Implement SharedArrayBuffer

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index f52f8b8cfc6b8725748de27ae5896924d222aa07..b3c3e278635d0a91f056d4d72daed56b3c486032 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1920,6 +1920,13 @@ class V8_EXPORT Value : public Data {
    */
   bool IsDataView() const;
 
+  /**
+   * Returns true if this value is a SharedArrayBuffer.
+   * This is an experimental feature.
+   */
+  bool IsSharedArrayBuffer() const;
+
+
   V8_WARN_UNUSED_RESULT MaybeLocal<Boolean> ToBoolean(
       Local<Context> context) const;
   V8_WARN_UNUSED_RESULT MaybeLocal<Number> ToNumber(
@@ -3344,7 +3351,7 @@ class V8_EXPORT ArrayBuffer : public Object {
       ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);
 
   /**
-   * Returns true if ArrayBuffer is extrenalized, that is, does not
+   * Returns true if ArrayBuffer is externalized, that is, does not
    * own its memory block.
    */
   bool IsExternal() const;
@@ -3631,6 +3638,107 @@ class V8_EXPORT DataView : public ArrayBufferView {
 
 
 /**
+ * TODO(binji): document
+ * An instance of the built-in SharedArrayBuffer constructor (ES6 draft
+ * 15.13.5).
+ * This API is experimental and may change significantly.
+ */
+class V8_EXPORT SharedArrayBuffer : public Object {
+ public:
+  /**
+   * The contents of an |SharedArrayBuffer|. Externalization of
+   * |SharedArrayBuffer| returns an instance of this class, populated, with a
+   * pointer to data and byte length.
+   *
+   * The Data pointer of SharedArrayBuffer::Contents is always allocated with
+   * |ArrayBuffer::Allocator::Allocate| by the allocator specified in
+   * v8::Isolate::CreateParams::shared_array_buffer_allocator.
+   *
+   * This API is experimental and may change significantly.
+   */
+  class V8_EXPORT Contents {  // NOLINT
+   public:
+    Contents() : data_(NULL), byte_length_(0) {}
+
+    void* Data() const { return data_; }
+    size_t ByteLength() const { return byte_length_; }
+
+   private:
+    void* data_;
+    size_t byte_length_;
+
+    friend class SharedArrayBuffer;
+  };
+
+
+  /**
+   * Data length in bytes.
+   */
+  size_t ByteLength() const;
+
+  /**
+   * Create a new SharedArrayBuffer. Allocate |byte_length| bytes.
+   * Allocated memory will be owned by a created SharedArrayBuffer and
+   * will be deallocated when it is garbage-collected,
+   * unless the object is externalized.
+   */
+  static Local<SharedArrayBuffer> New(Isolate* isolate, size_t byte_length);
+
+  /**
+   * Create a new SharedArrayBuffer over an existing memory block.  The created
+   * array buffer is immediately in externalized state unless otherwise
+   * specified. The memory block will not be reclaimed when a created
+   * SharedArrayBuffer is garbage-collected.
+   */
+  static Local<SharedArrayBuffer> New(
+      Isolate* isolate, void* data, size_t byte_length,
+      ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);
+
+  /**
+   * Returns true if SharedArrayBuffer is externalized, that is, does not
+   * own its memory block.
+   */
+  bool IsExternal() const;
+
+  /**
+   * Make this SharedArrayBuffer external. The pointer to underlying memory
+   * block and byte length are returned as |Contents| structure. After
+   * SharedArrayBuffer had been etxrenalized, it does no longer owns the memory
+   * block. The caller should take steps to free memory when it is no longer
+   * needed.
+   *
+   * The memory block is guaranteed to be allocated with |Allocator::Allocate|
+   * by the allocator specified in
+   * v8::Isolate::CreateParams::shared_array_buffer_allocator.
+   *
+   */
+  Contents Externalize();
+
+  /**
+   * Get a pointer to the ArrayBuffer's underlying memory block without
+   * externalizing it. If the ArrayBuffer is not externalized, this pointer
+   * will become invalid as soon as the ArrayBuffer became garbage collected.
+   *
+   * The embedder should make sure to hold a strong reference to the
+   * ArrayBuffer while accessing this pointer.
+   *
+   * The memory block is guaranteed to be allocated with |Allocator::Allocate|
+   * by the allocator specified in
+   * v8::Isolate::CreateParams::shared_array_buffer_allocator.
+   */
+  Contents GetContents();
+
+  V8_INLINE static SharedArrayBuffer* Cast(Value* obj);
+
+  static const int kInternalFieldCount = V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT;
+
+ private:
+  SharedArrayBuffer();
+  static void CheckCast(Value* obj);
+};
+
+
+/**
  * An instance of the built-in Date constructor (ECMA-262, 15.9).
  */
 class V8_EXPORT Date : public Object {
@@ -5006,7 +5114,8 @@ class V8_EXPORT Isolate {
           counter_lookup_callback(NULL),
           create_histogram_callback(NULL),
           add_histogram_sample_callback(NULL),
-          array_buffer_allocator(NULL) {}
+          array_buffer_allocator(NULL),
+          shared_array_buffer_allocator(NULL) {}
 
     /**
      * The optional entry_hook allows the host application to provide the
@@ -5054,6 +5163,12 @@ class V8_EXPORT Isolate {
      * store of ArrayBuffers.
      */
     ArrayBuffer::Allocator* array_buffer_allocator;
+
+    /**
+     * The ArrayBuffer::Allocator to use for allocating and freeing the backing
+     * store of SharedArrayBuffers.
+     */
+    ArrayBuffer::Allocator* shared_array_buffer_allocator;

[jochen (gone - plz use gerrit), 2015/05/22 08:37:47]

why do we need a separate allocator?

[binji, 2015/05/22 09:27:34]

We probably don't. Removed.

   };
 
 
@@ -6746,7 +6861,7 @@ class Internals {
   static const int kJSObjectHeaderSize = 3 * kApiPointerSize;
   static const int kFixedArrayHeaderSize = 2 * kApiPointerSize;
   static const int kContextHeaderSize = 2 * kApiPointerSize;
-  static const int kContextEmbedderDataIndex = 78;
+  static const int kContextEmbedderDataIndex = 79;
   static const int kFullStringRepresentationMask = 0x07;
   static const int kStringEncodingMask = 0x4;
   static const int kExternalTwoByteRepresentationTag = 0x02;
@@ -7817,6 +7932,14 @@ DataView* DataView::Cast(v8::Value* value) {
 }
 
 
+SharedArrayBuffer* SharedArrayBuffer::Cast(v8::Value* value) {
+#ifdef V8_ENABLE_CHECKS
+  CheckCast(value);
+#endif
+  return static_cast<SharedArrayBuffer*>(value);
+}
+
+
 Function* Function::Cast(v8::Value* value) {
 #ifdef V8_ENABLE_CHECKS
   CheckCast(value);