feat(core): Make the ping manager optional

example/lib/main.dart

@@ -77,7 +77,9 @@ class _MyHomePageState extends State<MyHomePage> {
         StreamManagementManager(),
         DiscoManager([]),
         RosterManager(TestingRosterStateManager("", [])),
-        PingManager(),
+        PingManager(
+          const Duration(minutes: 3),
+        ),
         MessageManager(),
         PresenceManager(),
       ])

packages/moxxmpp/lib/src/connection.dart

@@ -83,7 +83,6 @@ class XmppConnection {
     ReconnectionPolicy reconnectionPolicy,
     ConnectivityManager connectivityManager,
     this._socket, {
-    this.connectionPingDuration = const Duration(minutes: 3),
     this.connectingTimeout = const Duration(minutes: 2),
   })  : _reconnectionPolicy = reconnectionPolicy,
         _connectivityManager = connectivityManager {
@@ -143,10 +142,6 @@ class XmppConnection {
   /// UUID object to generate stanza and origin IDs
   final Uuid _uuid = const Uuid();
 
-  /// The time between sending a ping to keep the connection open
-  // TODO(Unknown): Only start the timer if we did not send a stanza after n seconds
-  final Duration connectionPingDuration;
-
   /// The time that we may spent in the "connecting" state
   final Duration connectingTimeout;
 
@@ -159,9 +154,6 @@ class XmppConnection {
   /// True if we are authenticated. False if not.
   bool _isAuthenticated = false;
 
-  /// Timer for the keep-alive ping.
-  Timer? _connectionPingTimer;
-
   /// Timer for the connecting timeout
   Timer? _connectingTimeoutTimer;
 
@@ -627,22 +619,7 @@ class XmppConnection {
     final oldState = _connectionState;
     _connectionState = state;
 
-    final sm = getNegotiatorById<StreamManagementNegotiator>(
-      streamManagementNegotiator,
-    );
-    await _sendEvent(
-      ConnectionStateChangedEvent(
-        state,
-        oldState,
-        sm?.isResumed ?? false,
-      ),
-    );
-
     if (state == XmppConnectionState.connected) {
-      _log.finest('Starting _pingConnectionTimer');
-      _connectionPingTimer =
-          Timer.periodic(connectionPingDuration, _pingConnectionOpen);
-
       // We are connected, so the timer can stop.
       _destroyConnectingTimer();
     } else if (state == XmppConnectionState.connecting) {
@@ -655,14 +632,18 @@ class XmppConnection {
     } else {
       // Just make sure the connecting timeout timer is not running
       _destroyConnectingTimer();
-
-      // The ping timer makes no sense if we are not connected
-      if (_connectionPingTimer != null) {
-        _log.finest('Destroying _pingConnectionTimer');
-        _connectionPingTimer!.cancel();
-        _connectionPingTimer = null;
-      }
     }
+
+    final sm = getNegotiatorById<StreamManagementNegotiator>(
+      streamManagementNegotiator,
+    );
+    await _sendEvent(
+      ConnectionStateChangedEvent(
+        state,
+        oldState,
+        sm?.isResumed ?? false,
+      ),
+    );
   }
 
   /// Sets the routing state and logs the change
@@ -682,22 +663,6 @@ class XmppConnection {
     return _eventStreamController.stream.asBroadcastStream();
   }
 
-  /// Timer callback to prevent the connection from timing out.
-  Future<void> _pingConnectionOpen(Timer timer) async {
-    // Follow the recommendation of XEP-0198 and just request an ack. If SM is not enabled,
-    // send a whitespace ping
-    _log.finest('_pingConnectionTimer: Callback called.');
-
-    if (_connectionState == XmppConnectionState.connected) {
-      _log.finest('_pingConnectionTimer: Connected. Triggering a ping event.');
-      unawaited(_sendEvent(SendPingEvent()));
-    } else {
-      _log.finest(
-        '_pingConnectionTimer: Not connected. Not triggering an event.',
-      );
-    }
-  }
-
   /// Iterate over [handlers] and check if the handler matches [stanza]. If it does,
   /// call its callback and end the processing if the callback returned true; continue
   /// if it returned false.
@@ -1130,10 +1095,6 @@ class XmppConnection {
       _xmppManagers.containsKey(discoManager),
       'A DiscoManager is mandatory',
     );
-    assert(
-      _xmppManagers.containsKey(pingManager),
-      'A PingManager is mandatory',
-    );
   }
 
