Add a second kind of HandleScope that ties the lifetime of Handles created in its scope to the life…

src/handles.h

 // Copyright 2011 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 77 matching lines @@
 
   // Closes the given scope, but lets this handle escape. See
   // implementation in api.h.
   inline Handle<T> EscapeFrom(v8::HandleScope* scope);
 
  private:
   T** location_;
 };
 
 
+class HandleScopeImplementer;
+
+
 // A stack-allocated class that governs a number of local handles.
 // After a handle scope has been created, all local handles will be
 // allocated within that handle scope until either the handle scope is
 // deleted or another handle scope is created.  If there is already a
 // handle scope and a new one is created, all allocations will take
 // place in the new handle scope until it is deleted.  After that,
 // new handles will again be allocated in the original handle scope.
 //
 // After the handle scope of a local handle has been deleted the
 // garbage collector will no longer track the object stored in the
@@ skipping 42 matching lines @@
   Object** prev_next_;
   Object** prev_limit_;
 
   // Extend the handle scope making room for more handles.
   static internal::Object** Extend();
 
   // Zaps the handles in the half-open interval [start, end).
   static void ZapRange(internal::Object** start, internal::Object** end);
 
   friend class v8::HandleScope;
+  friend class v8::internal::HandleScopeImplementer;
   friend class v8::ImplementationUtilities;
 };
 
 
+class DeferredHandles;
+
+
+class DeferredHandleScope {
+ public:
+  explicit DeferredHandleScope(Isolate* isolate);
+  // The DeferredHandles object returned stores the Handles created
+  // since the creation of this DeferredHandleScope.  The Handles are
+  // alive till as long as the DeferredHandles object is alive.

[Erik Corry, 2012/06/27 10:28:15]

till as long as -> as long as

[sanjoy, 2012/06/27 11:17:09]

Fixed.

+  DeferredHandles* Detach();
+  ~DeferredHandleScope();
+
+ private:
+  Object** prev_limit_;
+  Object** prev_next_;
+  HandleScopeImplementer* impl_;
+
+#ifdef DEBUG
+  bool handles_detached_;
+  int prev_level_;
+#endif
+
+  friend class HandleScopeImplementer;
+};
+
+
+class CompilationInfo;

[Erik Corry, 2012/06/27 10:28:15]

This declaration and the CompilationHandleScope are uses of handles and not part
of the handles interface, so they should go somewhere else, like perhaps
hydrogen.h

[sanjoy, 2012/06/27 11:17:09]

Moved to compiler.h.

+
+
+// A wrapper around a CompilationInfo that Detaches the Handles from

[Erik Corry, 2012/06/27 10:28:15]

Detaches -> detaches

[sanjoy, 2012/06/27 11:17:09]

Fixed.

+// the underlying DeferredHandleScope and stores them in info_ on
+// destruction.
+class CompilationHandleScope BASE_EMBEDDED {
+ public:
+  explicit CompilationHandleScope(CompilationInfo* info);
+  ~CompilationHandleScope();
+
+ private:
+  DeferredHandleScope deferred_;
+  CompilationInfo* info_;
+};
+
+
 // ----------------------------------------------------------------------------
 // Handle operations.
 // They might invoke garbage collection. The result is an handle to
 // an object of expected type, or the handle is an error if running out
 // of space or encountering an internal error.
 
 // Flattens a string.
 void FlattenString(Handle<String> str);
 
 // Flattens a string and returns the underlying external or sequential
@@ skipping 119 matching lines @@
   inline NoHandleAllocation();
   inline ~NoHandleAllocation();
  private:
   int level_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_