Add synchronized access to EventEngine's state property (#199)

fix(subscribe): fix the crash issue caused by multiple accesses to the `state` property in multithreaded scenarios

.github/workflows/run-tests.yml

@@ -24,7 +24,7 @@ jobs:
     strategy:
       matrix:
         environment: [iOS, tvOS, macOS]
-    timeout-minutes: 5
+    timeout-minutes: 7
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4

.pubnub.yml

@@ -1,9 +1,14 @@
 ---
 name: swift
 scm: github.com/pubnub/swift
-version: "8.2.4"
+version: "8.2.5"
 schema: 1
 changelog:
+  - date: 2025-01-16
+    version: 8.2.5
+    changes:
+      - type: bug
+        text: "Fix the crash issue caused by multiple accesses to the `state` property in multithreaded scenarios."
   - date: 2025-01-10
     version: 8.2.4
     changes:
@@ -643,7 +648,7 @@ sdks:
           - distribution-type: source
             distribution-repository: GitHub release
             package-name: PubNub
-            location: https://github.com/pubnub/swift/archive/refs/tags/8.2.4.zip
+            location: https://github.com/pubnub/swift/archive/refs/tags/8.2.5.zip
             supported-platforms:
               supported-operating-systems:
                 macOS:

PubNub.xcodeproj/project.pbxproj

@@ -3999,7 +3999,7 @@
 					"@loader_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu11 gnu++17";
 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
 				MTL_FAST_MATH = YES;
@@ -4050,7 +4050,7 @@
 					"@loader_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu11 gnu++17";
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
@@ -4158,7 +4158,7 @@
 					"@loader_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu11 gnu++17";
 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
 				MTL_FAST_MATH = YES;
@@ -4211,7 +4211,7 @@
 					"@loader_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu11 gnu++17";
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
@@ -4332,7 +4332,7 @@
 					"@loader_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu11 gnu++17";
 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
 				MTL_FAST_MATH = YES;
@@ -4384,7 +4384,7 @@
 					"@loader_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu11 gnu++17";
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
@@ -4864,7 +4864,7 @@
 					"$(TOOLCHAIN_DIR)/usr/lib/swift/macosx",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu17 gnu++14";
 				OTHER_CFLAGS = "$(inherited)";
 				OTHER_LDFLAGS = "$(inherited)";
@@ -4907,7 +4907,7 @@
 					"$(TOOLCHAIN_DIR)/usr/lib/swift/macosx",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 10.15;
-				MARKETING_VERSION = 8.2.4;
+				MARKETING_VERSION = 8.2.5;
 				MODULE_VERIFIER_SUPPORTED_LANGUAGE_STANDARDS = "gnu17 gnu++14";
 				OTHER_CFLAGS = "$(inherited)";
 				OTHER_LDFLAGS = "$(inherited)";

PubNubSwift.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name     = 'PubNubSwift'
-  s.version  = '8.2.4'
+  s.version  = '8.2.5'
   s.homepage = 'https://github.com/pubnub/swift'
   s.documentation_url = 'https://www.pubnub.com/docs/swift-native/pubnub-swift-sdk'
   s.authors = { 'PubNub, Inc.' => '[email protected]' }

Sources/PubNub/EventEngine/Core/EventEngine.swift

@@ -17,7 +17,20 @@ struct EventEngineDependencies<Dependencies> {
 class EventEngine<State, Event, Invocation: AnyEffectInvocation, Input> {
   private let transition: any TransitionProtocol<State, Event, Invocation>
   private let dispatcher: any Dispatcher<Invocation, Event, Input>
-  private(set) var state: State
+  private let recursiveLock = NSRecursiveLock()
+  private var internalStateContainer: State
+
+  private(set) var state: State {
+    get {
+      recursiveLock.lock()
+      defer { recursiveLock.unlock() }
+      return internalStateContainer
+    } set {
+      recursiveLock.lock()
+      defer { recursiveLock.unlock() }
+      internalStateContainer = newValue
+    }
+  }
 
   var dependencies: EventEngineDependencies<Input>
   var onStateUpdated: ((State) -> Void)?
@@ -29,27 +42,30 @@ class EventEngine<State, Event, Invocation: AnyEffectInvocation, Input> {
     dispatcher: some Dispatcher<Invocation, Event, Input>,
     dependencies: EventEngineDependencies<Input>
   ) {
-    self.state = state
+    self.internalStateContainer = state
     self.onStateUpdated = onStateUpdated
     self.transition = transition
     self.dispatcher = dispatcher
     self.dependencies = dependencies
   }
 
   func send(event: Event) {
-    objc_sync_enter(self)
+    recursiveLock.lock()
 
     defer {
-      objc_sync_exit(self)
+      recursiveLock.unlock()
     }
+
+    let currentState = state
+
     guard transition.canTransition(
-      from: state,
+      from: currentState,
       dueTo: event
     ) else {
       return
     }
 
-    let transitionResult = transition.transition(from: state, event: event)
+    let transitionResult = transition.transition(from: currentState, event: event)
     let invocations = transitionResult.invocations
 
     state = transitionResult.state

Sources/PubNub/Helpers/Constants.swift

@@ -57,7 +57,7 @@ public enum Constant {
 
   static let pubnubSwiftSDKName: String = "PubNubSwift"
 
-  static let pubnubSwiftSDKVersion: String = "8.2.4"
+  static let pubnubSwiftSDKVersion: String = "8.2.5"
 
   static let appBundleId: String = {
     if let info = Bundle.main.infoDictionary,

fastlane/.env.ios

@@ -1,7 +1,7 @@
-DEVICES="iPhone 13 (15.5),iPhone 15 (17.5)"
-COVERAGE="iPhone 15 (17.5)"
+DEVICES="generic/platform=iOS Simulator"
+COVERAGE="generic/platform=iOS Simulator"
 
-DESTINATION_EXAMPLE="OS=17.4,name=iPhone 15"
+DESTINATION_EXAMPLE="generic/platform=iOS Simulator"
 TEST_OUTPUT_DIR="fastlane/test_output/iOS"
 SCHEME_EXAMPLE=Example-iOS
 PLATFORM=ios

fastlane/.env.tvos

@@ -1,5 +1,5 @@
-DEVICES="Apple TV (15.4),Apple TV (17.5)"
-COVERAGE="Apple TV (17.5)"
+DEVICES="generic/platform=tvOS Simulator"
+COVERAGE="generic/platform=tvOS Simulator"
 
 TEST_OUTPUT_DIR="fastlane/test_output/tvOS"
 PLATFORM=tvos