[heap] Integrate embedder heap tracer into incremental marking

src/heap/mark-compact.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include <deque>
 
 #include "src/base/bits.h"
@@ skipping 472 matching lines @@
   // when mark bits are still intact.
   bool IsSlotInBlackObject(MemoryChunk* p, Address slot);
   HeapObject* FindBlackObjectBySlotSlow(Address slot);
 
   // Removes all the slots in the slot buffers that are within the given
   // address range.
   void RemoveObjectSlots(Address start_slot, Address end_slot);
 
   Sweeper& sweeper() { return sweeper_; }
 
+  // ===========================================================================
+  // Embedder heap tracer support. =============================================
+  // ===========================================================================
+
+  void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
+  EmbedderHeapTracer* embedder_heap_tracer() { return embedder_heap_tracer_; }
+  bool UsingEmbedderHeapTracer() { return embedder_heap_tracer(); }
+
+  // In order to avoid running out of memory we force tracing wrappers if there
+  // are too many of them.
+  bool RequiresImmediateWrapperProcessing();
+
   void RegisterWrappersWithEmbedderHeapTracer();
 
-  void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
+  void TracePossibleWrapper(JSObject* js_object);
 
-  EmbedderHeapTracer* embedder_heap_tracer() { return embedder_heap_tracer_; }
-
-  bool UsingEmbedderHeapTracer() { return embedder_heap_tracer(); }
-
-  void TracePossibleWrapper(JSObject* js_object);
+  size_t wrappers_to_trace() { return wrappers_to_trace_.size(); }
 
  private:
   class EvacuateNewSpacePageVisitor;
   class EvacuateNewSpaceVisitor;
   class EvacuateOldSpaceVisitor;
   class EvacuateRecordOnlyVisitor;
   class EvacuateVisitorBase;
   class HeapObjectVisitor;
   class ObjectStatsVisitor;
 
@@ skipping 255 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_