Externalization API for ArrayBuffer

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 37bd427df205ee77771445f5448c85612b8692f5..dc80602da22ea1c37fea40b18c453a4ca07d3fb6 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -2325,6 +2325,37 @@ class V8EXPORT Function : public Object {
   static void CheckCast(Value* obj);
 };
 
+/**
+ * The contents of an |ArrayBuffer|. Externalization of |ArrayBuffer|
+ * populates an instance of this class with a pointer to data and byte length.
+ *
+ * |ArrayBufferContents| is the owner of its data. When an instance of
+ * this class is destructed, the |Data| is freed.
+ *
+ * This API is experimental and may change significantly.
+ */
+class V8EXPORT ArrayBufferContents {
+ public:
+  void* Data() const { return data_; }
+  size_t ByteLength() const { return byte_length_; }
+
+  ArrayBufferContents() : data_(NULL), byte_length_(0) {}

[Sven Panne, 2013/05/23 07:57:01]

Nit: We usually put the constructor/destructor at the beginning of the
corresponding public/protected/private section.

[Dmitry Lomov (no reviews), 2013/05/23 08:42:15]

Done.

+  ~ArrayBufferContents();
+
+ private:
+  ArrayBufferContents(void* data, size_t byte_length)
+    : data_(data), byte_length_(byte_length)
+  { }

[Sven Panne, 2013/05/23 07:57:01]

Nit: Put this at the end of the initializer list.

[Dmitry Lomov (no reviews), 2013/05/23 08:42:15]

Done.

+
+  void* data_;
+  size_t byte_length_;
+
+  friend class ArrayBuffer;
+};
+
+#ifndef V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT
+#define V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT 2
+#endif
 
 /**
  * An instance of the built-in ArrayBuffer constructor (ES6 draft 15.13.5).
@@ -2336,27 +2367,40 @@ class V8EXPORT ArrayBuffer : public Object {
    * Data length in bytes.
    */
   size_t ByteLength() const;
-  /**
-   * Raw pointer to the array buffer data
-   */
-  void* Data() const;
 
   /**
    * Create a new ArrayBuffer. Allocate |byte_length| bytes.
    * Allocated memory will be owned by a created ArrayBuffer and
-   * will be deallocated when it is garbage-collected.
+   * will be deallocated when it is garbage-collected,
+   * unless the object is externalized.
    */
   static Local<ArrayBuffer> New(size_t byte_length);
 
   /**
    * Create a new ArrayBuffer over an existing memory block.
+   * The created array buffer is immediately in externalized state.
    * The memory block will not be reclaimed when a created ArrayBuffer
    * is garbage-collected.
    */
   static Local<ArrayBuffer> New(void* data, size_t byte_length);
 
+  /**
+   * Returns true if ArrayBuffer is extrenalized, that is, does not
+   * own its memory block.
+   */
+  bool IsExternal() const;
+
+  /**
+   * Pass the ownership of this ArrayBuffer's backing store to
+   * a given ArrayBufferContents.
+   */
+  void Externalize(ArrayBufferContents* contents);
+
   V8_INLINE(static ArrayBuffer* Cast(Value* obj));
 
+
+  static const int kInternalFieldCount = V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT;
+
  private:
   ArrayBuffer();
   static void CheckCast(Value* obj);