[heap] Add concurrency-safe refilling to compaction spaces

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 "src/base/bits.h"
 #include "src/heap/spaces.h"
 
@@ skipping 439 matching lines @@
   // to a value larger than 0, then sweeping returns after a block of at least
   // required_freed_bytes was freed. If required_freed_bytes was set to zero
   // then the whole given space is swept. It returns the size of the maximum
   // continuous freed memory chunk.
   int SweepInParallel(PagedSpace* space, int required_freed_bytes);
 
   // Sweeps a given page concurrently to the sweeper threads. It returns the
   // size of the maximum continuous freed memory chunk.
   int SweepInParallel(Page* page, PagedSpace* space);
 
+  // Ensures that sweeping is finished.
+  //
+  // Note: Can only be called safely from main thread.
   void EnsureSweepingCompleted();
 
   void SweepOrWaitUntilSweepingCompleted(Page* page);
 
+  // Help out in sweeping the corresponding space and refill memory that has
+  // been regained.
+  //
+  // Note: Thread-safe.
+  void SweepAndRefill(CompactionSpace* space);
+
   // If sweeper threads are not active this method will return true. If
   // this is a latency issue we should be smarter here. Otherwise, it will
   // return true if the sweeper threads are done processing the pages.
   bool IsSweepingCompleted();
 
   // Checks if sweeping is in progress right now on any space.
   bool sweeping_in_progress() { return sweeping_in_progress_; }
 
   void set_evacuation(bool evacuation) { evacuation_ = evacuation; }
 
@@ skipping 385 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_