[api] Remove EmbedderReachableReferenceReporter

API was highly experimental. Embedders should use V8::RegisterExternalReference instead.

BUG=chromium:468240
R=jochen@chromium.org

Review-Url: https://codereview.chromium.org/2474163002
Cr-Commit-Position: refs/heads/master@{#40769}

include/v8-util.h

@@ -206,19 +206,14 @@ class PersistentValueMapBase {
   }
 
   /**
-   * Deprecated. Call V8::RegisterExternallyReferencedObject with the map value
-   * for given key.
-   * TODO(hlopko) Remove once migration to reporter is finished.
+   * Call V8::RegisterExternallyReferencedObject with the map value for given
+   * key.
    */
-  void RegisterExternallyReferencedObject(K& key) {}
-
-  /**
-   * Use EmbedderReachableReferenceReporter with the map value for given key.
-   */
-  void RegisterExternallyReferencedObject(
-      EmbedderReachableReferenceReporter* reporter, K& key) {
+  void RegisterExternallyReferencedObject(K& key) {
     DCHECK(Contains(key));
-    reporter->ReportExternalReference(FromVal(Traits::Get(&impl_, key)));
+    V8::RegisterExternallyReferencedObject(
+        reinterpret_cast<internal::Object**>(FromVal(Traits::Get(&impl_, key))),
+        reinterpret_cast<internal::Isolate*>(GetIsolate()));
   }
 
   /**

include/v8.h

@@ -462,16 +462,6 @@ class WeakCallbackInfo {
 // possible to request a second pass callback.
 enum class WeakCallbackType { kParameter, kInternalFields, kFinalizer };
 
-/**
- * A reporter class that embedder will use to report reachable references found
- * by EmbedderHeapTracer.
- */
-class V8_EXPORT EmbedderReachableReferenceReporter {
- public:
-  virtual void ReportExternalReference(Value* object) = 0;
-  virtual ~EmbedderReachableReferenceReporter() = default;
-};
-
 /**
  * An object reference that is independent of any handle scope.  Where
  * a Local handle only lives as long as the HandleScope in which it was
@@ -568,19 +558,12 @@ template <class T> class PersistentBase {
   // TODO(dcarney): remove this.
   V8_INLINE void ClearWeak() { ClearWeak<void>(); }
 
-  /**
-   * Deprecated.
-   * TODO(hlopko): remove once migration to reporter is finished.
-   */
-  V8_INLINE void RegisterExternalReference(Isolate* isolate) const {}
-
   /**
    * Allows the embedder to tell the v8 garbage collector that a certain object
    * is alive. Only allowed when the embedder is asked to trace its heap by
    * EmbedderHeapTracer.
    */
-  V8_INLINE void RegisterExternalReference(
-      EmbedderReachableReferenceReporter* reporter) const;
+  V8_INLINE void RegisterExternalReference(Isolate* isolate) const;
 
   /**
    * Marks the reference to this object independent. Garbage collector is free
@@ -6179,11 +6162,11 @@ class V8_EXPORT PersistentHandleVisitor {  // NOLINT
 enum class MemoryPressureLevel { kNone, kModerate, kCritical };
 
 /**
- * Interface for tracing through the embedder heap. During the v8 garbage
+ * Interface for tracing through the embedder heap. During a v8 garbage
  * collection, v8 collects hidden fields of all potential wrappers, and at the
  * end of its marking phase iterates the collection and asks the embedder to
- * trace through its heap and use reporter to report each js object reachable
- * from any of the given wrappers.
+ * trace through its heap and use reporter to report each JavaScript object
+ * reachable from any of the given wrappers.
  *
  * Before the first call to the TraceWrappersFrom function TracePrologue will be
  * called. When the garbage collection cycle is finished, TraceEpilogue will be
@@ -6201,30 +6184,26 @@ class V8_EXPORT EmbedderHeapTracer {
   };
 
   /**
-   * V8 will call this method with internal fields of found wrappers. The
-   * embedder is expected to store them in its marking deque and trace
-   * reachable wrappers from them when called through |AdvanceTracing|.
+   * Called by v8 to register internal fields of found wrappers.
+   *
+   * The embedder is expected to store them somewhere and trace reachable
+   * wrappers from them when called through |AdvanceTracing|.
    */
   virtual void RegisterV8References(
       const std::vector<std::pair<void*, void*> >& internal_fields) = 0;
 
   /**
-   * Deprecated.
-   * TODO(hlopko) Remove once the migration to reporter is finished.
-   */
-  virtual void TracePrologue() {}
-
-  /**
-   * V8 will call this method at the beginning of a GC cycle. Embedder is
-   * expected to use EmbedderReachableReferenceReporter for reporting all
-   * reachable v8 objects.
+   * Called at the beginning of a GC cycle.
    */
-  virtual void TracePrologue(EmbedderReachableReferenceReporter* reporter) {}
+  virtual void TracePrologue() = 0;
 
   /**
-   * Embedder is expected to trace its heap starting from wrappers reported by
-   * RegisterV8References method, and use reporter for all reachable wrappers.
-   * Embedder is expected to stop tracing by the given deadline.
+   * Called to to make a tracing step in the embedder.
+   *
+   * The embedder is expected to trace its heap starting from wrappers reported
+   * by RegisterV8References method, and report back all reachable wrappers.
+   * Furthermore, the embedder is expected to stop tracing by the given
+   * deadline.
    *
    * Returns true if there is still work to do.
    */
@@ -6232,22 +6211,25 @@ class V8_EXPORT EmbedderHeapTracer {
                               AdvanceTracingActions actions) = 0;
 
