code clean up

.swiftformat

@@ -10,7 +10,7 @@
   --elseposition same-line
 
 --enable fileHeader
-  --header "//\n// Copyright 2018-{created.year} Amazon.com,\n// Inc. or its affiliates. All Rights Reserved.\n//\n// SPDX-License-Identifier: Apache-2.0\n//"
+  --header "//\n// Copyright 2018-2021 Amazon.com,\n// Inc. or its affiliates. All Rights Reserved.\n//\n// SPDX-License-Identifier: Apache-2.0\n//"
 
 --disable hoistPatternLet
   --patternlet inline

AppSyncRealTimeClient.xcodeproj/project.pbxproj

@@ -42,6 +42,9 @@
 		217F39F12406EA4000F1A0B3 /* MockConnectionProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 217F39EB2406EA3F00F1A0B3 /* MockConnectionProvider.swift */; };
 		217F39F22406EA4000F1A0B3 /* ConnectionProviderTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 217F39ED2406EA4000F1A0B3 /* ConnectionProviderTests.swift */; };
 		217F39F32406EA4000F1A0B3 /* RealtimeGatewayURLInterceptorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 217F39EF2406EA4000F1A0B3 /* RealtimeGatewayURLInterceptorTests.swift */; };
+		219BFF3B27A38902000FC148 /* schema.graphql in Resources */ = {isa = PBXBuildFile; fileRef = 219BFF3A27A38902000FC148 /* schema.graphql */; };
+		219BFF4927A3B238000FC148 /* ConnectivityMonitor.swift in Sources */ = {isa = PBXBuildFile; fileRef = 219BFF4827A3B237000FC148 /* ConnectivityMonitor.swift */; };
+		219BFF4B27A3B24F000FC148 /* ConnectivityPath.swift in Sources */ = {isa = PBXBuildFile; fileRef = 219BFF4A27A3B24F000FC148 /* ConnectivityPath.swift */; };
 		21D38B412409AFBD00EC2A8D /* AppSyncRealTimeClientIntegrationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 21D38B402409AFBD00EC2A8D /* AppSyncRealTimeClientIntegrationTests.swift */; };
 		21D38B432409AFBD00EC2A8D /* AppSyncRealTimeClient.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 217F398F2405D9D500F1A0B3 /* AppSyncRealTimeClient.framework */; };
 		21D38B4C2409B6C000EC2A8D /* amplifyconfiguration.json in Resources */ = {isa = PBXBuildFile; fileRef = 21D38B4B2409B6C000EC2A8D /* amplifyconfiguration.json */; };
@@ -159,6 +162,9 @@
 		217F39EB2406EA3F00F1A0B3 /* MockConnectionProvider.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MockConnectionProvider.swift; sourceTree = "<group>"; };
 		217F39ED2406EA4000F1A0B3 /* ConnectionProviderTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ConnectionProviderTests.swift; sourceTree = "<group>"; };
 		217F39EF2406EA4000F1A0B3 /* RealtimeGatewayURLInterceptorTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RealtimeGatewayURLInterceptorTests.swift; sourceTree = "<group>"; };
+		219BFF3A27A38902000FC148 /* schema.graphql */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = schema.graphql; sourceTree = "<group>"; };
+		219BFF4827A3B237000FC148 /* ConnectivityMonitor.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConnectivityMonitor.swift; sourceTree = "<group>"; };
+		219BFF4A27A3B24F000FC148 /* ConnectivityPath.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConnectivityPath.swift; sourceTree = "<group>"; };
 		21D38B3E2409AFBD00EC2A8D /* AppSyncRealTimeClientIntegrationTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = AppSyncRealTimeClientIntegrationTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		21D38B402409AFBD00EC2A8D /* AppSyncRealTimeClientIntegrationTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppSyncRealTimeClientIntegrationTests.swift; sourceTree = "<group>"; };
 		21D38B422409AFBD00EC2A8D /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
@@ -292,9 +298,10 @@
 		217F39912405D9D500F1A0B3 /* AppSyncRealTimeClient */ = {
 			isa = PBXGroup;
 			children = (
-				217F39932405D9D500F1A0B3 /* Info.plist */,
 				217F39B82406E98300F1A0B3 /* Connection */,
 				217F39A92406E98300F1A0B3 /* ConnectionProvider */,
+				219BFF4727A3B223000FC148 /* ConnectivityMonitor */,
+				217F39932405D9D500F1A0B3 /* Info.plist */,
 				21D38B6E240A272F00EC2A8D /* Interceptor */,
 				217F39C62406E98400F1A0B3 /* Support */,
 				217F39C12406E98400F1A0B3 /* Websocket */,
@@ -437,6 +444,15 @@
 			path = Support;
 			sourceTree = "<group>";
 		};
+		219BFF4727A3B223000FC148 /* ConnectivityMonitor */ = {
+			isa = PBXGroup;
+			children = (
+				219BFF4827A3B237000FC148 /* ConnectivityMonitor.swift */,
+				219BFF4A27A3B24F000FC148 /* ConnectivityPath.swift */,
+			);
+			path = ConnectivityMonitor;
+			sourceTree = "<group>";
+		};
 		21D38B3F2409AFBD00EC2A8D /* AppSyncRealTimeClientIntegrationTests */ = {
 			isa = PBXGroup;
 			children = (
@@ -497,6 +513,7 @@
 		21D38B95240C4DC200EC2A8D /* Support */ = {
 			isa = PBXGroup;
 			children = (
+				219BFF3A27A38902000FC148 /* schema.graphql */,
 				21D38B98240C4E1C00EC2A8D /* ConfigurationHelper.swift */,
 				21D38B96240C4DCF00EC2A8D /* Error+Extension.swift */,
 				21D38B9C240C540D00EC2A8D /* TestCommonConstants.swift */,
@@ -753,6 +770,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				21D38B4E2409B8B200EC2A8D /* README.md in Resources */,
+				219BFF3B27A38902000FC148 /* schema.graphql in Resources */,
 				21D38B4C2409B6C000EC2A8D /* amplifyconfiguration.json in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -1103,6 +1121,7 @@
 				217F39CD2406E98400F1A0B3 /* InterceptableConnection.swift in Sources */,
 				21D38B8E240A3C2300EC2A8D /* ConnectionProviderFactory.swift in Sources */,
 				217F39E02406E98400F1A0B3 /* AppSyncWebsocketProvider.swift in Sources */,
+				219BFF4927A3B238000FC148 /* ConnectivityMonitor.swift in Sources */,
 				FAB7E91224D2644E00DF1EA1 /* RealtimeConnectionProvider+StaleConnection.swift in Sources */,
 				217F39D32406E98400F1A0B3 /* RealtimeConnectionProvider.swift in Sources */,
 				217F39D12406E98400F1A0B3 /* AppSyncConnectionRequest.swift in Sources */,
@@ -1126,6 +1145,7 @@
 				217F39D42406E98400F1A0B3 /* RealtimeConnectionProvider+Websocket.swift in Sources */,
 				217F39DC2406E98400F1A0B3 /* AppSyncSubscriptionConnection.swift in Sources */,
 				21D38B6D240A262800EC2A8D /* AppSyncJSONHelper.swift in Sources */,
+				219BFF4B27A3B24F000FC148 /* ConnectivityPath.swift in Sources */,
 				217F39CE2406E98400F1A0B3 /* ConnectionProviderError.swift in Sources */,
 				217F39E12406E98400F1A0B3 /* StarscreamAdapter.swift in Sources */,
 				217F39D72406E98400F1A0B3 /* RealtimeConnectionProvider+ConnectionInterceptable.swift in Sources */,

