Reapply "Background finalization."

runtime/vm/dart_api_state.cc

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/dart_api_state.h"
+
+#include "platform/assert.h"
+#include "platform/utils.h"
+#include "vm/heap.h"
+#include "vm/isolate.h"
+#include "vm/lockers.h"
+#include "vm/thread.h"
+#include "vm/timeline.h"
+
+namespace dart {
+
+BackgroundFinalizer::BackgroundFinalizer(Isolate* isolate,
+                                         FinalizationQueue* queue) :
+    isolate_(isolate),
+    queue_(queue) {
+  MonitorLocker ml(isolate->heap()->finalization_tasks_lock());
+  isolate->heap()->set_finalization_tasks(
+      isolate->heap()->finalization_tasks() + 1);
+  ml.Notify();
+}
+
+
+void BackgroundFinalizer::Run() {
+  {

[siva, 2016/06/22 22:55:31]

You can avoid the issues with entering the isolate by transitioning to Native
before the callback in FinalizablePersistentHandle::Finalize
actually that is a bug currently.

[rmacnak, 2016/06/22 23:13:48]

Done.

+    TIMELINE_FUNCTION_GC_DURATION(Thread::Current(),
+                                  "BackgroundFinalization");
+
+    for (intptr_t i = 0; i < queue_->length(); i++) {
+      FinalizablePersistentHandle* handle = (*queue_)[i];
+      FinalizablePersistentHandle::Finalize(isolate_, handle);
+    }
+    delete queue_;
+  }
+
+  {
+    Heap* heap = isolate_->heap();
+    MonitorLocker ml(heap->finalization_tasks_lock());
+    heap->set_finalization_tasks(heap->finalization_tasks() - 1);
+    ml.Notify();
+  }
+}
+
+}  // namespace dart