[Feature] Revisit concurrency (#69)

* Leave Combine out of concurrency

* Safeguard against CB adding Sendable conformance to CBUUID

* Remove @MainActors

* Update README

Author: manolofdez

README.md

@@ -45,7 +45,7 @@ try await centralManager.connect(peripheral, options: nil)
 The central manager publishes several events. You can subscribe to them by using the `eventPublisher`.
 
 ```swift
-await centralManager.eventPublisher
+centralManager.eventPublisher
     .sink {
         switch $0 {
         case .didConnectPeripheral(let peripheral):
@@ -92,7 +92,7 @@ To get notified when a characteristic's value is updated, we provide a publisher
 
 ```swift
 let characteristicUUID = CBUUID()
-await peripheral.characteristicValueUpdatedPublisher
+peripheral.characteristicValueUpdatedPublisher
     .filter { $0.characteristic.uuid == characteristicUUID }
     .map { try? $0.parsedValue() as String? } // replace `String?` with your type
     .sink { value in
@@ -129,7 +129,7 @@ fetchTask.cancel()
 There might also be cases were you want to stop awaiting for all responses. For example, when bluetooth has been powered off. This can be done like so:
 
 ```swift
-await centralManager.eventPublisher
+centralManager.eventPublisher
     .sink {
         switch $0 {
         case .didUpdateState(let state):

Sources/CentralManager/CentralManager.swift

@@ -32,10 +32,9 @@ public final class CentralManager: Sendable {
         }
     }
 
-    @MainActor
     public var eventPublisher: AnyPublisher<CentralManagerEvent, Never> {
-        get async {
-            await self.context.eventSubject.eraseToAnyPublisher()
+        get {
+            self.context.eventSubject.eraseToAnyPublisher()
         }
     }
 
@@ -241,8 +240,8 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
     }()
 
     func centralManagerDidUpdateState(_ central: CBCentralManager) {
-        Task { @MainActor in
-            await self.context.eventSubject.send(.didUpdateState(state: central.state))
+        Task {
+            self.context.eventSubject.send(.didUpdateState(state: central.state))
 
             guard let isBluetoothReadyResult = Utils.isBluetoothReady(central.state) else { return }
 
@@ -251,9 +250,7 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
     }
 
     func centralManager(_ central: CBCentralManager, willRestoreState dict: [String : Any]) {
-        Task { @MainActor in
-            await self.context.eventSubject.send(.willRestoreState(state: dict))
-        }
+        self.context.eventSubject.send(.willRestoreState(state: dict))
     }
 
     func centralManager(
@@ -281,7 +278,7 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
     }
 
     func centralManager(_ cbCentralManager: CBCentralManager, didConnect peripheral: CBPeripheral) {
-        Task { @MainActor in
+        Task {
             Self.logger.info("Connected to peripheral \(peripheral.identifier)")
 
             do {
@@ -292,7 +289,7 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
                 Self.logger.info("Received onDidConnect without a continuation")
             }
 
-            await self.context.eventSubject.send(
+            self.context.eventSubject.send(
                 .didConnectPeripheral(peripheral: Peripheral(peripheral))
             )
         }
@@ -315,14 +312,9 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
             break
         }
 
-        Task { @MainActor in
-            await self.context.eventSubject.send(
-                .connectionEventDidOccur(
-                    connectionEvent: event,
-                    peripheral: peripheral
-                )
-            )
-        }
+        self.context.eventSubject.send(
+            .connectionEventDidOccur(connectionEvent: event, peripheral: peripheral)
+        )
     }
     #endif
 
@@ -353,7 +345,7 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
         isReconnecting: Bool,
         error: Error?
     ) {
-        Task { @MainActor in
+        Task {
             do {
                 let result = CallbackUtils.result(for: (), error: error)
                 try await self.context.cancelPeripheralConnectionExecutor.setWorkCompletedForKey(
@@ -364,7 +356,7 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
                 Self.logger.info("Disconnected from \(peripheral.identifier) without a continuation")
             }
 
-            await self.context.eventSubject.send(
+            self.context.eventSubject.send(
