveObjects/Internal/InternalDefaultLiveMap.swift	Methods increment, set, and remove rewritten with CheckedContinuation wrappers. Input validation added for counter amount finiteness. Publish operations now use nosync\_publish callbacks routed through continuations.
Live Objects Container Sources/AblyLiveObjects/Internal/InternalDefaultRealtimeObjects.swift	Methods createMap, createCounter, and testsOnly_publish refactored to use CheckedContinuation with nested callback handling. Server time fetching via nosync\_fetchServerTime and publish via nosync\_publish now route results through continuation resumption.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 Callbacks flow like a gentle stream,
No async await in this new scheme,
Continuations bridge the old and new,
Results wrapped tight, the pattern's true!
Hops forward now, non-blocking and lean. 🚀

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 28.57% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Make CoreSDK callback-based' directly and clearly summarizes the main change: converting CoreSDK methods from async/throws to callback-based APIs, which is the central objective of this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch make-CoreSDK-use-callbacks

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@Tests/AblyLiveObjectsTests/Mocks/MockCoreSDK.swift`:
- Around line 18-28: The read of _publishHandler in nosync_publish is not
synchronized with the write in setPublishHandler, causing a race; fix by reading
_publishHandler under the same channelStateMutex lock (use
channelStateMutex.withLock or equivalent) to capture the handler into a local
variable before creating the Task, then bail out if nil; refer to
nosync_publish, setPublishHandler, _publishHandler, and channelStateMutex when
making the change.

---

ℹ️ Review info

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Disabled knowledge base sources:

• Jira integration is disabled

You can enable these sources in your CodeRabbit configuration.

📥 Commits

Reviewing files that changed from the base of the PR and between db28b94 and 08cc139.

📒 Files selected for processing (6)

• Sources/AblyLiveObjects/Internal/CoreSDK.swift
• Sources/AblyLiveObjects/Internal/DefaultInternalPlugin.swift
• Sources/AblyLiveObjects/Internal/InternalDefaultLiveCounter.swift
• Sources/AblyLiveObjects/Internal/InternalDefaultLiveMap.swift
• Sources/AblyLiveObjects/Internal/InternalDefaultRealtimeObjects.swift
• Tests/AblyLiveObjectsTests/Mocks/MockCoreSDK.swift

[coderabbitai]

⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

cat -n Tests/AblyLiveObjectsTests/Mocks/MockCoreSDK.swift

Repository: ably/ably-liveobjects-swift-plugin

Length of output: 2471

---

Guard _publishHandler reads with mutex.withLock.

_publishHandler is written under lock in setPublishHandler (line 44-45) but read without lock in nosync_publish (line 19). This asymmetric synchronization can cause race conditions and test flakiness.

Suggested fix

func nosync_publish(objectMessages: [OutboundObjectMessage], callback: `@escaping` `@Sendable` (Result<Void, ARTErrorInfo>) -> Void) {
-    if let handler = _publishHandler {
+    let handler = mutex.withLock { _publishHandler }
+    if let handler {
         let queue = channelStateMutex.dispatchQueue
         Task {
             do throws(ARTErrorInfo) {
                 try await handler(objectMessages)
                 queue.async { callback(.success(())) }
             } catch {
                 queue.async { callback(.failure(error)) }
             }
         }
     } else {
         protocolRequirementNotImplemented()
     }
 }

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@Tests/AblyLiveObjectsTests/Mocks/MockCoreSDK.swift` around lines 18 - 28, The
read of _publishHandler in nosync_publish is not synchronized with the write in
setPublishHandler, causing a race; fix by reading _publishHandler under the same
channelStateMutex lock (use channelStateMutex.withLock or equivalent) to capture
the handler into a local variable before creating the Task, then bail out if
nil; refer to nosync_publish, setPublishHandler, _publishHandler, and
channelStateMutex when making the change.