Bindings: Separate WorldIdConstants into WorldTypes and WorldId

third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp

Index: third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp b/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
index 3d23c73d43c297bb6ea06936628761ccf5e5eb31..1fa1a53d1d1cc1bf021859bcdd26bb75f3cda1c6 100644
--- a/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/DOMWrapperWorld.cpp
@@ -51,7 +51,7 @@ class DOMObjectHolderBase {
 
  public:
   DOMObjectHolderBase(v8::Isolate* isolate, v8::Local<v8::Value> wrapper)
-      : m_wrapper(isolate, wrapper), m_world(0) {}
+      : m_wrapper(isolate, wrapper), m_world(nullptr) {}
   virtual ~DOMObjectHolderBase() {}
 
   DOMWrapperWorld* world() const { return m_world; }
@@ -84,24 +84,28 @@ class DOMObjectHolder : public DOMObjectHolderBase {
 unsigned DOMWrapperWorld::isolatedWorldCount = 0;
 
 PassRefPtr<DOMWrapperWorld> DOMWrapperWorld::create(v8::Isolate* isolate,
-                                                    int worldId) {
-  return adoptRef(new DOMWrapperWorld(isolate, worldId));
+                                                    WorldType worldType) {
+  DCHECK_NE(WorldType::Isolated, worldType);
+  return adoptRef(
+      new DOMWrapperWorld(isolate, worldType, getWorldIdForType(worldType)));
 }
 
-DOMWrapperWorld::DOMWrapperWorld(v8::Isolate* isolate, int worldId)
-    : m_worldId(worldId),
+DOMWrapperWorld::DOMWrapperWorld(v8::Isolate* isolate,
+                                 WorldType worldType,
+                                 int worldId)
+    : m_worldType(worldType),
+      m_worldId(worldId),
       m_domDataStore(
           WTF::wrapUnique(new DOMDataStore(isolate, isMainWorld()))) {
-  if (worldId == WorkerWorldId) {
+  if (isWorkerWorld())
     workerWorld() = this;
-  }
 }
 
 DOMWrapperWorld& DOMWrapperWorld::mainWorld() {
   ASSERT(isMainThread());
   DEFINE_STATIC_REF(
       DOMWrapperWorld, cachedMainWorld,
-      (DOMWrapperWorld::create(v8::Isolate::GetCurrent(), MainWorldId)));
+      (DOMWrapperWorld::create(v8::Isolate::GetCurrent(), WorldType::Main)));
   return *cachedMainWorld;
 }
 
@@ -191,7 +195,8 @@ void DOMWrapperWorld::dispose() {
 
 #if DCHECK_IS_ON()
 static bool isIsolatedWorldId(int worldId) {
-  return MainWorldId < worldId && worldId < IsolatedWorldIdLimit;
+  return DOMWrapperWorld::MainWorldId < worldId &&
+         worldId < DOMWrapperWorld::IsolatedWorldIdLimit;
 }
 #endif
 
@@ -208,7 +213,7 @@ PassRefPtr<DOMWrapperWorld> DOMWrapperWorld::ensureIsolatedWorld(
     return world.release();
   }
 
-  world = DOMWrapperWorld::create(isolate, worldId);
+  world = adoptRef(new DOMWrapperWorld(isolate, WorldType::Isolated, worldId));
   result.storedValue->value = world.get();
   isolatedWorldCount++;
   return world.release();
@@ -315,4 +320,23 @@ void DOMWrapperWorld::weakCallbackForDOMObjectHolder(
   holderBase->world()->unregisterDOMObjectHolder(holderBase);
 }
 
+int DOMWrapperWorld::getWorldIdForType(WorldType worldType) {

[Yuki, 2017/03/08 14:07:51]

IIUC, this function is going to be used to get an identifier for a **new** world
being created, right?  This function should return a different ID for every call
(on the same thread).

If so, "get"WorldIdForType sounds weird to me because "get" implies that it
returns an existing one.  I'd prefer newWorldIdForType.

[nhiroki, 2017/03/09 03:40:28]

I'd prefer to rename this in my second patch that makes this return a different
id every time because in this patch this function always returns an existing id
for a type.

+  switch (worldType) {
+    case WorldType::Unknown:
+      return UnknownWorldId;

[Yuki, 2017/03/08 14:07:51]

I think "Unknown" is not a good name.

It seems that use cases are
  V8GCController::collectGarbage
  V8PerIsolateData::ensureScriptRegexpContext
  DataConsumerHandleTestUtil::Thread::initialize

Then, I'd like to give types for each one.
For example,
  GarbageCollector
  RegExp
  Testing  // Ideally, I'd like to deprecate this one.

Otherwise, I'd like to assign an unique ID for each at least, like
DocumentXMLTreeViewerWorldId.

[nhiroki, 2017/03/09 03:40:28]

Done.

+    case WorldType::Main:
+      return MainWorldId;
+    case WorldType::Isolated:
+      NOTREACHED();

[Yuki, 2017/03/08 14:07:51]

Could you add a comment about the reason why we don't hit this?

I've already read your reply, but I'd like to have it as a comment here.

[nhiroki, 2017/03/09 03:40:28]

Done.

+      return UnknownWorldId;
+    // Currently, WorldId for a worker/worklet is a fixed value, but this
+    // doesn't work when multiple worklets are created on a thread.
+    // TODO(nhiroki): Expand the identifier space for workers/worklets.
+    case WorldType::Worker:
+      return WorkerWorldId;
+  }
+  NOTREACHED();
+  return UnknownWorldId;
+}
+
 }  // namespace blink