Add full data-race safety and enable strict concurrency checking for Swift 6 compatibility

.editorconfig

@@ -0,0 +1,14 @@
+# EditorConfig is awesome: https://editorconfig.org
+root = true
+
+[*]
+
+indent_style = space
+tab_width = 8
+indent_size = 4
+
+end_of_line = lf
+insert_final_newline = true
+
+max_line_length = 160
+trim_trailing_whitespace = true

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.9
+// swift-tools-version: 5.9
 import PackageDescription
 
 let package = Package(
@@ -19,15 +19,18 @@ let package = Package(
         .target(
             name: "TelemetryDeck",
             dependencies: ["TelemetryClient"],
-            resources: [.copy("PrivacyInfo.xcprivacy")]
+            resources: [.copy("PrivacyInfo.xcprivacy")],
+            swiftSettings: [.enableExperimentalFeature("StrictConcurrency")]
         ),
         .target(
             name: "TelemetryClient",
-            resources: [.copy("PrivacyInfo.xcprivacy")]
+            resources: [.copy("PrivacyInfo.xcprivacy")],
+            swiftSettings: [.enableExperimentalFeature("StrictConcurrency")]
         ),
         .testTarget(
             name: "TelemetryClientTests",
-            dependencies: ["TelemetryClient"]
+            dependencies: ["TelemetryClient"],
+            swiftSettings: [.enableExperimentalFeature("StrictConcurrency")]
         )
     ]
 )

Sources/TelemetryClient/JSONFormatting.swift

@@ -1,19 +1,19 @@
 import Foundation
 
 extension Formatter {
-    static let iso8601: ISO8601DateFormatter = {
+    static var iso8601: ISO8601DateFormatter {
         let formatter = ISO8601DateFormatter()
         formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
         return formatter
-    }()
+    }
 
-    static let iso8601noFS = ISO8601DateFormatter()
+    static var iso8601noFS: ISO8601DateFormatter { ISO8601DateFormatter() }
 
-    static let iso8601dateOnly: ISO8601DateFormatter = {
+    static var iso8601dateOnly: ISO8601DateFormatter {
         let formatter = ISO8601DateFormatter()
         formatter.formatOptions = [.withFullDate]
         return formatter
-    }()
+    }
 }
 
 extension JSONDecoder.DateDecodingStrategy {
@@ -28,33 +28,33 @@ extension JSONDecoder.DateDecodingStrategy {
 }
 
 extension JSONDecoder {
-    static var telemetryDecoder: JSONDecoder = {
+    static var telemetryDecoder: JSONDecoder {
         let decoder = JSONDecoder()
         let dateFormatter = DateFormatter()
         dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
         dateFormatter.locale = Locale(identifier: "en_US")
         dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
         decoder.dateDecodingStrategy = .formatted(dateFormatter)
         return decoder
-    }()
+    }
 
-    static var druidDecoder: JSONDecoder = {
+    static var druidDecoder: JSONDecoder {
         let decoder = JSONDecoder()
         decoder.dateDecodingStrategy = .customISO8601
         return decoder
-    }()
+    }
 }
 
 extension JSONEncoder {
-    static var telemetryEncoder: JSONEncoder = {
+    static var telemetryEncoder: JSONEncoder {
         let encoder = JSONEncoder()
         let dateFormatter = DateFormatter()
         dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
         dateFormatter.locale = Locale(identifier: "en_US")
         dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
         encoder.dateEncodingStrategy = .formatted(dateFormatter)
         return encoder
-    }()
+    }
 }
 
 extension Data {

Sources/TelemetryClient/LogHandler.swift

@@ -1,7 +1,7 @@
 import Foundation
 
-public struct LogHandler {
-    public enum LogLevel: Int, CustomStringConvertible {
+public struct LogHandler: Sendable {
+    public enum LogLevel: Int, CustomStringConvertible, Sendable {
         case debug = 0
         case info = 1
         case error = 2
@@ -19,9 +19,9 @@ public struct LogHandler {
     }
 
     let logLevel: LogLevel
-    let handler: (LogLevel, String) -> Void
+    let handler: @Sendable (LogLevel, String) -> Void
 
-    public init(logLevel: LogHandler.LogLevel, handler: @escaping (LogHandler.LogLevel, String) -> Void) {
+    public init(logLevel: LogHandler.LogLevel, handler: @escaping @Sendable (LogHandler.LogLevel, String) -> Void) {
         self.logLevel = logLevel
         self.handler = handler
     }
@@ -32,7 +32,7 @@ public struct LogHandler {
         }
     }
 
