- Add and enable concurrent sweeper.

runtime/vm/store_buffer.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_STORE_BUFFER_H_
 #define VM_STORE_BUFFER_H_
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 
@@ skipping 34 matching lines @@
 
   friend class StoreBuffer;
 
   DISALLOW_COPY_AND_ASSIGN(StoreBufferBlock);
 };
 
 
 class StoreBuffer {
  public:
   StoreBuffer() : blocks_(new StoreBufferBlock(NULL)), full_count_(0) {}
+  explicit StoreBuffer(bool shallow_copy) : blocks_(NULL), full_count_(0) {
+    // The value shallow_copy is only used to select this non-allocating
+    // constructor. It is always expected to be true.
+    ASSERT(shallow_copy);
+  }
   ~StoreBuffer();
 
   intptr_t Count() const {
     return blocks_->Count() + (full_count_ * StoreBufferBlock::kSize);
   }
 
   void Reset();
 
   void AddObject(RawObject* obj) {
     StoreBufferBlock* block = blocks_;
@@ skipping 34 matching lines @@
 
   StoreBufferBlock* blocks_;
   intptr_t full_count_;
 
   DISALLOW_COPY_AND_ASSIGN(StoreBuffer);
 };
 
 }  // namespace dart
 
 #endif  // VM_STORE_BUFFER_H_