Reintroduce runtime zone to Isolate.

src/zone.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 48 matching lines @@
  public:
   explicit Zone(Isolate* isolate);
   ~Zone();
   // Allocate 'size' bytes of memory in the Zone; expands the Zone by
   // allocating new segments of memory on demand using malloc().
   inline void* New(int size);
 
   template <typename T>
   inline T* NewArray(int length);
 
+  // Deletes all objects and free all memory allocated in the Zone. Keeps one
+  // small (size <= kMaximumKeptSegmentSize) segment around if it finds one.
+  void DeleteAll();
+
+  // Deletes the last small segment kept around by DeleteAll(). You
+  // may no longer allocate in the Zone after a call to this method.
+  void DeleteKeptSegment();
+
   // Returns true if more memory has been allocated in zones than
   // the limit allows.
   inline bool excess_allocation();
 
   inline void adjust_segment_bytes_allocated(int delta);
 
   inline unsigned allocation_size() { return allocation_size_; }
 
   inline Isolate* isolate() { return isolate_; }
 
  private:
   friend class Isolate;
 
   // All pointers returned from New() have this alignment.  In addition, if the
   // object being allocated has a size that is divisible by 8 then its alignment
   // will be 8.
   static const int kAlignment = kPointerSize;
 
   // Never allocate segments smaller than this size in bytes.
   static const int kMinimumSegmentSize = 8 * KB;
 
   // Never allocate segments larger than this size in bytes.
   static const int kMaximumSegmentSize = 1 * MB;
 
+  // Never keep segments larger than this size in bytes around.
+  static const int kMaximumKeptSegmentSize = 64 * KB;
+
   // Report zone excess when allocation exceeds this limit.
   static const int kExcessLimit = 256 * MB;
 
   // The number of bytes allocated in this zone so far.
   unsigned allocation_size_;
 
   // The number of bytes allocated in segments.  Note that this number
   // includes memory allocated from the OS but not yet allocated from
   // the zone.
   int segment_bytes_allocated_;
 
   // Expand the Zone to hold at least 'size' more bytes and allocate
   // the bytes. Returns the address of the newly allocated chunk of
   // memory in the Zone. Should only be called if there isn't enough
   // room in the Zone already.
   Address NewExpand(int size);
 
   // Creates a new segment, sets it size, and pushes it to the front
   // of the segment chain. Returns the new segment.
-  Segment* NewSegment(int size);
+  INLINE(Segment* NewSegment(int size));
 
   // Deletes the given segment. Does not touch the segment chain.
-  void DeleteSegment(Segment* segment, int size);
+  INLINE(void DeleteSegment(Segment* segment, int size));
 
   // The free region in the current (front) segment is represented as
   // the half-open interval [position, limit). The 'position' variable
   // is guaranteed to be aligned as dictated by kAlignment.
   Address position_;
   Address limit_;
 
   Segment* segment_head_;
   Isolate* isolate_;
 };
@@ skipping 12 matching lines @@
   // require the operator to be visible. MSVC requires the delete
   // operator to be public.
 
   // ZoneObjects should never be deleted individually; use
   // Zone::DeleteAll() to delete all zone objects in one go.
   void operator delete(void*, size_t) { UNREACHABLE(); }
   void operator delete(void* pointer, Zone* zone) { UNREACHABLE(); }
 };
 
 
+// The ZoneScope is used to automatically call DeleteAll() on a
+// Zone when the ZoneScope is destroyed (i.e. goes out of scope)
+struct ZoneScope {
+ public:
+  explicit ZoneScope(Zone* zone) : zone_(zone) { }
+  ~ZoneScope() { zone_->DeleteAll(); }
+
+  Zone* zone() { return zone_; }
+
+ private:
+  Zone* zone_;
+};
+
+
 // The ZoneAllocationPolicy is used to specialize generic data
 // structures to allocate themselves and their elements in the Zone.
 struct ZoneAllocationPolicy {
  public:
   explicit ZoneAllocationPolicy(Zone* zone) : zone_(zone) { }
   INLINE(void* New(size_t size));
   INLINE(static void Delete(void *pointer)) { }
 
  private:
   Zone* zone_;
@@ skipping 64 matching lines @@
       : SplayTree<Config, ZoneAllocationPolicy>(ZoneAllocationPolicy(zone)) {}
   ~ZoneSplayTree();
 };
 
 
 typedef TemplateHashMapImpl<ZoneAllocationPolicy> ZoneHashMap;
 
 } }  // namespace v8::internal
 
 #endif  // V8_ZONE_H_