close chain height subscriptions on tor connection preference change

lib/electrumx_rpc/electrumx_chain_height_service.dart

@@ -5,35 +5,63 @@ import 'package:stackwallet/utilities/enums/coin_enum.dart';
 
 /// Manage chain height subscriptions for each coin.
 abstract class ChainHeightServiceManager {
+  // A map of chain height services for each coin.
   static final Map<Coin, ChainHeightService> _services = {};
+  // Map<Coin, ChainHeightService> get services => _services;
 
+  // Get the chain height service for a specific coin.
   static ChainHeightService? getService(Coin coin) {
     return _services[coin];
   }
 
+  // Add a chain height service for a specific coin.
   static void add(ChainHeightService service, Coin coin) {
+    // Don't add a new service if one already exists.
     if (_services[coin] == null) {
       _services[coin] = service;
     } else {
       throw Exception("Chain height service for $coin already managed");
     }
   }
+
+  // Remove a chain height service for a specific coin.
+  static void remove(Coin coin) {
+    _services.remove(coin);
+  }
+
+  // Close all subscriptions and clean up resources.
+  static Future<void> dispose() async {
+    // Close each subscription.
+    for (final coin in _services.keys) {
+      final ChainHeightService? service = getService(coin);
+      await service?.cancelListen();
+      remove(coin);
+    }
+  }
 }
 
-// Basic untested impl. Needs error handling and branching to handle
-// various other scenarios
+/// A service to fetch and listen for chain height updates.
+///
+/// TODO: Add error handling and branching to handle various other scenarios.
 class ChainHeightService {
+  // The electrum_adapter client to use for fetching chain height updates.
   ElectrumClient client;
 
+  // The subscription to listen for chain height updates.
   StreamSubscription<dynamic>? _subscription;
+
+  // Whether the service has started listening for updates.
   bool get started => _subscription != null;
 
+  // The current chain height.
   int? _height;
   int? get height => _height;
 
   ChainHeightService({required this.client});
 
+  /// Fetch the current chain height and start listening for updates.
   Future<int> fetchHeightAndStartListenForUpdates() async {
+    // Don't start a new subscription if one already exists.
     if (_subscription != null) {
       throw Exception(
         "Attempted to start a chain height service where an existing"
@@ -41,17 +69,22 @@ class ChainHeightService {
       );
     }
 
+    // A completer to wait for the current chain height to be fetched.
     final completer = Completer<int>();
-    _subscription = client.subscribeHeaders().listen((event) {
+
+    // Fetch the current chain height.
+    _subscription = client.subscribeHeaders().listen((BlockHeader event) {
       _height = event.height;
+
       if (!completer.isCompleted) {
         completer.complete(_height);
       }
     });
 
+    // Wait for the current chain height to be fetched.
     return completer.future;
   }
 
-  /// Untested/Unknown implications. USE AT OWN RISK
+  /// Stop listening for chain height updates.
   Future<void> cancelListen() async => await _subscription?.cancel();
 }

lib/electrumx_rpc/electrumx_client.dart

@@ -20,6 +20,7 @@ import 'package:event_bus/event_bus.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter_libsparkmobile/flutter_libsparkmobile.dart';
 import 'package:mutex/mutex.dart';
+import 'package:stackwallet/electrumx_rpc/electrumx_chain_height_service.dart';
 import 'package:stackwallet/electrumx_rpc/rpc.dart';
 import 'package:stackwallet/exceptions/electrumx/no_such_transaction.dart';
 import 'package:stackwallet/services/event_bus/events/global/tor_connection_status_changed_event.dart';
@@ -127,6 +128,8 @@ class ElectrumXClient {
     _coin = coin;
 
     final bus = globalEventBusForTesting ?? GlobalEventBus.instance;
+
+    // Listen for tor status changes.
     _torStatusListener = bus.on<TorConnectionStatusChangedEvent>().listen(
       (event) async {
         switch (event.newStatus) {
@@ -145,6 +148,8 @@ class ElectrumXClient {
         }
       },
     );
+
+    // Listen for tor preference changes.
     _torPreferenceListener = bus.on<TorPreferenceChangedEvent>().listen(
       (event) async {
         // not sure if we need to do anything specific here
@@ -157,6 +162,9 @@ class ElectrumXClient {
         // on the next request sent through this electrumx instance
         _electrumAdapterChannel = null;
         _electrumAdapterClient = null;
+
+        // Also close any chain height services that are currently open.
+        await ChainHeightServiceManager.dispose();
       },
     );
   }

