Track external allocated memory for weak persistent handles.

runtime/vm/scavenger.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SCAVENGER_H_
 #define VM_SCAVENGER_H_
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
@@ skipping 56 matching lines @@
   // Accessors to generate code for inlined allocation.
   uword* TopAddress() { return &top_; }
   uword* EndAddress() { return &end_; }
   static intptr_t top_offset() { return OFFSET_OF(Scavenger, top_); }
   static intptr_t end_offset() { return OFFSET_OF(Scavenger, end_); }
 
   intptr_t UsedInWords() const {
     return (top_ - FirstObjectStart()) >> kWordSizeLog2;
   }
   intptr_t CapacityInWords() const { return space_->size() >> kWordSizeLog2; }
+  intptr_t ExternalAllocatedInWords() const {
+    return external_allocation_size_ >> kWordSizeLog2;
+  }
 
   void VisitObjects(ObjectVisitor* visitor) const;
   void VisitObjectPointers(ObjectPointerVisitor* visitor) const;
 
   void StartEndAddress(uword* start, uword* end) const {
     *start = to_->start();
     *end = to_->end();
   }
 
   // Returns true if the last scavenge had a promotion failure.
@@ skipping 14 matching lines @@
   void IncrementCollections() {
     collections_++;
   }
 
   intptr_t collections() const {
     return collections_;
   }
 
   void PrintToJSONObject(JSONObject* object);
 
+  void AllocateExternal(intptr_t size);
+  void FreeExternal(intptr_t size);
+
  private:
   // Ids for time and data records in Heap::GCStats.
   enum {
     // Time
     kVisitIsolateRoots = 0,
     kIterateStoreBuffers = 1,
     kProcessToSpace = 2,
     kIterateWeaks = 3,
     // Data
     kStoreBufferEntries = 0,
@@ skipping 21 matching lines @@
                 ScavengerVisitor* visitor,
                 bool invoke_api_callbacks);
 
   bool IsUnreachable(RawObject** p);
 
   // During a scavenge we need to remember the promoted objects.
   // This is implemented as a stack of objects at the end of the to space. As
   // object sizes are always greater than sizeof(uword) and promoted objects do
   // not consume space in the to space they leave enough room for this stack.
   void PushToPromotedStack(uword addr) {
+    ASSERT(scavenging_);
+    ASSERT(external_allocation_size_ == 0);
     end_ -= sizeof(addr);
     ASSERT(end_ > top_);
     *reinterpret_cast<uword*>(end_) = addr;
   }
   uword PopFromPromotedStack() {
+    ASSERT(scavenging_);
+    ASSERT(external_allocation_size_ == 0);
     uword result = *reinterpret_cast<uword*>(end_);
     end_ += sizeof(result);
     ASSERT(end_ <= to_->end());
     return result;
   }
   bool PromotedStackHasMore() const {
+    ASSERT(scavenging_);
+    ASSERT(external_allocation_size_ == 0);
     return end_ < to_->end();
   }
 
   void ProcessWeakTables();
 
   VirtualMemory* space_;
   MemoryRegion* to_;
   MemoryRegion* from_;
 
   Heap* heap_;
@@ skipping 14 matching lines @@
   uword object_alignment_;
 
   // Keep track whether a scavenge is currently running.
   bool scavenging_;
   // Keep track whether the scavenge had a promotion failure.
   bool had_promotion_failure_;
 
   int64_t gc_time_micros_;
   intptr_t collections_;
 
+  // The total size of external data associated with objects in this scavenger.
+  // External allocations decrease end_. If promoted stack is in use, this is 0.
+  intptr_t external_allocation_size_;
+
   friend class ScavengerVisitor;
   friend class ScavengerWeakVisitor;
 
   DISALLOW_COPY_AND_ASSIGN(Scavenger);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCAVENGER_H_