Object.observe: use JSWeakMaps instead of raw ObjectHashTables in observation state

src/runtime.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 845 matching lines @@
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_MapGetSize) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSMap, holder, 0);
   Handle<ObjectHashTable> table(ObjectHashTable::cast(holder->table()));
   return Smi::FromInt(table->NumberOfElements());
 }
 
 
-RUNTIME_FUNCTION(MaybeObject*, Runtime_WeakMapInitialize) {
-  HandleScope scope(isolate);
-  ASSERT(args.length() == 1);
-  CONVERT_ARG_HANDLE_CHECKED(JSWeakMap, weakmap, 0);
+static JSWeakMap* WeakMapInitialize(Isolate* isolate,
+                                    Handle<JSWeakMap> weakmap) {
   ASSERT(weakmap->map()->inobject_properties() == 0);
   Handle<ObjectHashTable> table = isolate->factory()->NewObjectHashTable(0);
   weakmap->set_table(*table);
   weakmap->set_next(Smi::FromInt(0));
   return *weakmap;
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_WeakMapInitialize) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSWeakMap, weakmap, 0);
+  return WeakMapInitialize(isolate, weakmap);
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_WeakMapGet) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(JSWeakMap, weakmap, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, key, 1);
   Handle<ObjectHashTable> table(ObjectHashTable::cast(weakmap->table()));
   Handle<Object> lookup(table->Lookup(*key));
   return lookup->IsTheHole() ? isolate->heap()->undefined_value() : *lookup;
 }
 
@@ skipping 12509 matching lines @@
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_GetObservationState) {
   ASSERT(args.length() == 0);
   return isolate->heap()->observation_state();
 }
 
 
-RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateObjectHashTable) {
+RUNTIME_FUNCTION(MaybeObject*, Runtime_ObservationWeakMapCreate) {
+  HandleScope scope(isolate);
   ASSERT(args.length() == 0);
-  return ObjectHashTable::Allocate(0);
+  // TODO(adamk): Currently this runtime function is only called three times per
+  // isolate. If it's called more often, the map should be moved into the
+  // strong root list.
+  Handle<Map> map =
+      isolate->factory()->NewMap(JS_WEAK_MAP_TYPE, JSWeakMap::kSize);
+  Handle<JSWeakMap> weakmap =
+      Handle<JSWeakMap>::cast(isolate->factory()->NewJSObjectFromMap(map));
+  return WeakMapInitialize(isolate, weakmap);
 }
 
 
-RUNTIME_FUNCTION(MaybeObject*, Runtime_ObjectHashTableGet) {
-  NoHandleAllocation ha;
-  ASSERT(args.length() == 2);
-  CONVERT_ARG_CHECKED(ObjectHashTable, table, 0);
-  Object* key = args[1];
-  if (key->IsJSGlobalProxy()) {
-    key = key->GetPrototype();
-    if (key->IsNull()) return isolate->heap()->undefined_value();
+RUNTIME_FUNCTION(MaybeObject*, Runtime_UnwrapGlobalProxy) {
+  ASSERT(args.length() == 1);
+  Object* object = args[0];
+  if (object->IsJSGlobalProxy()) {
+    object = object->GetPrototype();
+    if (object->IsNull()) return isolate->heap()->undefined_value();
   }
-  Object* lookup = table->Lookup(key);
-  return lookup->IsTheHole() ? isolate->heap()->undefined_value() : lookup;
+  return object;
 }
 
 
-RUNTIME_FUNCTION(MaybeObject*, Runtime_ObjectHashTableSet) {
-  HandleScope scope(isolate);
-  ASSERT(args.length() == 3);
-  CONVERT_ARG_HANDLE_CHECKED(ObjectHashTable, table, 0);
-  Handle<Object> key = args.at<Object>(1);
-  if (key->IsJSGlobalProxy()) {
-    key = handle(key->GetPrototype(), isolate);
-    if (key->IsNull()) return *table;
-  }
-  Handle<Object> value = args.at<Object>(2);
-  return *PutIntoObjectHashTable(table, key, value);
-}
-
-
 // ----------------------------------------------------------------------------
 // Implementation of Runtime
 
 #define F(name, number_of_args, result_size)                             \
   { Runtime::k##name, Runtime::RUNTIME, #name,   \
     FUNCTION_ADDR(Runtime_##name), number_of_args, result_size },
 
 
 #define I(name, number_of_args, result_size)                             \
   { Runtime::kInline##name, Runtime::INLINE,     \
@@ skipping 66 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal