Modify the Weak Reference Set creation API to make it easier to create

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 <vector>
 
@@ skipping 356 matching lines @@
       ASSERT(reference_set != NULL);
       bool is_unreachable = true;
       // Test each key object for reachability.  If a key object is
       // reachable, all value objects should be marked.
       for (intptr_t k = 0; k < reference_set->num_keys(); ++k) {
         if (!IsUnreachable(*reference_set->get_key(k))) {
           for (intptr_t v = 0; v < reference_set->num_values(); ++v) {
             visitor->VisitPointer(reference_set->get_value(v));
           }
           is_unreachable = false;
-          delete reference_set;
           break;

[Ivan Posva, 2014/04/17 23:47:44]

Please add a comment that this break is breaking out of the loop iterating over
the weak reference values in the set and not out of the overall handling.

[siva, 2014/04/21 18:04:14]

Done.

         }
       }
       // If all key objects are unreachable put the reference on a
       // delay queue.  This reference will be revisited if another
       // reference is marked.
       if (is_unreachable) {
         state->DelayWeakReferenceSet(reference_set);
       }
     }
     if (!visitor->marking_stack()->IsEmpty()) {
       DrainMarkingStack(isolate, visitor);
     } else {
       // Break out of the loop if there has been no forward process.
       break;
     }
   }
-  // Deallocate any unmarked references on the delay queue.
-  if (state->delayed_weak_reference_sets() != NULL) {
-    WeakReferenceSet* queue = state->delayed_weak_reference_sets();
-    state->set_delayed_weak_reference_sets(NULL);
-    while (queue != NULL) {
-      delete WeakReferenceSet::Pop(&queue);
-    }
-  }
+  // All weak reference sets are zone allocated and unmarked references on
+  // the delay queue will be freed when the zone is released in the epilog
+  // callback.
 }
 
 
 void GCMarker::DrainMarkingStack(Isolate* isolate,
                                  MarkingVisitor* visitor) {
   while (!visitor->marking_stack()->IsEmpty()) {
     RawObject* raw_obj = visitor->marking_stack()->Pop();
     visitor->VisitingOldObject(raw_obj);
     if (raw_obj->GetClassId() != kWeakPropertyCid) {
       raw_obj->VisitPointers(visitor);
@@ skipping 84 matching lines @@
   MarkingWeakVisitor mark_weak;
   IterateWeakRoots(isolate, &mark_weak, invoke_api_callbacks);
   mark.Finalize();
   ProcessWeakTables(page_space);
   ProcessObjectIdTable(isolate);
 
   Epilogue(isolate, invoke_api_callbacks);
 }
 
 }  // namespace dart