Add an API for enumerating persistent handles

test/cctest/test-api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5211 matching lines @@
 
   v8::Persistent<v8::Object> object_a;
 
   {
     v8::HandleScope handle_scope;
     object_a = v8::Persistent<v8::Object>::New(v8::Object::New());
   }
 
   bool object_a_disposed = false;
   object_a.MakeWeak(&object_a_disposed, &DisposeAndSetFlag);
+  CHECK(!object_a.IsIndependent());
   object_a.MarkIndependent();
+  CHECK(object_a.IsIndependent());
   HEAP->PerformScavenge();
   CHECK(object_a_disposed);
 }
 
 
 static void InvokeScavenge() {
   HEAP->PerformScavenge();
 }
 
 
@@ skipping 10927 matching lines @@
                "  try {"
                "    return readCell();"
                "  } catch(e) {"
                "    return e.toString();"
                "  }"
                "})()",
                "ReferenceError: cell is not defined");
 }
 
 
+TEST(PersistentHandleVisitor) {
+  v8::HandleScope scope;
+  LocalContext context;
+  v8::Persistent<v8::Object> object =
+      v8::Persistent<v8::Object>::New(v8::Object::New());
+  CHECK_EQ(0, object.WrapperClassId());
+  object.SetWrapperClassId(42);
+  CHECK_EQ(42, object.WrapperClassId());
+
+  class Visitor : public v8::PersistentHandleVisitor {
+   public:
+    explicit Visitor(v8::Persistent<v8::Object> object)
+      : counter_(0), object_(object) { }
+
+    virtual void VisitPersistentHandle(Persistent<Value> value,
+                                       uint16_t class_id) {
+      if (class_id == 42) {
+        CHECK(value->IsObject());
+        v8::Persistent<v8::Object> visited =
+            v8::Persistent<v8::Object>::Cast(value);
+        CHECK_EQ(42, visited.WrapperClassId());
+        CHECK_EQ(object_, visited);
+        ++counter_;
+      }
+    }
+
+    int counter_;
+    v8::Persistent<v8::Object> object_;
+  } visitor(object);
+
+  v8::V8::VisitHandlesWithClassIds(&visitor);
+  CHECK_EQ(1, visitor.counter_);
+
+  object.Dispose();
+}
+
+
 TEST(RegExp) {
   v8::HandleScope scope;
   LocalContext context;
 
   v8::Handle<v8::RegExp> re = v8::RegExp::New(v8_str("foo"), v8::RegExp::kNone);
   CHECK(re->IsRegExp());
   CHECK(re->GetSource()->Equals(v8_str("foo")));
   CHECK_EQ(v8::RegExp::kNone, re->GetFlags());
 
   re = v8::RegExp::New(v8_str("bar"),
@@ skipping 1433 matching lines @@
 
   i::Semaphore* sem_;
   volatile int sem_value_;
 };
 
 
 THREADED_TEST(SemaphoreInterruption) {
   ThreadInterruptTest().RunTest();
 }
 #endif  // WIN32