[heap] Scalable slots buffer for parallel compaction.

src/heap/slots-buffer.h

 // Copyright 2015 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_SLOTS_BUFFER_H_
 #define V8_HEAP_SLOTS_BUFFER_H_
 
 #include "src/objects.h"
 
 namespace v8 {
@@ skipping 104 matching lines @@
   inline bool IsFull() { return idx_ == kNumberOfElements; }
 
   inline bool HasSpaceForTypedSlot() { return idx_ < kNumberOfElements - 1; }
 
   enum AdditionMode { FAIL_ON_OVERFLOW, IGNORE_OVERFLOW };
 
   static bool ChainLengthThresholdReached(SlotsBuffer* buffer) {
     return buffer != NULL && buffer->chain_length_ >= kChainLengthThreshold;
   }
 
-  INLINE(static bool AddToSynchronized(SlotsBufferAllocator* allocator,
-                                       SlotsBuffer** buffer_address,
-                                       base::Mutex* buffer_mutex,
-                                       ObjectSlot slot, AdditionMode mode)) {
-    base::LockGuard<base::Mutex> lock_guard(buffer_mutex);
-    return AddTo(allocator, buffer_address, slot, mode);
-  }
-
   INLINE(static bool AddTo(SlotsBufferAllocator* allocator,
                            SlotsBuffer** buffer_address, ObjectSlot slot,
                            AdditionMode mode)) {
     SlotsBuffer* buffer = *buffer_address;
     if (buffer == NULL || buffer->IsFull()) {
       if (mode == FAIL_ON_OVERFLOW && ChainLengthThresholdReached(buffer)) {
         allocator->DeallocateChain(buffer_address);
         return false;
       }
       buffer = allocator->AllocateBuffer(buffer);
       *buffer_address = buffer;
     }
     buffer->Add(slot);
     return true;
   }
 
   static bool IsTypedSlot(ObjectSlot slot);
 
-  static bool AddToSynchronized(SlotsBufferAllocator* allocator,
-                                SlotsBuffer** buffer_address,
-                                base::Mutex* buffer_mutex, SlotType type,
-                                Address addr, AdditionMode mode);
-
   static bool AddTo(SlotsBufferAllocator* allocator,
                     SlotsBuffer** buffer_address, SlotType type, Address addr,
                     AdditionMode mode);
 
   // Eliminates all stale entries from the slots buffer, i.e., slots that
   // are not part of live objects anymore. This method must be called after
   // marking, when the whole transitive closure is known and must be called
   // before sweeping when mark bits are still intact.
   static void RemoveInvalidSlots(Heap* heap, SlotsBuffer* buffer);
 
@@ skipping 13 matching lines @@
   intptr_t chain_length_;
   SlotsBuffer* next_;
   ObjectSlot slots_[kNumberOfElements];
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SLOTS_BUFFER_H_