   /// The private implementation for [XmppConnection.connect]. The parameters have

packages/moxxmpp/lib/src/events.dart

@@ -26,6 +26,12 @@ class ConnectionStateChangedEvent extends XmppEvent {
   final XmppConnectionState before;
   final XmppConnectionState state;
   final bool resumed;
+
+  /// Indicates whether the connection state switched from a not connected state to a
+  /// connected state.
+  bool get connectionEstablished =>
+      before != XmppConnectionState.connected &&
+      state == XmppConnectionState.connected;
 }
 
 /// Triggered when we encounter a stream error.

packages/moxxmpp/lib/src/ping.dart

@@ -1,10 +1,23 @@
+import 'dart:async';
+import 'package:meta/meta.dart';
 import 'package:moxxmpp/src/events.dart';
 import 'package:moxxmpp/src/managers/base.dart';
 import 'package:moxxmpp/src/managers/namespaces.dart';
 import 'package:moxxmpp/src/xeps/xep_0198/xep_0198.dart';
+import 'package:synchronized/synchronized.dart';
 
+/// This manager class is responsible to sending periodic pings, if required, using
+/// either whitespaces or Stream Management. Keep in mind, that without
+/// Stream Management, a stale connection cannot be detected.
 class PingManager extends XmppManagerBase {
-  PingManager() : super(pingManager);
+  PingManager(this._pingDuration) : super(pingManager);
+
+  /// The time between pings, when connected.
+  final Duration _pingDuration;
+
+  /// The actual timer.
+  Timer? _pingTimer;
+  final Lock _timerLock = Lock();
 
   @override
   Future<bool> isSupported() async => true;
@@ -15,39 +28,73 @@ class PingManager extends XmppManagerBase {
     );
   }
 
+  /// Cancel a potentially scheduled ping timer. Can be overriden to cancel a custom timing mechanism.
+  /// By default, cancels a [Timer.periodic] that was set up prior.
+  @visibleForOverriding
+  Future<void> cancelPing() async {
+    await _timerLock.synchronized(() {
+      logger.finest('Cancelling timer');
+      _pingTimer?.cancel();
+      _pingTimer = null;
+    });
+  }
+
+  /// Schedule a ping to be sent after a given amount of time. Can be overriden for custom timing mechanisms.
+  /// By default, uses a [Timer.periodic] timer to trigger a ping.
+  /// NOTE: This function is called whenever the connection is re-established. Custom
+  ///       implementations should thus guard against multiple timers being started.
+  @visibleForOverriding
+  Future<void> schedulePing() async {
+    await _timerLock.synchronized(() {
+      logger.finest('Scheduling new timer? ${_pingTimer != null}');
+
+      _pingTimer ??= Timer.periodic(
+        _pingDuration,
+        _sendPing,
+      );
+    });
+  }
+
+  Future<void> _sendPing(Timer _) async {
+    logger.finest('Attempting to send ping');
+    final attrs = getAttributes();
+    final socket = attrs.getSocket();
+
+    if (socket.managesKeepalives()) {
+      logger.finest('Not sending ping as the socket manages it.');
+      return;
+    }
+
+    final stream = attrs.getManagerById(smManager) as StreamManagementManager?;
+    if (stream != null) {
+      if (stream
+          .isStreamManagementEnabled() /*&& stream.getUnackedStanzaCount() > 0*/) {
+        logger.finest('Sending an ack ping as Stream Management is enabled');
+        stream.sendAckRequestPing();
+      } else if (attrs.getSocket().whitespacePingAllowed()) {
+        logger.finest(
+          'Sending a whitespace ping as Stream Management is not enabled',
+        );
+        attrs.getConnection().sendWhitespacePing();
+      } else {
+        _logWarning();
+      }
+    } else {
+      if (attrs.getSocket().whitespacePingAllowed()) {
+        attrs.getConnection().sendWhitespacePing();
+      } else {
+        _logWarning();
+      }
+    }
+  }
+
   @override
   Future<void> onXmppEvent(XmppEvent event) async {
-    if (event is SendPingEvent) {
+    if (event is ConnectionStateChangedEvent) {
-      logger.finest('Received ping event.');
+      if (event.connectionEstablished) {
-      final attrs = getAttributes();
+        await schedulePing();
-      final socket = attrs.getSocket();
-
-      if (socket.managesKeepalives()) {
-        logger.finest('Not sending ping as the socket manages it.');
-        return;
-      }
-
-      final stream =
-          attrs.getManagerById(smManager) as StreamManagementManager?;
-      if (stream != null) {
-        if (stream
-            .isStreamManagementEnabled() /*&& stream.getUnackedStanzaCount() > 0*/) {
-          logger.finest('Sending an ack ping as Stream Management is enabled');
-          stream.sendAckRequestPing();
-        } else if (attrs.getSocket().whitespacePingAllowed()) {
-          logger.finest(
-            'Sending a whitespace ping as Stream Management is not enabled',
-          );
-          attrs.getConnection().sendWhitespacePing();
-        } else {
-          _logWarning();
-        }
       } else {
-        if (attrs.getSocket().whitespacePingAllowed()) {
+        await cancelPing();
-          attrs.getConnection().sendWhitespacePing();
-        } else {
-          _logWarning();
-        }
       }
     }
   }