AppSyncRealTimeClient.xcodeproj/xcshareddata/xcschemes/AppSyncRealTimeClient.xcscheme

@@ -45,6 +45,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      enableThreadSanitizer = "YES"
       launchStyle = "0"
       useCustomWorkingDirectory = "NO"
       ignoresPersistentStateOnLaunch = "NO"

AppSyncRealTimeClient/ConnectionProvider/AppsyncRealtimeConnection/RealtimeConnectionProvider+StaleConnection.swift

@@ -33,6 +33,28 @@ extension RealtimeConnectionProvider {
         staleConnectionTimer?.resetCountdown()
     }
 
+    /// Handle updates from the ConnectivityMonitor
+    func handleConnectivityUpdates(connectivity: ConnectivityPath) {
+        connectionQueue.async {[weak self] in
+            guard let self = self else {
+                return
+            }
+            AppSyncLogger.debug("[RealtimeConnectionProvider] Status: \(self.status). Connectivity status: \(connectivity.status)")
+            if self.status == .connected && connectivity.status == .unsatisfied && !self.isStaleConnection {
+                AppSyncLogger.debug("[RealtimeConnectionProvider] Connetion is stale. Pending reconnect on connectivity.")
+                self.isStaleConnection = true
+
+            } else if self.status == .connected && self.isStaleConnection && connectivity.status == .satisfied {
+                AppSyncLogger.debug("[RealtimeConnectionProvider] Connetion is stale. Disconnecting to begin reconnect.")
+                if self.staleConnectionTimer != nil {
+                    self.stopStaleConnectionTimer()
+                }
+
+                self.disconnectStaleConnection()
+            }
+        }
+    }
+
     /// Fired when the stale connection timer expires
     private func disconnectStaleConnection() {
         connectionQueue.async {[weak self] in
@@ -41,9 +63,9 @@ extension RealtimeConnectionProvider {
             }
             AppSyncLogger.error("[RealtimeConnectionProvider] Realtime connection is stale, disconnecting.")
             self.status = .notConnected
+            self.isStaleConnection = false
             self.websocket.disconnect()
             self.updateCallback(event: .error(ConnectionProviderError.connection))
         }
     }
-
 }