-    public static var stdout = { logLevel in
+    public static func stdout(_ logLevel: LogLevel) -> LogHandler {
         LogHandler(logLevel: logLevel) { level, message in
             print("[TelemetryDeck: \(level.description)] \(message)")
         }

Sources/TelemetryClient/Presets/NavigationStatus.swift

@@ -2,6 +2,7 @@ import Foundation
 
 /// This internal singleton keeps track of the last used navigation path so
 /// that the ``TelemetryDeck.navigationPathChanged(to:customUserID:)`` function has a `from` source to work off of.
+@MainActor
 class NavigationStatus {
     static let shared = NavigationStatus()
 

Sources/TelemetryClient/Presets/TelemetryDeck+Navigation.swift

@@ -19,6 +19,7 @@ extension TelemetryDeck {
     ///     - from: The navigation path at the beginning of the navigation event, identifying the view the user is leaving
     ///     - to: The navigation path at the end of the navigation event, identifying the view the user is arriving at
     ///     - customUserID: An optional string specifying a custom user identifier. If provided, it will override the default user identifier from the configuration. Default is `nil`.
+    @MainActor
     public static func navigationPathChanged(from source: String, to destination: String, customUserID: String? = nil) {
         NavigationStatus.shared.previousNavigationPath = destination
 
@@ -57,17 +58,20 @@ extension TelemetryDeck {
     /// - Parameters:
     ///     - to: The navigation path representing the view the user is arriving at.
     ///     - customUserID: An optional string specifying a custom user identifier. If provided, it will override the default user identifier from the configuration. Default is `nil`.
+    @MainActor
     public static func navigationPathChanged(to destination: String, customUserID: String? = nil) {
         let source = NavigationStatus.shared.previousNavigationPath ?? ""
 
         Self.navigationPathChanged(from: source, to: destination, customUserID: customUserID)
     }
 
+    @MainActor
     @available(*, unavailable, renamed: "navigationPathChanged(from:to:customUserID:)")
     public static func navigate(from source: String, to destination: String, customUserID: String? = nil) {
         self.navigationPathChanged(from: source, to: destination, customUserID: customUserID)
     }
 
+    @MainActor
     @available(*, unavailable, renamed: "navigationPathChanged(to:customUserID:)")
     public static func navigate(to destination: String, customUserID: String? = nil) {
         self.navigationPathChanged(to: destination, customUserID: customUserID)

Sources/TelemetryClient/Signal.swift

@@ -41,6 +41,7 @@ internal struct SignalPostBody: Codable, Equatable {
 
 /// The default payload that is included in payloads processed by TelemetryDeck.
 public struct DefaultSignalPayload: Encodable {
+    @MainActor
     public static var parameters: [String: String] {
         var parameters: [String: String] = [
             // deprecated names
@@ -338,6 +339,7 @@ extension DefaultSignalPayload {
     }
 
     /// The current devices screen resolution width in points.
+    @MainActor
     static var screenResolutionWidth: String {
         #if os(iOS) || os(tvOS)
         return "\(UIScreen.main.bounds.width)"
@@ -354,6 +356,7 @@ extension DefaultSignalPayload {
     }
 
     /// The current devices screen resolution height in points.
+    @MainActor
     static var screenResolutionHeight: String {
         #if os(iOS) || os(tvOS)
         return "\(UIScreen.main.bounds.height)"
@@ -370,6 +373,7 @@ extension DefaultSignalPayload {
     }
 
     /// The current devices screen orientation. Returns `Fixed` for devices that don't support an orientation change.
+    @MainActor
     static var orientation: String {
         #if os(iOS)
         switch UIDevice.current.orientation {

Sources/TelemetryClient/SignalCache.swift

@@ -7,13 +7,13 @@ import Foundation
 /// correctly.
 ///
 /// Currently the cache is only in-memory. This will probably change in the near future.
-internal class SignalCache<T> where T: Codable {
+internal class SignalCache<T>: @unchecked Sendable where T: Codable {
     internal var logHandler: LogHandler?
 
     private var cachedSignals: [T] = []
     private let maximumNumberOfSignalsToPopAtOnce = 100
 
-    let queue = DispatchQueue(label: "telemetrydeck-signal-cache", attributes: .concurrent)
+    let queue = DispatchQueue(label: "com.telemetrydeck.SignalCache", attributes: .concurrent)
 
     /// How many Signals are cached
     func count() -> Int {

Sources/TelemetryClient/SignalEnricher.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-public protocol SignalEnricher {
+public protocol SignalEnricher: Sendable {
     func enrich(
         signalType: String,
         for clientUser: String?,