packages/moxxmpp/test/negotiator_test.dart

@@ -75,7 +75,6 @@ void main() {
       PresenceManager(),
       RosterManager(TestingRosterStateManager('', [])),
       DiscoManager([]),
-      PingManager(),
       EntityCapabilitiesManager('http://moxxmpp.example'),
     ])
     ..setConnectionSettings(

packages/moxxmpp/test/xeps/xep_0030_test.dart

@@ -82,7 +82,6 @@ void main() {
       PresenceManager(),
       RosterManager(TestingRosterStateManager(null, [])),
       DiscoManager([]),
-      PingManager(),
       EntityCapabilitiesManager('http://moxxmpp.example'),
     ]);
     conn.registerFeatureNegotiators([

packages/moxxmpp/test/xeps/xep_0060_test.dart

@@ -168,7 +168,6 @@ void main() {
       PresenceManager(),
       MessageManager(),
       RosterManager(TestingRosterStateManager(null, [])),
-      PingManager(),
     ]);
     connection
       ..registerFeatureNegotiators([

packages/moxxmpp/test/xeps/xep_0198_test.dart

@@ -294,7 +294,6 @@ void main() {
         PresenceManager(),
         RosterManager(TestingRosterStateManager('', [])),
         DiscoManager([]),
-        PingManager(),
         sm,
         CarbonsManager()..forceEnable(),
         EntityCapabilitiesManager('http://moxxmpp.example'),
@@ -420,7 +419,6 @@ void main() {
         PresenceManager(),
         RosterManager(TestingRosterStateManager('', [])),
         DiscoManager([]),
-        PingManager(),
         sm,
         CarbonsManager()..forceEnable(),
         //EntityCapabilitiesManager('http://moxxmpp.example'),
@@ -580,7 +578,6 @@ void main() {
         PresenceManager(),
         RosterManager(TestingRosterStateManager('', [])),
         DiscoManager([]),
-        PingManager(),
         StreamManagementManager(),
       ]);
       conn.registerFeatureNegotiators([
@@ -675,7 +672,6 @@ void main() {
         PresenceManager(),
         RosterManager(TestingRosterStateManager('', [])),
         DiscoManager([]),
-        PingManager(),
         StreamManagementManager(),
       ]);
       conn.registerFeatureNegotiators([
@@ -767,7 +763,6 @@ void main() {
         PresenceManager(),
         RosterManager(TestingRosterStateManager('', [])),
         DiscoManager([]),
-        PingManager(),
         StreamManagementManager(),
       ]);
       conn.registerFeatureNegotiators([

packages/moxxmpp/test/xmpp_test.dart

@@ -137,7 +137,6 @@ void main() {
       PresenceManager(),
       RosterManager(TestingRosterStateManager('', [])),
       DiscoManager([]),
-      PingManager(),
       StreamManagementManager(),
       EntityCapabilitiesManager('http://moxxmpp.example'),
     ]);
@@ -194,7 +193,6 @@ void main() {
       PresenceManager(),
       RosterManager(TestingRosterStateManager('', [])),
       DiscoManager([]),
-      PingManager(),
       EntityCapabilitiesManager('http://moxxmpp.example'),
     ]);
     conn.registerFeatureNegotiators([
@@ -254,7 +252,6 @@ void main() {
       PresenceManager(),
       RosterManager(TestingRosterStateManager('', [])),
       DiscoManager([]),
-      PingManager(),
       EntityCapabilitiesManager('http://moxxmpp.example'),
     ]);
     conn.registerFeatureNegotiators([SaslPlainNegotiator()]);
@@ -409,7 +406,6 @@ void main() {
       PresenceManager(),
       RosterManager(TestingRosterStateManager('', [])),
       DiscoManager([]),
-      PingManager(),
     ]);
     conn
       ..registerFeatureNegotiators([