Lazy peer API.

runtime/vm/gc_marker.cc

 // Copyright (c) 2011, 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/gc_marker.h"
 
 #include <map>
 #include <utility>
 
 #include "vm/allocation.h"
@@ skipping 360 matching lines @@
   if (!raw_key->IsMarked()) {
     // Key is white.  Delay the weak property.
     visitor->DelayWeakProperty(raw_weak);
   } else {
     // Key is gray or black.  Make the weak property black.
     raw_weak->VisitPointers(visitor);
   }
 }
 
 
+void GCMarker::ProcessPeerReferents() {
+  std::map<RawObject*, void*>::iterator it = peer_->begin();
+  while (it != peer_->end()) {
+    RawObject* raw_obj = it->first;
+    ASSERT(raw_obj->IsHeapObject());
+    if (raw_obj->IsMarked()) {
+      // The object has survived.  Do nothing.
+      ++it;
+    } else {
+      // The object has become garbage.  Remove its record.
+      peer_->erase(it++);
+    }
+  }
+}
+
+
 void GCMarker::MarkObjects(Isolate* isolate,
                            PageSpace* page_space,
                            bool invoke_api_callbacks) {
   MarkingStack marking_stack;
   Prologue(isolate, invoke_api_callbacks);
   MarkingVisitor mark(isolate, heap_, page_space, &marking_stack);
   IterateRoots(isolate, &mark, !invoke_api_callbacks);
   DrainMarkingStack(isolate, &mark);
   IterateWeakReferences(isolate, &mark);
   MarkingWeakVisitor mark_weak;
   IterateWeakRoots(isolate, &mark_weak, invoke_api_callbacks);
   mark.Finalize();
+  ProcessPeerReferents();
   Epilogue(isolate, invoke_api_callbacks);
 }
 
 }  // namespace dart