Weak Cells

test/cctest/test-heap.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 4223 matching lines @@
                 "   var proto = {'name' : 'weak'};"
                 "   var obj = Object.create(proto);"
                 "   compareNilIC(obj);"
                 "   compareNilIC(obj);"
                 "   compareNilIC(obj);"
                 "   return proto;"
                 " })();");
 }
 
 
+TEST(WeakCell) {
+  CcTest::InitializeVM();
+  Isolate* isolate = CcTest::i_isolate();
+  v8::internal::Heap* heap = CcTest::heap();
+  v8::internal::Factory* factory = isolate->factory();
+
+  HandleScope outer_scope(isolate);
+  Handle<WeakCell> weak_cell;
+  {
+    HandleScope inner_scope(isolate);
+    Handle<HeapObject> value = factory->NewFixedArray(1, NOT_TENURED);
+    weak_cell = inner_scope.CloseAndEscape(factory->NewWeakCell(value));
+  }
+  CHECK(weak_cell->value()->IsFixedArray());
+  heap->CollectGarbage(NEW_SPACE);
+  CHECK(weak_cell->value()->IsFixedArray());
+  heap->CollectGarbage(NEW_SPACE);
+  CHECK(weak_cell->value()->IsFixedArray());
+  heap->CollectAllAvailableGarbage();

[Erik Corry, 2014/10/13 15:56:17]

The tests should also test that the weak cell is unchanged if there is a full GC
and the value is also reachable through normal objects.

[ulan, 2014/10/14 10:17:22]

Done.

+  CHECK(weak_cell->value()->IsUndefined());
+}
+
+
+TEST(WeakCellsWithIncrementalMarking) {
+  CcTest::InitializeVM();
+  Isolate* isolate = CcTest::i_isolate();
+  v8::internal::Heap* heap = CcTest::heap();
+  v8::internal::Factory* factory = isolate->factory();
+
+  const int N = 16;
+  HandleScope outer_scope(isolate);
+  Handle<FixedArray> survivor = factory->NewFixedArray(1, NOT_TENURED);
+  Handle<WeakCell> weak_cells[N];
+
+  for (int i = 0; i < N; i++) {
+    HandleScope inner_scope(isolate);
+    Handle<HeapObject> value =
+        i == 0 ? survivor : factory->NewFixedArray(1, NOT_TENURED);
+    Handle<WeakCell> weak_cell = factory->NewWeakCell(value);
+    CHECK(weak_cell->value()->IsFixedArray());
+    IncrementalMarking* marking = heap->incremental_marking();
+    if (marking->IsStopped()) marking->Start();
+    marking->Step(128, IncrementalMarking::NO_GC_VIA_STACK_GUARD);
+    heap->CollectGarbage(NEW_SPACE);
+    CHECK(weak_cell->value()->IsFixedArray());
+    weak_cells[i] = inner_scope.CloseAndEscape(weak_cell);
+  }
+  heap->CollectAllGarbage(Heap::kNoGCFlags);
+  CHECK_EQ(*survivor, weak_cells[0]->value());
+  for (int i = 1; i < N; i++) {
+    CHECK(weak_cells[i]->value()->IsUndefined());
+  }
+}
+
+
 #ifdef DEBUG
 TEST(AddInstructionChangesNewSpacePromotion) {
   i::FLAG_allow_natives_syntax = true;
   i::FLAG_expose_gc = true;
   i::FLAG_stress_compaction = true;
   i::FLAG_gc_interval = 1000;
   CcTest::InitializeVM();
   if (!i::FLAG_allocation_site_pretenuring) return;
   v8::HandleScope scope(CcTest::isolate());
   Isolate* isolate = CcTest::i_isolate();
@@ skipping 251 matching lines @@
 #ifdef DEBUG
 TEST(PathTracer) {
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
 
   v8::Local<v8::Value> result = CompileRun("'abc'");
   Handle<Object> o = v8::Utils::OpenHandle(*result);
   CcTest::i_isolate()->heap()->TracePathToObject(*o);
 }
 #endif  // DEBUG