AppSyncRealTimeClient/ConnectionProvider/AppsyncRealtimeConnection/RealtimeConnectionProvider.swift

@@ -28,12 +28,18 @@ public class RealtimeConnectionProvider: ConnectionProvider {
     /// alive" message will cause the timer to be reset to the full interval.
     var staleConnectionTimer: CountdownTimer?
 
+    /// Intermediate state when the connection is connected and connectivity updates to unsatisfied (offline)
+    var isStaleConnection: Bool
+
     /// Manages concurrency for socket connections, disconnections, writes, and status reports.
     ///
     /// Each connection request will be sent to this queue. Connection request are
     /// handled one at a time.
     let connectionQueue: DispatchQueue
 
+    /// Monitor for connectivity updates to disconnect the current connection if it flips between connectivity statuses
+    let connectivityMonitor: ConnectivityMonitor
+
     /// The serial queue on which status & message callbacks from the web socket are invoked.
     private let serialCallbackQueue = DispatchQueue(
         label: "com.amazonaws.AppSyncRealTimeConnectionProvider.callbackQueue"
@@ -51,6 +57,9 @@ public class RealtimeConnectionProvider: ConnectionProvider {
         self.connectionQueue = DispatchQueue(
             label: "com.amazonaws.AppSyncRealTimeConnectionProvider.serialQueue"
         )
+        self.isStaleConnection = false
+        self.connectivityMonitor = ConnectivityMonitor()
+        connectivityMonitor.start(connectivityUpdates: handleConnectivityUpdates(connectivity:))
     }
 
     // MARK: - ConnectionProvider methods

AppSyncRealTimeClient/ConnectivityMonitor/ConnectivityMonitor.swift

@@ -0,0 +1,95 @@
+//
+// Copyright 2018-2021 Amazon.com,
+// Inc. or its affiliates. All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import Foundation
+import Network
+
+typealias ConnectivityUpdates = (ConnectivityPath) -> Void
+
+protocol AnyConnectivityMonitor {
+    func start(connectivityUpdatesQueue: DispatchQueue, onConnectivityUpdates: @escaping ConnectivityUpdates)
+    func cancel()
+}
+
+class ConnectivityMonitor {
+    var connectivity: ConnectivityPath?
+
+    private let connectivityUpdatesQueue = DispatchQueue(
+        label: "com.amazonaws.ConnectivityMonitor.connectivityUpdatesQueue",
+        qos: .background
+    )
+    private var monitor: AnyConnectivityMonitor?
+
+    init(connectivityMonitor: AnyConnectivityMonitor? = nil) {
+        self.monitor = connectivityMonitor
+    }
+
+    func start(connectivityUpdates: @escaping ConnectivityUpdates) {
+        if let monitor = monitor {
+            monitor.start(
+                connectivityUpdatesQueue: connectivityUpdatesQueue,
+                onConnectivityUpdates: connectivityUpdates
+            )
+        } else if #available(iOS 12.0, *) {
+            let monitor = NetworkMonitor()
+            self.monitor = monitor
+            monitor.start(
+                connectivityUpdatesQueue: connectivityUpdatesQueue,
+                onConnectivityUpdates: connectivityUpdates
+            )
+        }
+    }
+
+    func cancel() {
+        guard let monitor = monitor else {
+            return
+        }
+        monitor.cancel()
+        self.monitor = nil
+    }
+
+    deinit {
+        cancel()
+    }
+}
+
+@available(iOS 12.0, macOS 10.14, tvOS 12.0, watchOS 6.0, *)
+class NetworkMonitor: AnyConnectivityMonitor {
+    private var monitor: NWPathMonitor?
+    private var onConnectivityUpdates: ConnectivityUpdates?
+    private var connectivityUpdatesQueue: DispatchQueue?
+    private let queue = DispatchQueue(label: "com.amazonaws.NetworkMonitor.queue", qos: .background)
+
+    func start(connectivityUpdatesQueue: DispatchQueue, onConnectivityUpdates: @escaping ConnectivityUpdates) {
+        self.connectivityUpdatesQueue = connectivityUpdatesQueue
+        self.onConnectivityUpdates = onConnectivityUpdates
+        // A new instance is required each time a monitor is started
+        let monitor = NWPathMonitor()
+        monitor.pathUpdateHandler = didUpdate(path:)
+        monitor.start(queue: queue)
+        self.monitor = monitor
+    }
+
+    func cancel() {
+        guard let monitor = monitor else { return }
+        defer {
+            self.monitor = nil
+        }
+        monitor.cancel()
+    }
+
+    func didUpdate(path: NWPath) {
+        guard let onConnectivityUpdates = onConnectivityUpdates,
+              let connectivityUpdatesQueue = connectivityUpdatesQueue else {
+            return
+        }
+        let connectivityPath = ConnectivityPath(path: path)
+        connectivityUpdatesQueue.async {
+            onConnectivityUpdates(connectivityPath)
+        }
+    }
+}