lib/wallets/wallet/wallet_mixin_interfaces/electrumx_interface.dart

@@ -7,7 +7,6 @@ import 'package:coinlib_flutter/coinlib_flutter.dart' as coinlib;
 import 'package:electrum_adapter/electrum_adapter.dart' as electrum_adapter;
 import 'package:electrum_adapter/electrum_adapter.dart';
 import 'package:isar/isar.dart';
-import 'package:mutex/mutex.dart';
 import 'package:stackwallet/electrumx_rpc/cached_electrumx_client.dart';
 import 'package:stackwallet/electrumx_rpc/electrumx_chain_height_service.dart';
 import 'package:stackwallet/electrumx_rpc/electrumx_client.dart';
@@ -17,9 +16,6 @@ import 'package:stackwallet/models/isar/models/blockchain_data/v2/transaction_v2
 import 'package:stackwallet/models/isar/models/isar_models.dart';
 import 'package:stackwallet/models/paymint/fee_object_model.dart';
 import 'package:stackwallet/models/signing_data.dart';
-import 'package:stackwallet/services/event_bus/events/global/tor_connection_status_changed_event.dart';
-import 'package:stackwallet/services/event_bus/events/global/tor_status_changed_event.dart';
-import 'package:stackwallet/services/event_bus/global_event_bus.dart';
 import 'package:stackwallet/services/tor_service.dart';
 import 'package:stackwallet/utilities/amount/amount.dart';
 import 'package:stackwallet/utilities/enums/coin_enum.dart';
@@ -42,17 +38,10 @@ mixin ElectrumXInterface<T extends Bip39HDCurrency> on Bip39HDWallet<T> {
   late ElectrumClient electrumAdapterClient;
   late CachedElectrumXClient electrumXCachedClient;
   // late SubscribableElectrumXClient subscribableElectrumXClient;
+  late ChainHeightServiceManager chainHeightServiceManager;
 
   int? get maximumFeerate => null;
 
-  StreamSubscription<TorPreferenceChangedEvent>? _torPreferenceListener;
-  StreamSubscription<TorConnectionStatusChangedEvent>? _torStatusListener;
-  final Mutex _torConnectingLock = Mutex();
-  bool _requireMutex = false;
-  Timer? _aliveTimer;
-  static const Duration _keepAlive = Duration(minutes: 1);
-  bool _isConnected = false;
-
   static const _kServerBatchCutoffVersion = [1, 6];
   List<int>? _serverVersion;
   bool get serverCanBatch {
@@ -819,19 +808,23 @@ mixin ElectrumXInterface<T extends Bip39HDCurrency> on Bip39HDWallet<T> {
 
   Future<int> fetchChainHeight() async {
     try {
+      // Get the chain height service for the current coin.
       ChainHeightService? service = ChainHeightServiceManager.getService(
         cryptoCurrency.coin,
       );
 
+      // ... or create a new one if it doesn't exist.
       if (service == null) {
         service = ChainHeightService(client: electrumAdapterClient);
         ChainHeightServiceManager.add(service, cryptoCurrency.coin);
       }
 
+      // If the service hasn't been started, start it and fetch the chain height.
       if (!service.started) {
         return await service.fetchHeightAndStartListenForUpdates();
       }
 
+      // Return the height as per the service if available or the cached height.
       return service.height ?? info.cachedChainHeight;
     } catch (e, s) {
       Logging.instance.log(
@@ -959,15 +952,6 @@ mixin ElectrumXInterface<T extends Bip39HDCurrency> on Bip39HDWallet<T> {
     //     host: newNode.address, port: newNode.port);
   }
 
-  /// Update the connection status and call the onConnectionStatusChanged callback if it exists.
-  void _updateConnectionStatus(bool connectionStatus) {
-    // TODO [prio=low]: Set onConnectionStatusChanged callback.
-    // if (_isConnected != connectionStatus && onConnectionStatusChanged != null) {
-    //   onConnectionStatusChanged!(connectionStatus);
-    // }
-    _isConnected = connectionStatus;
-  }
-
   //============================================================================
 
   Future<({List<Address> addresses, int index})> checkGapsBatched(