   /**
-   * V8 will call this method at the end of a GC cycle.
+   * Called at the end of a GC cycle.
    *
    * Note that allocation is *not* allowed within |TraceEpilogue|.
    */
   virtual void TraceEpilogue() = 0;
 
   /**
-   * Let embedder know v8 entered final marking pause (no more incremental steps
-   * will follow).
+   * Called upon entering the final marking pause. No more incremental marking
+   * steps will follow this call.
    */
-  virtual void EnterFinalPause() {}
+  virtual void EnterFinalPause() = 0;
 
   /**
-   * Throw away all intermediate data and reset to the initial state.
+   * Called when tracing is aborted.
+   *
+   * The embedder is expected to throw away all intermediate data and reset to
+   * the initial state.
    */
-  virtual void AbortTracing() {}
+  virtual void AbortTracing() = 0;
 
   /**
    * Returns the number of wrappers that are still to be traced by the embedder.
@@ -7560,6 +7542,9 @@ class V8_EXPORT V8 {
                          int* index);
   static Local<Value> GetEternal(Isolate* isolate, int index);
 
+  static void RegisterExternallyReferencedObject(internal::Object** object,
+                                                 internal::Isolate* isolate);
+
   template <class K, class V, class T>
   friend class PersistentValueMapBase;
 
@@ -8621,10 +8606,11 @@ P* PersistentBase<T>::ClearWeak() {
 }
 
 template <class T>
-void PersistentBase<T>::RegisterExternalReference(
-    EmbedderReachableReferenceReporter* reporter) const {
+void PersistentBase<T>::RegisterExternalReference(Isolate* isolate) const {
   if (IsEmpty()) return;
-  reporter->ReportExternalReference(this->val_);
+  V8::RegisterExternallyReferencedObject(
+      reinterpret_cast<internal::Object**>(this->val_),
+      reinterpret_cast<internal::Isolate*>(isolate));
 }
 
 template <class T>

src/api.cc

@@ -812,6 +812,11 @@ i::Object** V8::CopyPersistent(i::Object** obj) {
   return result.location();
 }
 
+void V8::RegisterExternallyReferencedObject(i::Object** object,
+                                            i::Isolate* isolate) {
+  isolate->heap()->RegisterExternallyReferencedObject(object);
+}
+
 void V8::MakeWeak(i::Object** location, void* parameter,
                   int internal_field_index1, int internal_field_index2,
                   WeakCallbackInfo<void>::Callback weak_callback) {

src/heap/heap.cc

@@ -156,7 +156,6 @@ Heap::Heap()
       strong_roots_list_(NULL),
       heap_iterator_depth_(0),
       embedder_heap_tracer_(nullptr),
-      embedder_reference_reporter_(new TracePossibleWrapperReporter(this)),
       force_oom_(false),
       delay_sweeper_tasks_for_testing_(false) {
 // Allow build-time customization of the max semispace size. Building
@@ -5708,9 +5707,6 @@ void Heap::TearDown() {
 
   delete memory_allocator_;
   memory_allocator_ = nullptr;
-
-  delete embedder_reference_reporter_;
-  embedder_reference_reporter_ = nullptr;
 }
 
 

src/heap/heap.h

@@ -1199,10 +1199,6 @@ class Heap {
 
   EmbedderHeapTracer* embedder_heap_tracer() { return embedder_heap_tracer_; }
 
-  EmbedderReachableReferenceReporter* embedder_reachable_reference_reporter() {
-    return embedder_reference_reporter_;
-  }
-
   size_t wrappers_to_trace() { return wrappers_to_trace_.size(); }
 
   // ===========================================================================
@@ -2309,7 +2305,6 @@ class Heap {
   int heap_iterator_depth_;
 
   EmbedderHeapTracer* embedder_heap_tracer_;
-  EmbedderReachableReferenceReporter* embedder_reference_reporter_;
   std::vector<std::pair<void*, void*>> wrappers_to_trace_;
 
   // Used for testing purposes.
@@ -2633,18 +2628,6 @@ class AllocationObserver {
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
-class TracePossibleWrapperReporter : public EmbedderReachableReferenceReporter {
- public:
-  explicit TracePossibleWrapperReporter(Heap* heap) : heap_(heap) {}
-  void ReportExternalReference(Value* object) override {
-    heap_->RegisterExternallyReferencedObject(
-        reinterpret_cast<Object**>(object));
-  }
-
- private:
-  Heap* heap_;
-};
-
 }  // namespace internal
 }  // namespace v8
 

src/heap/incremental-marking.cc

@@ -528,8 +528,7 @@ void IncrementalMarking::StartMarking() {
   if (heap_->UsingEmbedderHeapTracer()) {
     TRACE_GC(heap()->tracer(),
              GCTracer::Scope::MC_INCREMENTAL_WRAPPER_PROLOGUE);
-    heap_->embedder_heap_tracer()->TracePrologue(
-        heap_->embedder_reachable_reference_reporter());
+    heap_->embedder_heap_tracer()->TracePrologue();
   }
 
   RecordWriteStub::Mode mode = is_compacting_

src/heap/mark-compact.cc

@@ -811,8 +811,7 @@ void MarkCompactCollector::Prepare() {
   if (!was_marked_incrementally_) {
     if (heap_->UsingEmbedderHeapTracer()) {
       TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WRAPPER_PROLOGUE);
-      heap_->embedder_heap_tracer()->TracePrologue(
-          heap_->embedder_reachable_reference_reporter());
+      heap_->embedder_heap_tracer()->TracePrologue();
     }
   }