Sources/TelemetryClient/SignalManager.swift

@@ -15,11 +15,12 @@ internal protocol SignalManageable {
     func attemptToSendNextBatchOfCachedSignals()
 }
 
-internal class SignalManager: SignalManageable {
+internal final class SignalManager: SignalManageable, @unchecked Sendable {
     internal static let minimumSecondsToPassBetweenRequests: Double = 10
 
     private var signalCache: SignalCache<SignalPostBody>
     let configuration: TelemetryManagerConfiguration
+
     private var sendTimer: Timer?
 
     init(configuration: TelemetryManagerConfiguration) {
@@ -74,35 +75,41 @@ internal class SignalManager: SignalManageable {
         customUserID: String?,
         configuration: TelemetryManagerConfiguration
     ) {
-        DispatchQueue.global(qos: .utility).async {
-            let enrichedMetadata: [String: String] = configuration.metadataEnrichers
-                .map { $0.enrich(signalType: signalName, for: customUserID, floatValue: floatValue) }
-                .reduce([String: String](), { $0.applying($1) })
-
-            let payload = DefaultSignalPayload.parameters
-                .applying(enrichedMetadata)
-                .applying(parameters)
-
-            let signalPostBody = SignalPostBody(
-                receivedAt: Date(),
-                appID: UUID(uuidString: configuration.telemetryAppID)!,
-                clientUser: CryptoHashing.sha256(string: customUserID ?? self.defaultUserIdentifier, salt: configuration.salt),
-                sessionID: configuration.sessionID.uuidString,
-                type: "\(signalName)",
-                floatValue: floatValue,
-                payload: payload.toMultiValueDimension(),
-                isTestMode: configuration.testMode ? "true" : "false"
-            )
-
-            configuration.logHandler?.log(.debug, message: "Process signal: \(signalPostBody)")
-
-            self.signalCache.push(signalPostBody)
+        DispatchQueue.main.async {
+            let defaultUserIdentifier = self.defaultUserIdentifier
+            let defaultParameters = DefaultSignalPayload.parameters
+
+            DispatchQueue.global(qos: .utility).async {
+                let enrichedMetadata: [String: String] = configuration.metadataEnrichers
+                    .map { $0.enrich(signalType: signalName, for: customUserID, floatValue: floatValue) }
+                    .reduce([String: String](), { $0.applying($1) })
+
+                let payload = defaultParameters
+                    .applying(enrichedMetadata)
+                    .applying(parameters)
+
+                let signalPostBody = SignalPostBody(
+                    receivedAt: Date(),
+                    appID: UUID(uuidString: configuration.telemetryAppID)!,
+                    clientUser: CryptoHashing.sha256(string: customUserID ?? defaultUserIdentifier, salt: configuration.salt),
+                    sessionID: configuration.sessionID.uuidString,
+                    type: "\(signalName)",
+                    floatValue: floatValue,
+                    payload: payload.toMultiValueDimension(),
+                    isTestMode: configuration.testMode ? "true" : "false"
+                )
+
+                configuration.logHandler?.log(.debug, message: "Process signal: \(signalPostBody)")
+
+                self.signalCache.push(signalPostBody)
+            }
         }
     }
 
     /// Sends one batch of signals from the cache if not empty.
     /// If signals fail to send, we put them back into the cache to try again later.
     @objc
+    @Sendable
     internal func attemptToSendNextBatchOfCachedSignals() {
         configuration.logHandler?.log(.debug, message: "Current signal cache count: \(signalCache.count())")
 
@@ -175,7 +182,7 @@ private extension SignalManager {
 // MARK: - Comms
 
 private extension SignalManager {
-    private func send(_ signalPostBodies: [SignalPostBody], completionHandler: @escaping (Data?, URLResponse?, Error?) -> Void) {
+    private func send(_ signalPostBodies: [SignalPostBody], completionHandler: @escaping @Sendable (Data?, URLResponse?, Error?) -> Void) {
         DispatchQueue.global(qos: .utility).async {
             let path = "/api/v1/apps/\(self.configuration.telemetryAppID)/signals/multiple/"
             let url = self.configuration.apiBaseURL.appendingPathComponent(path)
@@ -209,6 +216,7 @@ private extension SignalManager {
     #endif
 
     /// The default user identifier. If the platform supports it, the ``identifierForVendor``. Otherwise, a self-generated `UUID` which is persisted in custom `UserDefaults` if available.
+    @MainActor
     var defaultUserIdentifier: String {
         guard configuration.defaultUser == nil else { return configuration.defaultUser! }