[heap] Synchronize concurrent chunk map modifications.

src/heap/spaces.h

 // Copyright 2011 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_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include <list>
 #include <memory>
 #include <unordered_set>
@@ skipping 2802 matching lines @@
 
   // Approximate amount of physical memory committed for this space.
   size_t CommittedPhysicalMemory() override;
 
   int PageCount() { return page_count_; }
 
   // Finds an object for a given address, returns a Smi if it is not found.
   // The function iterates through all objects in this space, may be slow.
   Object* FindObject(Address a);
 
+  // Takes the chunk_map_mutex_ and calls FindPage after that.
+  LargePage* FindPageThreadSafe(Address a);
+
   // Finds a large object page containing the given address, returns NULL
   // if such a page doesn't exist.
   LargePage* FindPage(Address a);
 
   // Clears the marking state of live objects.
   void ClearMarkingStateOfLiveObjects();
 
   // Frees unmarked objects.
   void FreeUnmarkedObjects();
 
@@ skipping 30 matching lines @@
   void Print() override;
   void ReportStatistics();
 #endif
 
  private:
   // The head of the linked list of large object chunks.
   LargePage* first_page_;
   size_t size_;            // allocated bytes
   int page_count_;         // number of chunks
   size_t objects_size_;    // size of objects
+  // The chunk_map_mutex_ has to be used when the chunk map is accessed
+  // concurrently.
+  base::Mutex chunk_map_mutex_;
   // Map MemoryChunk::kAlignment-aligned chunks to large pages covering them
   base::HashMap chunk_map_;
 
   friend class LargeObjectIterator;
 };
 
 
 class LargeObjectIterator : public ObjectIterator {
  public:
   explicit LargeObjectIterator(LargeObjectSpace* space);
@@ skipping 26 matching lines @@
   PageIterator old_iterator_;
   PageIterator code_iterator_;
   PageIterator map_iterator_;
   LargePageIterator lo_iterator_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_