AppSyncRealTimeClient/ConnectivityMonitor/ConnectivityPath.swift

@@ -0,0 +1,125 @@
+//
+// Copyright 2018-2021 Amazon.com,
+// Inc. or its affiliates. All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import Foundation
+import Network
+
+struct ConnectivityPath {
+    let status: ConnectivityStatus
+    let availableInterfaces: [ConnectivityInterface]
+    let isExpensive: Bool
+    let supportsDNS: Bool
+    let supportsIPv4: Bool
+    let supportsIPv6: Bool
+
+    init(
+        status: ConnectivityStatus = .unsatisfied,
+        availableInterfaces: [ConnectivityInterface] = [],
+        isExpensive: Bool = false,
+        supportsDNS: Bool = false,
+        supportsIPv4: Bool = false,
+        supportsIPv6: Bool = false
+    ) {
+        self.status = status
+        self.availableInterfaces = availableInterfaces
+        self.isExpensive = isExpensive
+        self.supportsDNS = supportsDNS
+        self.supportsIPv4 = supportsIPv4
+        self.supportsIPv6 = supportsIPv6
+    }
+}
+
+extension ConnectivityPath: CustomStringConvertible {
+    var description: String {
+        [
+            "\(status): \(availableInterfaces.description)",
+            "Expensive = \(isExpensive ? "YES" : "NO")",
+            "DNS = \(supportsDNS ? "YES" : "NO")",
+            "IPv4 = \(supportsIPv4 ? "YES" : "NO")",
+            "IPv6 = \(supportsIPv6 ? "YES" : "NO")"
+        ].joined(separator: "; ")
+    }
+}
+
+extension ConnectivityPath {
+    @available(iOS 12.0, *)
+    init(path: NWPath) {
+        self.status = ConnectivityStatus(status: path.status)
+        self.availableInterfaces = path.availableInterfaces.map { ConnectivityInterface(interface: $0) }
+        self.isExpensive = path.isExpensive
+        self.supportsDNS = path.supportsDNS
+        self.supportsIPv4 = path.supportsIPv4
+        self.supportsIPv6 = path.supportsIPv6
+    }
+}
+
+enum ConnectivityInterfaceType: String {
+    case other
+    case wifi
+    case cellular
+    case wiredEthernet
+    case loopback
+}
+
+extension ConnectivityInterfaceType {
+    @available(iOS 12.0, *)
+    init(interfaceType: NWInterface.InterfaceType) {
+        switch interfaceType {
+        case .other:
+            self = .other
+        case .wifi:
+            self = .wifi
+        case .cellular:
+            self = .cellular
+        case .wiredEthernet:
+            self = .wiredEthernet
+        case .loopback:
+            self = .loopback
+        @unknown default:
+            self = .other
+        }
+    }
+}
+
+struct ConnectivityInterface {
+    public let name: String
+    public let type: ConnectivityInterfaceType
+
+    public init(name: String, type: ConnectivityInterfaceType) {
+        self.name = name
+        self.type = type
+    }
+}
+extension ConnectivityInterface {
+    @available(iOS 12.0, *)
+    init(interface: NWInterface) {
+        self.name = interface.name
+        self.type = ConnectivityInterfaceType(interfaceType: interface.type)
+    }
+}
+
+enum ConnectivityStatus: String {
+    case satisfied
+    case unsatisfied
+    case requiresConnection
+}
+
+extension ConnectivityStatus {
+    @available(iOS 12.0, *)
+    init(status: NWPath.Status) {
+        switch status {
+        case .satisfied:
+            self = .satisfied
+        case .unsatisfied:
+            self = .unsatisfied
+        case .requiresConnection:
+            self = .requiresConnection
+        @unknown default:
+            self = .unsatisfied
+        }
+    }
+}