                 .didDisconnectPeripheral(peripheral: Peripheral(peripheral), isReconnecting: isReconnecting, error: error)
             )
         }
@@ -375,7 +367,7 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
         didDisconnectPeripheral peripheral: CBPeripheral,
         error: Error?
     ) {
-        Task { @MainActor in
+        Task {
             do {
                 let result = CallbackUtils.result(for: (), error: error)
                 try await self.context.cancelPeripheralConnectionExecutor.setWorkCompletedForKey(
@@ -386,7 +378,7 @@ extension CentralManager.DelegateWrapper: CBCentralManagerDelegate {
                 Self.logger.info("Disconnected from \(peripheral.identifier) without a continuation")
             }
 
-            await self.context.eventSubject.send(
+            self.context.eventSubject.send(
                 .didDisconnectPeripheral(peripheral: Peripheral(peripheral), isReconnecting: false, error: error)
             )
         }

Sources/CentralManager/CentralManagerContext.swift

@@ -26,11 +26,11 @@ actor CentralManagerContext {
 
     private(set) lazy var scanForPeripheralsContext = ScanForPeripheralsContext { [weak self] isScanning in
         Task { [weak self] in
-            await self?.updateIsScanning(isScanning)
+            self?.updateIsScanning(isScanning)
         }
     }
 
-    private(set) lazy var eventSubject = PassthroughSubject<CentralManagerEvent, Never>()
+    nonisolated private(set) lazy var eventSubject = PassthroughSubject<CentralManagerEvent, Never>()
 
     private(set) lazy var waitUntilReadyExecutor = {
         let executor = AsyncSerialExecutor<Void>()

Sources/Peripheral/Peripheral.swift

@@ -14,18 +14,16 @@ public final class Peripheral: Sendable {
     }
 
     /// Publishes characteristics that are notifying of value changes.
-    @MainActor
     public var characteristicValueUpdatedPublisher: AnyPublisher<CharacteristicValueUpdateEventData, Never> {
-        get async {
-            await self.context.characteristicValueUpdatedSubject.eraseToAnyPublisher()
+        get {
+            self.context.characteristicValueUpdatedSubject.eraseToAnyPublisher()
         }
     }
 
     /// Publishes when the services of the peripheral has changed.
-    @MainActor
     public var invalidatedServices: AnyPublisher<[Service], Never> {
-        get async {
-            await self.context.invalidatedServicesSubject.eraseToAnyPublisher()
+        get {
+            self.context.invalidatedServicesSubject.eraseToAnyPublisher()
         }
     }
 

Sources/Peripheral/PeripheralContext.swift

@@ -6,8 +6,8 @@ import Combine
 
 /// Contains the objects necessary to track a Peripheral's commands.
 actor PeripheralContext {
-    private(set) lazy var characteristicValueUpdatedSubject = PassthroughSubject<CharacteristicValueUpdateEventData, Never>()
-    private(set) lazy var invalidatedServicesSubject = PassthroughSubject<[Service], Never>()
+    nonisolated private(set) lazy var characteristicValueUpdatedSubject = PassthroughSubject<CharacteristicValueUpdateEventData, Never>()
+    nonisolated private(set) lazy var invalidatedServicesSubject = PassthroughSubject<[Service], Never>()
 
     private(set) lazy var readRSSIExecutor = {
         let executor = AsyncSerialExecutor<NSNumber>()

Sources/Peripheral/PeripheralDelegate.swift

@@ -67,9 +67,9 @@ extension PeripheralDelegate: CBPeripheralDelegate {
     func peripheral(_ cbPeripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
         let eventData = CharacteristicValueUpdateEventData(characteristic: Characteristic(characteristic))
 
-        Task { @MainActor in
+        Task {
             if characteristic.isNotifying {
-               await self.context.characteristicValueUpdatedSubject.send(eventData)
+               self.context.characteristicValueUpdatedSubject.send(eventData)
             }
 
             do {
@@ -169,8 +169,6 @@ extension PeripheralDelegate: CBPeripheralDelegate {
     }
 
     func peripheral(_ peripheral: CBPeripheral, didModifyServices invalidatedServices: [CBService]) {
-        Task { @MainActor in
-            await self.context.invalidatedServicesSubject.send(invalidatedServices.map { Service($0) })
-        }
+        self.context.invalidatedServicesSubject.send(invalidatedServices.map { Service($0) })
     }
 }

Sources/Utils/Extensions/CBUUID+Sendable.swift

@@ -3,4 +3,4 @@
 import Foundation
 import CoreBluetooth
 
-extension CBUUID: @unchecked Sendable {}
+extension CBUUID: @unchecked @retroactive Sendable {}