[wasm] Managed<T> ensures T's lifetime does not leak past Isolate's

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 38a26be1e29a70450d6d08460fbe0e7473b25244..d25c8a20200ac0d57df2a38105d56cfe50d91709 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -2030,6 +2030,47 @@ Isolate::ThreadDataTable::~ThreadDataTable() {
   // DCHECK_NULL(list_);
 }
 
+void Isolate::ReleaseManagedObjects() {
+  Isolate::ManagedObjectFinalizer* current =
+      managed_object_finalizers_list_.next_;
+  while (current != nullptr) {
+    Isolate::ManagedObjectFinalizer* next = current->next_;
+    current->Dispose();
+    delete current;
+    current = next;
+  }
+}
+
+Isolate::ManagedObjectFinalizer* Isolate::RegisterForReleaseAtTeardown(
+    void* value, Isolate::ManagedObjectFinalizer::Deleter deleter) {
+  DCHECK_NOT_NULL(value);
+  DCHECK_NOT_NULL(deleter);
+
+  Isolate::ManagedObjectFinalizer* ret = new Isolate::ManagedObjectFinalizer();
+  ret->value_ = value;
+  ret->deleter_ = deleter;
+  // Insert at head. We keep the head alive for the lifetime of the Isolate
+  // because otherwise we can't reset the head, should we delete it before
+  // the isolate expires
+  Isolate::ManagedObjectFinalizer* next = managed_object_finalizers_list_.next_;
+  managed_object_finalizers_list_.next_ = ret;
+  ret->prev_ = &managed_object_finalizers_list_;
+  ret->next_ = next;
+  if (next != nullptr) next->prev_ = ret;
+  return ret;
+}
+
+void Isolate::UnregisterFromReleaseAtTeardown(
+    Isolate::ManagedObjectFinalizer** finalizer_ptr) {
+  DCHECK_NOT_NULL(finalizer_ptr);
+  Isolate::ManagedObjectFinalizer* finalizer = *finalizer_ptr;
+  DCHECK_NOT_NULL(finalizer->prev_);
+
+  finalizer->prev_->next_ = finalizer->next_;
+  if (finalizer->next_ != nullptr) finalizer->next_->prev_ = finalizer->prev_;
+  delete finalizer;
+  *finalizer_ptr = nullptr;
+}
 
 Isolate::PerIsolateThreadData::~PerIsolateThreadData() {
 #if defined(USE_SIMULATOR)
@@ -2399,6 +2440,7 @@ void Isolate::Deinit() {
   root_index_map_ = NULL;
 
   ClearSerializerData();
+  ReleaseManagedObjects();
 }