fix(database, web): ensure exact same streams are not unsubscribed in debug mode (#13029)

Author: russellwheatley

packages/firebase_database/firebase_database_web/lib/src/interop/database.dart

@@ -250,18 +250,18 @@ class Query<T extends database_interop.QueryJsImpl> extends JsObjectWrapper<T> {
   /// DatabaseReference to the Query's location.
   DatabaseReference get ref => DatabaseReference.getInstance(jsObject.ref);
 
-  Stream<QueryEvent> _onValue(String appName, int hashCode) => _createStream(
+  Stream<QueryEvent> _onValue(String appName, String hashCode) => _createStream(
         'value',
         appName,
         hashCode,
       );
 
   /// Stream for a value event. Event is triggered once with the initial
   /// data stored at location, and then again each time the data changes.
-  Stream<QueryEvent> onValue(String appName, int hashCode) =>
+  Stream<QueryEvent> onValue(String appName, String hashCode) =>
       _onValue(appName, hashCode);
 
-  Stream<QueryEvent> _onChildAdded(String appName, int hashCode) =>
+  Stream<QueryEvent> _onChildAdded(String appName, String hashCode) =>
       _createStream(
         'child_added',
         appName,
@@ -270,10 +270,10 @@ class Query<T extends database_interop.QueryJsImpl> extends JsObjectWrapper<T> {
 
   /// Stream for a child_added event. Event is triggered once for each
   /// initial child at location, and then again every time a new child is added.
-  Stream<QueryEvent> onChildAdded(String appName, int hashCode) =>
+  Stream<QueryEvent> onChildAdded(String appName, String hashCode) =>
       _onChildAdded(appName, hashCode);
 
-  Stream<QueryEvent> _onChildRemoved(String appName, int hashCode) =>
+  Stream<QueryEvent> _onChildRemoved(String appName, String hashCode) =>
       _createStream(
         'child_removed',
         appName,
@@ -282,10 +282,10 @@ class Query<T extends database_interop.QueryJsImpl> extends JsObjectWrapper<T> {
 
   /// Stream for a child_removed event. Event is triggered once every time
   /// a child is removed.
-  Stream<QueryEvent> onChildRemoved(String appName, int hashCode) =>
+  Stream<QueryEvent> onChildRemoved(String appName, String hashCode) =>
       _onChildRemoved(appName, hashCode);
 
-  Stream<QueryEvent> _onChildChanged(String appName, int hashCode) =>
+  Stream<QueryEvent> _onChildChanged(String appName, String hashCode) =>
       _createStream(
         'child_changed',
         appName,
@@ -295,9 +295,9 @@ class Query<T extends database_interop.QueryJsImpl> extends JsObjectWrapper<T> {
   /// Stream for a child_changed event. Event is triggered when the data
   /// stored in a child (or any of its descendants) changes.
   /// Single child_changed event may represent multiple changes to the child.
-  Stream<QueryEvent> onChildChanged(String appName, int hashCode) =>
+  Stream<QueryEvent> onChildChanged(String appName, String hashCode) =>
       _onChildChanged(appName, hashCode);
-  Stream<QueryEvent> _onChildMoved(String appName, int hashCode) =>
+  Stream<QueryEvent> _onChildMoved(String appName, String hashCode) =>
       _createStream(
         'child_moved',
         appName,
@@ -306,7 +306,7 @@ class Query<T extends database_interop.QueryJsImpl> extends JsObjectWrapper<T> {
 
   /// Stream for a child_moved event. Event is triggered when a child's priority
   /// changes such that its position relative to its siblings changes.
-  Stream<QueryEvent> onChildMoved(String appName, int hashCode) =>
+  Stream<QueryEvent> onChildMoved(String appName, String hashCode) =>
       _onChildMoved(appName, hashCode);
 
   /// Creates a new Query from a [jsObject].
@@ -403,13 +403,13 @@ class Query<T extends database_interop.QueryJsImpl> extends JsObjectWrapper<T> {
     );
   }
 
-  String _streamWindowsKey(String appName, String eventType, int hashCode) =>
+  String _streamWindowsKey(String appName, String eventType, String hashCode) =>
       'flutterfire-${appName}_${eventType}_${hashCode}_snapshot';
 
   Stream<QueryEvent> _createStream(
     String eventType,
     String appName,
-    int hashCode,
+    String hashCode,
   ) {
     late StreamController<QueryEvent> streamController;
     unsubscribeWindowsListener(_streamWindowsKey(appName, eventType, hashCode));

packages/firebase_database/firebase_database_web/lib/src/query_web.dart

@@ -64,6 +64,8 @@ class QueryWeb extends QueryPlatform {
     return instance;
   }
 
+  final Map<String, int> _streamHashCodeMap = {};
+
   @override
   String get path {
     final refPath = Uri.parse(_queryDelegate.ref.toString()).path;
@@ -89,26 +91,46 @@ class QueryWeb extends QueryPlatform {
     throw UnsupportedError('keepSynced() is not supported on web');
   }
 
-  @override
-  Stream<DatabaseEventPlatform> observe(
-      QueryModifiers modifiers, DatabaseEventType eventType) {
-    database_interop.Query instance = _getQueryDelegateInstance(modifiers);
-
-    int hashCode = 0;
-    final appName =
-        _database.app != null ? _database.app!.name : Firebase.app().name;
+  String _createHashCode(
+    QueryModifiers modifiers,
+    DatabaseEventType eventType,
+    String appName,
+  ) {
+    String hashCode = '0';
     if (kDebugMode) {
-      // Purely for unsubscribing purposes in debug mode on "hot restart"
-      // if not running in debug mode, hashCode won't be used
       hashCode = Object.hashAll([
         appName,
         path,
         ...modifiers
             .toList()
             .map((e) => const DeepCollectionEquality().hash(e)),
         eventType.index,
-      ]);
+      ]).toString();
+      // Need to track as the same properties to create hash could be used multiple times
+      if (_streamHashCodeMap.containsKey(hashCode)) {
+        int count = _streamHashCodeMap[hashCode] ?? 0;
+        final updatedCount = count + 1;
+        _streamHashCodeMap[hashCode] = updatedCount;
+        hashCode = '$hashCode-$updatedCount';
+      } else {
+        // initial stream
+        _streamHashCodeMap[hashCode] = 0;
+        hashCode = '$hashCode-0';
+      }
     }
+    return hashCode;
+  }
+
+  @override
+  Stream<DatabaseEventPlatform> observe(
+      QueryModifiers modifiers, DatabaseEventType eventType) {
+    database_interop.Query instance = _getQueryDelegateInstance(modifiers);
+    final appName =
+        _database.app != null ? _database.app!.name : Firebase.app().name;
+
+    // Purely for unsubscribing purposes in debug mode on "hot restart"
+    // if not running in debug mode, hashCode won't be used
+    String hashCode = _createHashCode(modifiers, eventType, appName);
 
     switch (eventType) {
       case DatabaseEventType.childAdded: