Protect from identityHashCode equal to 0. (#90)

doc/TROUBLESHOOT.md

@@ -82,8 +82,9 @@ if (ref.target == null) {
 ```
 
 IMPORTANT: this code will not work in release mode, so
-you need to run it with flag `--debug` or `--profile`, or,
-if it is test, by clicking `Debug` near your test name in IDE.
+you need to run it with flag `--debug` or `--profile`
+([not available](https://github.com/flutter/flutter/issues/127331) for Flutter tests),
+or, if it is a test, by clicking `Debug` near the test name in IDE.
 
 ## Known complicated cases
 

pkgs/leak_tracker/CHANGELOG.md

@@ -1,3 +1,7 @@
+# 7.0.7
+
+* Protect from identityHashCode equal to 0.
+
 # 7.0.6
 
 * Add helpers for troubleshooting.

pkgs/leak_tracker/lib/src/leak_tracking/_object_tracker.dart

@@ -54,6 +54,7 @@ class ObjectTracker implements LeakProvider {
  }) {
  throwIfDisposed();
  final code = _coder(object);
+ assert(code > 0);
  if (_checkForDuplicate(code)) return;
 
  _finalizer.attach(object, code);

pkgs/leak_tracker/lib/src/leak_tracking/orchestration.dart

@@ -168,6 +168,9 @@ Future<void> forceGC({
 /// If the object is garbage collected or not retained, returns null.
 ///
 /// Does not work in web and in release mode.
+///
+/// Also does not work for objects that are not returned by getInstances.
+/// https://github.com/dart-lang/sdk/blob/3e80d29fd6fec56187d651ce22ea81f1e8732214/runtime/vm/object_graph.cc#L1803
 Future<String?> formattedRetainingPath(WeakReference ref) async {
  if (ref.target == null) return null;
  final path = await obtainRetainingPath(

pkgs/leak_tracker/lib/src/leak_tracking/retaining_path/_retaining_path.dart

@@ -9,7 +9,13 @@ import 'package:vm_service/vm_service.dart';
 
 import '_connection.dart';
 
+/// Obtains retainig path for an object.
+///
+/// Does not work for objects that have [identityHashCode] equal to 0.
+/// https://github.com/dart-lang/sdk/blob/3e80d29fd6fec56187d651ce22ea81f1e8732214/runtime/vm/object_graph.cc#L1803
 Future<RetainingPath?> obtainRetainingPath(Type type, int code) async {
+ assert(code > 0);
+
  final connection = await connect();
 
  final fp = _ObjectFingerprint(type, code);
@@ -26,7 +32,7 @@ Future<RetainingPath?> obtainRetainingPath(Type type, int code) async {
 }
 
 class _ObjectFingerprint {
- _ObjectFingerprint(this.type, this.code);
+ _ObjectFingerprint(this.type, this.code) : assert(code > 0);
 
  final Type type;
  final int code;
@@ -39,6 +45,11 @@ class _ObjectFingerprint {
  }
 }
 
+/// Finds and object in an isolate.
+///
+/// This method will NOT find objects, that have [identityHashCode] equal to 0
+/// in result of `getInstances`.
+/// https://github.com/dart-lang/sdk/blob/3e80d29fd6fec56187d651ce22ea81f1e8732214/runtime/vm/object_graph.cc#L1803
 Future<_ItemInIsolate?> _objectInIsolate(
  Connection connection,
  _ObjectFingerprint object,
@@ -58,6 +69,9 @@ Future<_ItemInIsolate?> _objectInIsolate(
  .instances ??
  <ObjRef>[];
 
+ if (instances.isEmpty) continue;
+ assert(_refIsIdentifiable(instances.first));
+
  final result = instances.firstWhereOrNull(
  (objRef) =>
  objRef is InstanceRef && objRef.identityHashCode == object.code,
@@ -73,6 +87,10 @@ Future<_ItemInIsolate?> _objectInIsolate(
  return null;
 }
 
+bool _refIsIdentifiable(ObjRef ref) {
+ return ref is InstanceRef && (ref.identityHashCode ?? 0) > 0;
+}
+
 /// Represents an item in an isolate.
 ///
 /// It can be class or object.

pkgs/leak_tracker/pubspec.yaml

@@ -1,5 +1,5 @@
 name: leak_tracker
-version: 7.0.6
+version: 7.0.7
 description: A framework for memory leak tracking for Dart and Flutter applications.
 repository: https://github.com/dart-lang/leak_tracker/tree/main/pkgs/leak_tracker